date:20100502

I've been trying to write a Python C extension module that uses NumPy 
and has a subtype of numpy.ndarray written in C. However, I've run into 
a snag: calling numpy.ndarray.__new__(mysubtype, ...) triggers an 
exception in the bowels of Python (this is necessary for a handful of 
NumPy features). I'm posting to this list to try to figure out why this 
exception exists in the first place, and what (if anything) I can do to 
work around it.


The exception in question happens in Objects/typeobject.c in 
tp_new_wrapper. Here's the comment for the block:


/* Check that the use doesn't do something silly and unsafe like
   object.__new__(dict).  To do this, we check that the
   most derived base that's not a heap type is this type. */

The code has the end effect that basetype.__new__(subtype, ...) fails 
whenever subtype is a statically-defined type (i.e. a normal C extension 
type object). Why is this necessary in general? I can see why it might 
be bad for a limited number of core Python types, but it seems 
unnecessarily limiting for Python C extensions.


On a more practical note, is there a way (short of rewriting the subtype 
in Python) to work around this? It seems that I could call the type 
metaclass to create a heap type in C, but I'm not sure of all the 
implications of that.


Thanks in advance,
Jim

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Re: Help needed in downloading Brown corpus

2010-05-02 Thread Adil Kaleem

On May 2, 6:30 am, Steven D'Aprano st...@remove-this-
cybersource.com.au wrote:
 On Sat, 01 May 2010 06:28:33 -0700, Adil Kaleem wrote:
  Hi all
  I'm a masters student in NLP. I needed to download the Brown corpus. I'm
  unable to download from nltk.org with the python CLI. My network
  connection is behind a proxy server so it's creating a problem. Since I
  don't know a bit of python, so unable to figure a way out.

 This has nothing to do with Python, it is a network issue. Talk to your
 network administrator and get him to fix the proxy, or give you a way to
 bypass it. Or if you have an internet connection at home, download it
 from there.

 --
 Steven


Hi Steven,
It all had to do with configuring the network from Python IDLE,
aliter: It all had to do with Python. I could have done it, the
bypasssing. But I couldn't have learned anything if I hadn't fought
with the problem, of course it was Shashank Singh from this group who
helped me through. Bypassing is always not good, atleast for me and
therefore I came to seek the help of you all.
Thanks Steven in reading and replying to my problem.

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Re: Python dot-equals (syntax proposal)

2010-05-02 Thread Lie Ryan

On 05/02/10 10:58, Steven D'Aprano wrote:
  And Python's object system
  makes it that the argument to __getattr__ is always a string even though
  there might be a valid variable that corresponds to it:
 That is nothing to do with the object system, it is related to the 
 semantics of Python syntax. a.b doesn't mean apply the binary dot 
 operator to arguments a and b. It is syntactic sugar for look for an 
 attribute named 'b' on object a. As such, the operands that __getattr__ 
 receives are the object a and the *name* b (implemented as a string).

You just described *exactly* the reason why dot is not, and cannot be an
operator.
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Re: Python dot-equals (syntax proposal)

2010-05-02 Thread Lie Ryan

On 05/02/10 10:58, Steven D'Aprano wrote:
 On Sun, 02 May 2010 05:08:53 +1000, Lie Ryan wrote:
 
  On 05/01/10 11:16, Steven D'Aprano wrote:
  On Fri, 30 Apr 2010 12:34:34 -0400, D'Arcy J.M. Cain wrote:
  
  In practice though, I think that's a difference that makes no
  difference. It walks like an operator, it swims like an operator, and
  it quacks like an operator.
  
  
  Nope it's not. A full-time operator in python have a reflected version
  (e.g. __radd__), which dot does not have. 
 What are the reflected versions of __eq__ and __ne__ (binary == and != 
 operators)?

Python do not have them now, but it does make sense if python have
them[1]. OTOH, given current python's language semantic, __rgetattr__
doesn't make any sense; adding __rgetattr__ would require a quite
fundamental change to the language's semantic, primarily how attribute
resolution works.

[1] though they'd probably be dismissed as bad idea since equality and
inequality are supposed to be a symmetric relation; reflected
(in)equality makes it way too easy to break that premise

 And __neg__, __pos__ and __inv__ (for the unary - + and ~ operators)?
 
 And the three-argument form of __pow__ for power(1, 2, x)?

I know you're a famed nitpicker, but don't be silly, reflected operator,
by definition, only makes sense for binary operator.
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Re: pyjamas 0.7 released

2010-05-02 Thread Wolfgang Strobl

lkcl luke.leigh...@googlemail.com:

 at least _some_ input would be good!  the knowledge doesn't have to
be there: just the bugreports saying there's a problem and here's
exactly how you reproduce it would be a start!

 So please make it simpler for more people to help.

 ... how?? there's a bugtracker, wiki, svn repository, over 30
examples and a developer list.  the code really _is_ very very small
(the UI widget set, with around 75 widgets, minus the license header
text is only around 4,000 lines _total_, making it very very simple
and very very easy for people to get used to).  suggestions welcome!

Well, the bunch of programming languages and APIs I collected over the
years is large enough already. These days I prefer to stay with python
and c, spiced with an occasional domain specific language. That's why I
was attracted by pyjamas, to begin with!.  If I'd like to program using
Eclipse and Java or fool around with JavaScript, I'd do just that. But I
don't.  IMHO, that ist a general problem of translation tools - they
attract the wrong people, from the point of view a developer who looks
for people sharing some of the workload. :-)

So, Luke, I can only answer your question from the point of view of
somebody who is mostly a potentional consumer of your work, and most
problably not another developer. If you want to delegate some work you'd
like not to do yourself (for example because you prefer designing and
coding to testing and reorganizing and polishing the docs), than you
have at least to _define_ those pieces and to monitor progress. 


 Other people have
 other projects, where they invest some of their own time and money in.

 yes. been there. didn't receive any return on investment. did some
projects. received about 25% of required money to pay bills.  need
£15k pa; receiving approximately £7-8k.

   I didn't look at
  every example again, but AFAIK, this didn't change with 0.7. (Tried with
  Python 2.6.4/5 on WinXP/7 with Firefox and Chrome, if that matters).

  then please issue bugreports for as many as you feel comfortable
 with / have time for.  

Well, ok. I put my notes in a Google chart, see
http://spreadsheets.google.com/pub?key=0Au5LhqNQyrfCdGpDbTVjZFJwSERzVUFXVlg5bWl2enc

I had to write a short patch against compile.py (see issue 397) in order
to make it compile the showcase examples on Windows.

In addition, I've tried to create Selenium tests for automating the time
consuming job of checking all those examples, using Selenium IDE in
Firefox. I was my first experience using this against Ajax apps. The
results are somewhat mixed. Playing a round of lightout was a breeze,
but so far I hadn't much luck in driving the showcase example(s). I
didn't try very hard, though, because I ran out of time, as I do now.  

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Re: Python dot-equals (syntax proposal)

2010-05-02 Thread Terry Reedy


On 5/2/2010 1:05 AM, Alf P. Steinbach wrote:

On 02.05.2010 06:06, * Aahz:



and sometimes
they rebind the original target to the same object.


At the Python level that seems to be an undetectable null-operation.


If you try t=(1,2,3); t[1]+=3, if very much matters that a rebind occurs.


Granted one could see something going on in a machine code or byte code
debugger. But making that distinction (doing nothing versus
self-assignment) at the Python level seems, to me, to be meaningless.


Please do not confuse things. Augmented *assignment* must be understood 
as assignment. Failure to do so leads (and has lead) newbies into 
confusion, and puzzled posts on this list.


Terry Jan Reedy

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Re: Python dot-equals (syntax proposal)

On Sun, 02 May 2010 16:28:28 +1000, Lie Ryan wrote:

 On 05/02/10 10:58, Steven D'Aprano wrote:
  And Python's object system
  makes it that the argument to __getattr__ is always a string even
  though there might be a valid variable that corresponds to it:
 That is nothing to do with the object system, it is related to the
 semantics of Python syntax. a.b doesn't mean apply the binary dot
 operator to arguments a and b. It is syntactic sugar for look for an
 attribute named 'b' on object a. As such, the operands that
 __getattr__ receives are the object a and the *name* b (implemented as
 a string).
 
 You just described *exactly* the reason why dot is not, and cannot be an
 operator.

This would be relevant if I said it was an operator. I did not. I said it 
was a de facto operator that behaves similarly enough to operators as to 
make it reasonable to talk about dot operator. I still stand by that.

That doesn't imply that Python's implementation of a.b has to be 
identical in every last detail to Python's implementation of a+b, because 
it clearly isn't. But there are sufficient similarities to justify saying 
that it duck-types as an operator. This isn't meant to be a vigorous 
statement of fact in the same manner than CPython implements lists as 
arrays of pointers is a statement of fact. It's meant to be a hand-wavy 
dot act kinda-sorta like an operator manner.

I'm sorry if I failed to make that clear enough. I thought that 
explicitly stating that it wasn't a real operator would be sufficient.



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Re: Python dot-equals (syntax proposal)

On Sun, 02 May 2010 17:09:36 +1000, Lie Ryan wrote:

 On 05/02/10 10:58, Steven D'Aprano wrote:
 On Sun, 02 May 2010 05:08:53 +1000, Lie Ryan wrote:
 
  On 05/01/10 11:16, Steven D'Aprano wrote:
  On Fri, 30 Apr 2010 12:34:34 -0400, D'Arcy J.M. Cain wrote:
  
  In practice though, I think that's a difference that makes no
  difference. It walks like an operator, it swims like an operator,
  and it quacks like an operator.
  
  
  Nope it's not. A full-time operator in python have a reflected
  version (e.g. __radd__), which dot does not have.
 What are the reflected versions of __eq__ and __ne__ (binary == and !=
 operators)?
 
 Python do not have them now, but it does make sense if python have
 them[1]. OTOH, given current python's language semantic, __rgetattr__
 doesn't make any sense; adding __rgetattr__ would require a quite
 fundamental change to the language's semantic, primarily how attribute
 resolution works.
 
 [1] though they'd probably be dismissed as bad idea since equality and
 inequality are supposed to be a symmetric relation; reflected
 (in)equality makes it way too easy to break that premise
 
 And __neg__, __pos__ and __inv__ (for the unary - + and ~ operators)?
 
 And the three-argument form of __pow__ for power(1, 2, x)?
 
 I know you're a famed nitpicker, but don't be silly, reflected operator,
 by definition, only makes sense for binary operator.

Binary operators aren't the only kind of operator, and you claimed that:

A full-time operator in python have a reflected version.

But there are full-time operators that don't have reflected versions, so 
your claim is just *wrong*. It would still be wrong even if you had 
limited yourself to binary operators.

I have agreed with you that there are useful things people might want to 
do (e.g. function composition) that you can't do because the dot 
operator isn't a *real* operator with exactly the same semantics as 
plus operator, multiply operator and friends. I think we're in 
violent agreement, and merely disagreeing over semantics. There's no need 
to continue arguing against a position I haven't actually taken :)


-- 
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Re: sometype.new and C subclasses

On May 1, 11:03 pm, James Porter port...@alum.rit.edu wrote:
 I've been trying to write a Python C extension module that uses NumPy
 and has a subtype of numpy.ndarray written in C. However, I've run into
 a snag: calling numpy.ndarray.__new__(mysubtype, ...) triggers an
 exception in the bowels of Python (this is necessary for a handful of
 NumPy features). I'm posting to this list to try to figure out why this
 exception exists in the first place, and what (if anything) I can do to
 work around it.

 The exception in question happens in Objects/typeobject.c in
 tp_new_wrapper. Here's the comment for the block:

         /* Check that the use doesn't do something silly and unsafe like
            object.__new__(dict).  To do this, we check that the
            most derived base that's not a heap type is this type. */

 The code has the end effect that basetype.__new__(subtype, ...) fails
 whenever subtype is a statically-defined type (i.e. a normal C extension
 type object). Why is this necessary in general? I can see why it might
 be bad for a limited number of core Python types, but it seems
 unnecessarily limiting for Python C extensions.

Why don't you use mysubtype.__new__(mysubtype,...)?

If you wrote mysubtype in C, and defined a different tp_new than
ndarray, then this exception will trigger.  And it ought to; you don't
want to use ndarray's tp_new to create an object of your subclass, if
you've defined a different tp_new.


 On a more practical note, is there a way (short of rewriting the subtype
 in Python) to work around this? It seems that I could call the type
 metaclass to create a heap type in C, but I'm not sure of all the
 implications of that.

It should work if you use mysubtype.__new__(mysubtype,...).

If it doesn't do what you want, then there's probably something wrong
with the way you subclassed ndarray.


Carl Banks
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Re: PyObject_SetAttrString - doesn't set instance attribute

On May 1, 4:04 am, Jason jason.hee...@gmail.com wrote:
 I'm having a bit of trouble with C/Python bindings. Particularly,
 trying to set an instance variable from C when the object is
 initialised using PyObject_SetAttrString, but nothing seems to happen.
 The C initialisation code is:

 static void
 nautilus_python_object_instance_init (NautilusPythonObject *object)
 {

         fprintf(stderr, nautilus_python_object_instance_init called\n);

         NautilusPythonObjectClass *class;
         debug_enter();

         class = (NautilusPythonObjectClass*)(((GTypeInstance*)object)-

 g_class);

         object-instance = PyObject_CallObject(class-type, NULL);

         PyObject* test_int = PyInt_FromLong(42);

         if (object-instance == NULL)
         {
                 PyErr_Print();
         }
         else
         {
                 fprintf(stderr, Setting magic parameter\n);
                 fprintf(stderr, From C: );
                 PyObject_Print(object-instance, stderr, 0);
                 fprintf(stderr, \n);
                 int retval = PyObject_SetAttrString(object-instance,
 super_happy_magic, test_int);
                 fprintf(stderr, Result: %i\n, retval);
         }

         Py_DECREF(test_int);

 }

Not sure what you're doing here.  It looks like you are being passed
an object of a given type, then you get the type object, call it to
create another object of that type, and assign it to object-instance.


 ...and the Python module contains:

 class MenuProviderTest(nautilus.MenuProvider):

     def __init__(self):
         print From Python: %s % self

         try:
             print getattr(self, super_happy_magic)
         except AttributeError:
             print Didn't work!

 When the MenuProviderTest is created, the output is:

 nautilus_python_object_instance_init called
 Setting magic parameter
 From C: MenuProvTest.MenuProviderTest object at 0x7faee6a9fcd0
 Result: 0
 From Python: MenuProvTest.MenuProviderTest object at 0x7faee6a9fcd0
 Didn't work!

 (I've tried getattr and self.super_happy_magic, with the same effect.)

 Where am I going wrong?

You are assigning the attirbute the the object that the C code refers
to as object-instance, but it seems that in the Python snippet you
are calling getattr on the object that the C code refers to as
object.


Carl Banks
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help error : Failed to build these modules: _dbm

2010-05-02 Thread michel parker


Hi,
When i make python 3.1 on my ubuntu 9.10 i get following error :

Failed to build these modules:
_dbm 
Please help me.
I have done :
apt-get build-dep python2.5

but to no avail.
Cheers

  
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Re: Python dot-equals (syntax proposal)

On Sun, 02 May 2010 04:04:11 -0400, Terry Reedy wrote:

 On 5/2/2010 1:05 AM, Alf P. Steinbach wrote:
 On 02.05.2010 06:06, * Aahz:
 
 and sometimes
 they rebind the original target to the same object.

 At the Python level that seems to be an undetectable null-operation.
 
 If you try t=(1,2,3); t[1]+=3, if very much matters that a rebind
 occurs.
 
 Granted one could see something going on in a machine code or byte code
 debugger. But making that distinction (doing nothing versus
 self-assignment) at the Python level seems, to me, to be meaningless.
 
 Please do not confuse things. Augmented *assignment* must be understood
 as assignment. Failure to do so leads (and has lead) newbies into
 confusion, and puzzled posts on this list.

I think that if you think *only* about Python's standard namespaces, self-
assignment is more or less a no-op. I can't think of any way that x = x 
could do anything other than use CPU cycles, *if* you limit yourself to 
the standard global or function local namespaces.

But if you think about custom namespace types, and item assignment (e.g. 
the example you gave with a tuple), the situation becomes different. 
Here's a nice example, using Python 3.1:

 class B(A):  # class A defined elsewhere -- see below.
... x = 1
... x = x
...
Traceback (most recent call last):
  File stdin, line 1, in module
  File stdin, line 3, in B
  File stdin, line 4, in __setitem__
TypeError: can't rebind constants

Thus proving that self-assignment is not necessarily a no-op. How did I 
make that work? It takes a custom dict and a bit of metaclass magic:


class ConstantNamespace(dict):
def __setitem__(self, key, value):
if key in self:
raise TypeError(can't rebind constants)
super(ConstantNamespace, self).__setitem__(key, value)

class WriteOnceClass(type):
@classmethod
def __prepare__(metacls, name, bases):
return ConstantNamespace()
def __new__(cls, name, bases, classdict):
return type.__new__(cls, name, bases, classdict)

class A(metaclass=WriteOnceClass):
pass



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Re: PyObject_SetAttrString - doesn't set instance attribute

2010-05-02 Thread Jason

On May 2, 5:52 pm, Carl Banks pavlovevide...@gmail.com wrote:
 Not sure what you're doing here.  It looks like you are being passed
 an object of a given type, then you get the type object, call it to
 create another object of that type, and assign it to object-instance.

Sorry, I should have noted that the NautilusPythonObject type in the
code is a struct defined as:

struct _NautilusPythonObject {
  GObject parent_slot;
  PyObject *instance;
};

 You are assigning the attirbute the the object that the C code refers
 to as object-instance, but it seems that in the Python snippet you
 are calling getattr on the object that the C code refers to as
 object.

object-instance is the PyObject, and I gathered that it was the
correct thing to assign to from the fact that the address is identical
as seen from C and Python.

— Jason
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Re: help error : Failed to build these modules: _dbm

2010-05-02 Thread Kushal Kumaran

On Sun, May 2, 2010 at 3:30 PM, michel parker michelpar...@live.com wrote:
 Hi,
 When i make python 3.1 on my ubuntu 9.10 i get following error :

 Failed to build these modules:
 _dbm
 Please help me.
 I have done :

 apt-get build-dep python2.5

 but to no avail.
 Cheers



Probably the packages libdb4.7-dev (if you want berkeley db) or
libgdbm-dev (if you want gnu dbm).

ISTR there was a thread about this just a couple of days ago.

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Re: Python dot-equals (syntax proposal)

2010-05-02 Thread Albert van der Horst

In article mailman.2429.1272646255.23598.python-l...@python.org,
Jean-Michel Pichavant  jeanmic...@sequans.com wrote:
Jabapyth wrote:
 At least a few times a day I wish python had the following shortcut
 syntax:

 vbl.=func(args)

 this would be equivalent to

 vbl = vbl.func(args)

 example:

 foo = Hello world
 foo.=split( )
 print foo
 # ['Hello', 'world']

 and I guess you could generalize this to

 vbl.=[some text]
 #
 vbl = vbl.[some text]

 e.g.

 temp.=children[0]
 # temp = temp.children[0]

 thoughts?

Useless if you use meaningful names for your variables  attributes.

It may happen that one object attribute refer to an object of the same
type, but it is quite rare that both can share the same name anyway.

Possible use cases:

1/
car = Car()
car = car.wheel # ???

2/
wheel = Car() # ???
wheel = wheel.wheel # ???

3/
currentCar = Car()
currentCar = currentCar.nextCar

The syntax you prose will be applicable on very little assignements (use
case 3). I'm not sure it's worth it.

Note how related it is to the requirement to have a _radd_ operator.

It amounts to the argument that
a op= b
requires that a and b have somewhat similar type, or that
the type of a doesn't really change as a result from the operation.

This is IMHO an argument against the .= pseudo-operator.


JM

Groetjes Albert

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Re: matching strings in a large set of strings

2010-05-02 Thread Albert van der Horst

In article 877hnpjtdw@rudin.co.uk,
Paul Rudin  paul.nos...@rudin.co.uk wrote:
Karin Lagesen karin.lage...@bio.uio.no writes:

 Hello.

 I have approx 83 million strings, all 14 characters long. I need to be
 able to take another string and find out whether this one is present
 within the 83 million strings.

 Now, I have tried storing these strings as a list, a set and a dictionary.
 I know that finding things in a set and a dictionary is very much faster
 than working with a list, so I tried those first. However, I run out of
 memory building both the set and the dictionary, so what I seem to be left
 with is the list, and using the in method.

 I imagine that there should be a faster/better way than this?


Shouldn't a set with 83 million 14 character strings be fine in memory
on a stock PC these days? I suppose if it's low on ram you might start
swapping which will kill performance. Perhaps the method you're using to
build the data structures creates lots of garbage? How much ram do you
have and how much memory does the python process use as it builds your
data structures?

And if this is practical there should be no swapping problems,
as the working set will be a small fraction of the data used.

SNIP

There are other algorithms you can use that have better theoretical
performance than using bisect for this particular problem, but you get
into trade offs between executing things in python as opposed to C if
you start to hand code things in python.

There are a lot of possibility, but they depend a great deal on
secondary conditions, like how often the 83 M dataset changes.

Groetjes Albert

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Economic growth -- being exponential -- ultimately falters.
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RE: help error : Failed to build these modules: _dbm

2010-05-02 Thread michel parker

hi,
yup problem solved module was missing  libgdbm-dev
 From: kushal.kumaran+pyt...@gmail.com
 Date: Sun, 2 May 2010 16:38:28 +0530
 Subject: Re: help error : Failed to build these modules: _dbm
 To: michelpar...@live.com
 CC: python-list@python.org

 On Sun, May 2, 2010 at 3:30 PM, michel parker michelpar...@live.com wrote:
  Hi,
  When i make python 3.1 on my ubuntu 9.10 i get following error :

  Failed to build these modules:
  _dbm
  Please help me.
  I have done :

  apt-get build-dep python2.5

  but to no avail.
  Cheers

 Probably the packages libdb4.7-dev (if you want berkeley db) or
 libgdbm-dev (if you want gnu dbm).

 ISTR there was a thread about this just a couple of days ago.

 -- 
 regards,
 kushal

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help req setting python executable

2010-05-02 Thread michel parker


hi,
i have just installed python3.1 with opt=g option.
but when i set python executable in wingide to usr/local/bin/python3.1 it says :
Some values are invalid:

- Python executable 'usr/local/bin/python3.1' is not in path

Please correct the values and try again.

Please help. What is going to be correct pythonpath for me.
i have installed python using standard sudo make install method.
Cheers
  
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Bug in Python set

2010-05-02 Thread dmitrey

Python 2.6.5 r265:79063
set().update(set()) is None
True
while I expect result of update to be set.
Also, result of
set().add(None)
is None while I expect it to be set with element None (or, maybe, it
should be empty set?)

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Re: recommended way to insert data into a one to many relationship using python

Peter Otten wrote:

If you create indices for floors (and rooms)

cur.execute(create unique index room_index on rooms (fid, number);)
cur.execute(create unique index floor_index on floors (floor);)

the addition of missing rows can be simplified to

missing = c2.execute(select distinct floor from new_employees;)
cur.executemany(insert or ignore into floors (floor) values (?), missing)

etc.

Peter
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Re: Bug in Python set

2010-05-02 Thread Aahz

In article 0bd314a8-db65-43f1-a999-521e2ed71...@n15g2000yqf.googlegroups.com,
dmitrey  dmitrey.kros...@scipy.org wrote:

Python 2.6.5 r265:79063
set().update(set()) is None
True
while I expect result of update to be set.
Also, result of
set().add(None)
is None while I expect it to be set with element None (or, maybe, it
should be empty set?)

Why are you assuming that your expectations are correct?  Generally
speaking, Python methods that mutate do *not* return the original object,
precisely to make sure you don't make stupid mistakes.

You should probably read this:

http://www.catb.org/~esr/faqs/smart-questions.html
-- 
Aahz (a...@pythoncraft.com)   * http://www.pythoncraft.com/

It is easier to optimize correct code than to correct optimized code.
--Bill Harlan
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Re: Bug in Python set

On Sun, 02 May 2010 05:11:40 -0700, dmitrey wrote:

 Python 2.6.5 r265:79063
set().update(set()) is None
 True
 while I expect result of update to be set.

Change your expectations. Generally, methods which modify the object 
rather than creating a new one return None.

 s = set([1,2,3])
 s.update(set([3, 4, 5]))
 s
{1, 2, 3, 4, 5}


 Also, result of set().add(None) is None while I expect it to be set
 with element None (or, maybe, it should be empty set?)

 s = set()
 s.add(None)
 s
{None}


Python sets have been used by tens of thousands of programmers for many 
years now. Which do you think is more likely?

(1) Not one person before you noticed that something as fundamental as 
adding an item to a set is buggy;

or

(2) You have misunderstood what is happening?



-- 
Steven
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List size versus list allocation

Python lists are over-allocated: whenever they need to be resized, they 
are made a little bit larger than necessary so that appends will be fast.

See:

http://code.python.org/hg/trunk/file/e9d930f8b8ff/Objects/listobject.c

I'm interested in gathering some statistics on this, and to do so I need 
a way of measuring the list's logical size versus its actual size. The 
first is easy: it's just len(list). Is there some way of getting the 
allocated size of the list?



-- 
Steven
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Re: Fast Efficient way to transfer an object to another list

2010-05-02 Thread Hans Mulder


Francesco Bochicchio wrote:


Anyway i think that list.extract( old_list, predicate ) - new_list
would be a nice addition to the standard library


You could use filter( predicate, old_list ) - new_list

-- HansM



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Re: help req setting python executable

2010-05-02 Thread D'Arcy J.M. Cain

On Sun, 2 May 2010 12:59:35 +0100
michel parker michelpar...@live.com wrote:
 
 hi,
 i have just installed python3.1 with opt=g option.
 but when i set python executable in wingide to usr/local/bin/python3.1 it 
 says :

I don't know anything about wingide but I think your problem is simply
a missing slash.

/usr/local/bin/python3.1

-- 
D'Arcy J.M. Cain da...@druid.net |  Democracy is three wolves
http://www.druid.net/darcy/|  and a sheep voting on
+1 416 425 1212 (DoD#0082)(eNTP)   |  what's for dinner.
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Re: List size versus list allocation

Steven D'Aprano wrote:

 Python lists are over-allocated: whenever they need to be resized, they
 are made a little bit larger than necessary so that appends will be fast.
 
 See:
 
 http://code.python.org/hg/trunk/file/e9d930f8b8ff/Objects/listobject.c
 
 I'm interested in gathering some statistics on this, and to do so I need
 a way of measuring the list's logical size versus its actual size. The
 first is easy: it's just len(list). Is there some way of getting the
 allocated size of the list?

With some brute force guesswork...

 a = [None] * 42
 for i in range(10):
... print i, ctypes.c_ulong.from_address(id(a)+i*8)
...
0 c_ulong(1L)
1 c_ulong(8488896L)
2 c_ulong(42L)
3 c_ulong(37432768L)
4 c_ulong(42L)
5 c_ulong(1L)
6 c_ulong(8510496L)
7 c_ulong(32L)
8 c_ulong(18446744073709551615L)
9 c_ulong(8935143189711421440L)
 a = []
 for i in range(42): a.append(None)
...
 for i in range(10):
... print i, ctypes.c_ulong.from_address(id(a)+i*8)
...
0 c_ulong(1L)
1 c_ulong(8488896L)
2 c_ulong(42L)
3 c_ulong(40136160L)
4 c_ulong(46L)
5 c_ulong(0L)
6 c_ulong(0L)
7 c_ulong(0L)
8 c_ulong(0L)
9 c_ulong(0L)

... you can see that the size sits at offset 4*sizeof(long) on my 64-bit 
Python. With that information we can take a look at a list's overallocation 
strategy:

 a = []
 for i in range(20):
... print i, ctypes.c_ulong.from_address(id(a)+4*8)
... a.append(None)
...
0 c_ulong(0L)
1 c_ulong(4L)
2 c_ulong(4L)
3 c_ulong(4L)
4 c_ulong(4L)
5 c_ulong(8L)
6 c_ulong(8L)
7 c_ulong(8L)
8 c_ulong(8L)
9 c_ulong(16L)
10 c_ulong(16L)
11 c_ulong(16L)
12 c_ulong(16L)
13 c_ulong(16L)
14 c_ulong(16L)
15 c_ulong(16L)
16 c_ulong(16L)
17 c_ulong(25L)
18 c_ulong(25L)
19 c_ulong(25L)

Peter
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Re: List size versus list allocation

2010-05-02 Thread Christian Heimes


I'm interested in gathering some statistics on this, and to do so I need
a way of measuring the list's logical size versus its actual size. The
first is easy: it's just len(list). Is there some way of getting the
allocated size of the list?


With Python 2.6 and newer you can use sys.getsizeof() to get the actual 
size of the list object:



import sys, struct
sys.getsizeof([])

72

a = [1,2,3]
b = []
b.append(1)
b.append(2)
b.append(3)
sys.getsizeof(a)

96

sys.getsizeof(b)

104

def slots(lst):
... return (sys.getsizeof(lst) - sys.getsizeof([])) / 
struct.calcsize(P)

...

slots(b)

4

slots(a)

3

Christian

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Re: List size versus list allocation

Christian Heimes wrote:

 def slots(lst):
 ... return (sys.getsizeof(lst) - sys.getsizeof([])) /

D'oh!

Peter
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condition and True or False

2010-05-02 Thread Paul McGuire

While sifting through some code looking for old x and y or z code
that might better be coded using y if x else z, I came across this
puzzler:

x = boolean expression and True or False

What is and True or False adding to this picture?  The boolean
expression part is already evaluating to a boolean, so I don't
understand why a code author would feel compelled to beat this one
over the head with the additional and True or False.

I did a little code Googling and found a few other Python instances of
this, but also many Lua instances.  I'm not that familiar with Lua, is
this a practice that one who uses Lua frequently might carry over to
Python, not realizing that the added and True or False is redundant?

Other theories?

-- Paul
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Re: sometype.new and C subclasses


On 5/2/2010 4:34 AM, Carl Banks wrote:

Why don't you use mysubtype.__new__(mysubtype,...)?

If you wrote mysubtype in C, and defined a different tp_new than
ndarray, then this exception will trigger.  And it ought to; you don't
want to use ndarray's tp_new to create an object of your subclass, if
you've defined a different tp_new.


Unfortunately, I can't do that, since that call is in NumPy itself and 
it's part of their standard way of making instances of subclasses of 
ndarray. Functions like numpy.zeros_like use ndarray.__new__(subtype, 
...) to create new arrays based on the shape of other arrays.


The Python version of the subclass is shown here: 
http://docs.scipy.org/doc/numpy/user/basics.subclassing.html#slightly-more-realistic-example-attribute-added-to-existing-array, 
and I'm trying to write something pretty similar in C. I'm trying to 
stay in C since everything else is in C, so it's easier to stay in C 
then to jump back and forth all the time.


Maybe the real answer to this question is NumPy is doing it wrong and 
I should be on their list; still, it seems strange that the behavior is 
different between Python and C.


- Jim

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Python debuggers with sys.settrace()

2010-05-02 Thread Sarah Mount

This is a bit of an odd question, but is there any way for a Python
debugger to suppress I/O generated by the program which is being
debugged? I guess an obvious thing to do would be to replace core
parts of the standard library and change any relevant imports in the
locals and globals dicts to fake ones which don't generate I/O, but
this seems brittle as the standard library will change over time. Is
it possible to modify the byte-compiled code in each stack frame? Or
is there a simpler way to do this?

Many thanks,

Sarah

-- 
Sarah Mount, Senior Lecturer, University of Wolverhampton
website:  http://www.snim2.org/
twitter: @snim2
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Re: condition and True or False

Paul McGuire wrote:

 While sifting through some code looking for old x and y or z code
 that might better be coded using y if x else z, I came across this
 puzzler:
 
 x = boolean expression and True or False
 
 What is and True or False adding to this picture?  The boolean
 expression part is already evaluating to a boolean, so I don't
 understand why a code author would feel compelled to beat this one
 over the head with the additional and True or False.
 
 I did a little code Googling and found a few other Python instances of
 this, but also many Lua instances.  I'm not that familiar with Lua, is
 this a practice that one who uses Lua frequently might carry over to
 Python, not realizing that the added and True or False is redundant?
 
 Other theories?

If it were e. g.

def f():
big_beast = list(range(10**100))
return big_beast and True or False
x = f()

it would prevent that a big_beast reference becomes visible outside the 
function and allow for immediate release of its memory.

Peter
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Re: assigning multi-line strings to variables

2010-05-02 Thread Sibylle Koczian


goldtech schrieb:

Thank you to posters for help to my question. Seems I had trouble with
triple quotes strings in the PythonWin shell. But using the Idle shell
things work as expected. But this is probably another issue...any way,
w/Idle's shell I got the action regarding multiline strings I
expected.


What PythonWin version? I remember having had such trouble years ago, 
probably Python 1.something.


Greetings
Sibylle
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Re: condition and True or False

2010-05-02 Thread Vito 'ZeD' De Tullio

Peter Otten wrote:

 def f():
 big_beast = list(range(10**100))
 return big_beast and True or False
 x = f()
 
 it would prevent that a big_beast reference becomes visible outside the
 function and allow for immediate release of its memory.

what's wrong in bool(big_beast)?

-- 
By ZeD

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Re: sometype.new and C subclasses

2010-05-02 Thread Robert Kern

On 2010-05-02 12:48 , James Porter wrote:

On 5/2/2010 4:34 AM, Carl Banks wrote:

Why don't you use mysubtype.__new__(mysubtype,...)?

If you wrote mysubtype in C, and defined a different tp_new than
ndarray, then this exception will trigger. And it ought to; you don't
want to use ndarray's tp_new to create an object of your subclass, if
you've defined a different tp_new.

Unfortunately, I can't do that, since that call is in NumPy itself and
it's part of their standard way of making instances of subclasses of
ndarray. Functions like numpy.zeros_like use ndarray.__new__(subtype,
...) to create new arrays based on the shape of other arrays.

The Python version of the subclass is shown here:
http://docs.scipy.org/doc/numpy/user/basics.subclassing.html#slightly-more-realistic-example-attribute-added-to-existing-array,
and I'm trying to write something pretty similar in C. I'm trying to
stay in C since everything else is in C, so it's easier to stay in C
then to jump back and forth all the time.

Maybe the real answer to this question is NumPy is doing it wrong and
I should be on their list; still, it seems strange that the behavior is
different between Python and C.

Perhaps things would be clearer if you could post the C code that you've written
that fails. So far, you've only alluded at what you are doing using
Python-syntax examples.

--
Robert Kern

I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth.
-- Umberto Eco

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Re: recommended way to insert data into a one to many relationship using python

2010-05-02 Thread Bryan

Wolfgang Meiners wrote:
 one to many relationships are fairly common, i think. So there should be
 a recommended way to insert data into such a relation using python.

 Given the following programm, what is the recommended way to insert the
 list of NewEmployees to the database?

 
 # !python
 # -*- coding: utf-8 -*-

 import sqlite3

 con = sqlite3.connect(:memory:)
 cur = con.cursor()

 cur.execute(create table employees(
     eid integer primary key autoincrement,
     name text not null,
     rid integer references rooms(rid)))

 cur.execute(create table rooms(
     rid integer primary key autoincrement,
     number integer,
     fid integer references floors(fid)))

 cur.execute(create table floors(
     fid integer primary key autoincrement,
     floor text not null))

[...]

 NewEmployees  =[]
 NewEmployees.append({'name': 'George', 'room': 89, 'floor': 'third floor'})
 NewEmployees.append({'name': 'Ellen', 'room': 21, 'floor': 'first floor'})


For that kind of insert to be well-defined, the pair (floor,
room_number) must uniquely identify a room. When natural keys like
that are availabe, they're the obvious choice for primary keys in the
database schema. I suggested getting rid of fid and rid, as in:


schema = 
CREATE TABLE floors (
floor TEXT PRIMARY KEY
);

CREATE TABLE rooms (
floor TEXT REFERENCES floors,
number INTEGER,
PRIMARY KEY (floor, number)
);

CREATE TABLE employees (
eid INTEGER PRIMARY KEY AUTOINCREMENT,
name TEXT,
floor TEXT,
room_number INTEGER,
FOREIGN KEY (floor, room_number) REFERENCES rooms
)


con = sqlite3.connect(:memory:)
for cmd in schema.split(';'):
con.execute(cmd)
con.close()



--
--Bryan
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Re: Bug in Python set

2010-05-02 Thread Terry Reedy


On 5/2/2010 8:11 AM, dmitrey wrote:

Python 2.6.5 r265:79063

set().update(set()) is None

True
while I expect result of update to be set.
Also, result of
set().add(None)
is None while I expect it to be set with element None (or, maybe, it
should be empty set?)


'Expect' has two different meanings in this context.
1. The empirical behavior surprised me (because I did not bother to read 
the manual, which clearly says what the returns are).
2. The documented behavior, which I read, surprises me, because I would 
have designed things differently, perhaps because I have used other 
languages designed differently.


I am not sure which you meant.



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Parser

2010-05-02 Thread Andreas Löscher

Hi,
I am looking for an easy to use parser. I am want to get an overview
over parsing and want to try to get some information out of a C-Header
file. Which parser would you recommend?

Best,
Andreas

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Re: sometype.new and C subclasses


On 5/2/2010 1:43 PM, Robert Kern wrote:

Perhaps things would be clearer if you could post the C code that you've
written that fails. So far, you've only alluded at what you are doing
using Python-syntax examples.


I'm not sure how much this will help, but here you go. The actual C code 
probably doesn't matter except for where I set tp_flags, tp_new, and 
register the type, but I included it for completeness. The full C source 
is available here if you need it, but be warned that other strangeness 
abounds in the code: 
http://trac.mcs.anl.gov/projects/ITAPS/browser/python/trunk/iMesh_array.inl?rev=3831.


Obviously, this is kind of a bizarre case, so I'm not entirely sure what 
the best route is here.


Thanks,
Jim

static PyObject*
iMeshArrObj_new(PyTypeObject *cls,PyObject *args,PyObject *kw)
{
static char *kwlist[] = {object,instance,0};

PyObject *obj;
iMesh_Object *instance = NULL;
PyObject *arr = NULL;
iMeshArr_Object *self;

if(!PyArg_ParseTupleAndKeywords(args,kw,O|O!,kwlist,obj,
iMesh_Type,instance))
return NULL;

arr = PyArray_FROM_O(obj);
if(arr == NULL)
return NULL;

self = (iMeshArr_Object*)PyObject_CallMethod(arr,view,O,cls);
Py_DECREF(arr);
if(self == NULL)
return NULL;

/* some boring stuff to set |instance| */

return self;
}

static void
iMeshArrObj_dealloc(iMeshArr_Object *self)
{
Py_XDECREF(self-instance);
self-array.ob_type-tp_free((PyObject*)self);
}

static PyObject*
iMeshArrObj_finalize(iMeshArr_Object *self,PyObject *args)
{
iMeshArr_Object *context;
if(PyArg_ParseTuple(args,O!,iMeshArr_Type,context))
{
self-instance = context-instance;
Py_XINCREF(self-instance);
}
PyErr_Clear();
Py_RETURN_NONE;
}

static PyMethodDef iMeshArrObj_methods[] = {
{ __array_finalize__, (PyCFunction)iMeshArrObj_finalize,
  METH_VARARGS, 
},
{0}
};

static PyMemberDef iMeshArrObj_members[] = {
{instance, T_OBJECT_EX, offsetof(iMeshArr_Object, instance),
 READONLY, base iMesh instance},
{0}
};

static PyTypeObject iMeshArr_Type = {
PyObject_HEAD_INIT(NULL)
/* ... */
(destructor)iMeshArrObj_dealloc,  /* tp_dealloc */
/* ... */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
iMesh array objects,/* tp_doc */
/* ... */
iMeshArrObj_methods,  /* tp_methods */
iMeshArrObj_members,  /* tp_members */
/* ... */
iMeshArrObj_new,  /* tp_new */
};

PyMODINITFUNC initiMesh(void)
{
PyObject *m;
m = Py_InitModule(iMesh,module_methods);
import_array();

iMeshArr_Type.tp_base = PyArray_Type;  
if(PyType_Ready(iMeshArr_Type)  0)
return;
Py_INCREF(iMeshArr_Type);
PyModule_AddObject(m,Array,(PyObject *)iMeshArr_Type);
}

/* End C code */

And then in Python:

A = iMesh.Array(numpy.array([1,2,3,4,5]), instance=mesh)
numpy.zeros_like(A) # fails here

Inside NumPy, zeros_like looks like this (there's a bit more than this, 
but it's irrelevant to this problem):


def zeros_like(a):
if isinstance(a, ndarray):
res = ndarray.__new__(type(a), a.shape, a.dtype,
  order=a.flags.fnc)
res.fill(0)
return res

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Re: condition and True or False

2010-05-02 Thread David Robinow

On Sun, May 2, 2010 at 1:14 PM, Paul McGuire pt...@austin.rr.com wrote:
 While sifting through some code looking for old x and y or z code
 that might better be coded using y if x else z, I came across this
 puzzler:

    x = boolean expression and True or False

 What is and True or False adding to this picture?  The boolean
 expression part is already evaluating to a boolean, so I don't
 understand why a code author would feel compelled to beat this one
 over the head with the additional and True or False.

 I did a little code Googling and found a few other Python instances of
 this, but also many Lua instances.  I'm not that familiar with Lua, is
 this a practice that one who uses Lua frequently might carry over to
 Python, not realizing that the added and True or False is redundant?

 Other theories?

 -- Paul
 --
 http://mail.python.org/mailman/listinfo/python-list

True and False were added in Python 2.2.1  (PEP 285)
Perhaps this was a silly way to ensure that the user wouldn't try to
run it in earlier versions.
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Re: Parser

2010-05-02 Thread Jason Scheirer

On May 2, 12:54 pm, Andreas Löscher andreas.loesc...@s2005.tu-
chemnitz.de wrote:
 Hi,
 I am looking for an easy to use parser. I am want to get an overview
 over parsing and want to try to get some information out of a C-Header
 file. Which parser would you recommend?

 Best,
 Andreas

Pyparsing: http://pyparsing.wikispaces.com/
I've abused the lexers built in to Pygments ( http://pygments.org/ ) a
few times to decent effect too.
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Re: sometype.new and C subclasses

On May 2, 10:48 am, James Porter port...@alum.rit.edu wrote:
 On 5/2/2010 4:34 AM, Carl Banks wrote:

  Why don't you use mysubtype.__new__(mysubtype,...)?

  If you wrote mysubtype in C, and defined a different tp_new than
  ndarray, then this exception will trigger.  And it ought to; you don't
  want to use ndarray's tp_new to create an object of your subclass, if
  you've defined a different tp_new.

 Unfortunately, I can't do that, since that call is in NumPy itself and
 it's part of their standard way of making instances of subclasses of
 ndarray. Functions like numpy.zeros_like use ndarray.__new__(subtype,
 ...) to create new arrays based on the shape of other arrays.

 The Python version of the subclass is shown here:
 http://docs.scipy.org/doc/numpy/user/basics.subclassing.html#slightly...,
 and I'm trying to write something pretty similar in C. I'm trying to
 stay in C since everything else is in C, so it's easier to stay in C
 then to jump back and forth all the time.

 Maybe the real answer to this question is NumPy is doing it wrong and
 I should be on their list; still, it seems strange that the behavior is
 different between Python and C.

I would say numpy is wrong here, so I suggest filing a bug report.

In fact I can't think of any benefit to EVER calling X.__new__(Y)
where X is not Y.  Maybe old-style classes?  Someone who wants to
ensure they're getting an instance of a certain type can check
issubclass(Y,X) then call Y.__new__(Y).

Unfortunately, you just can't get rid of the test in tp_new_wrapper.


Carl Banks
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Re: sometype.new and C subclasses

2010-05-02 Thread Robert Kern


On 2010-05-02 15:28 , Carl Banks wrote:

On May 2, 10:48 am, James Porterport...@alum.rit.edu  wrote:

On 5/2/2010 4:34 AM, Carl Banks wrote:


Why don't you use mysubtype.__new__(mysubtype,...)?



If you wrote mysubtype in C, and defined a different tp_new than
ndarray, then this exception will trigger.  And it ought to; you don't
want to use ndarray's tp_new to create an object of your subclass, if
you've defined a different tp_new.


Unfortunately, I can't do that, since that call is in NumPy itself and
it's part of their standard way of making instances of subclasses of
ndarray. Functions like numpy.zeros_like use ndarray.__new__(subtype,
...) to create new arrays based on the shape of other arrays.

The Python version of the subclass is shown here:
http://docs.scipy.org/doc/numpy/user/basics.subclassing.html#slightly...,
and I'm trying to write something pretty similar in C. I'm trying to
stay in C since everything else is in C, so it's easier to stay in C
then to jump back and forth all the time.

Maybe the real answer to this question is NumPy is doing it wrong and
I should be on their list; still, it seems strange that the behavior is
different between Python and C.


I would say numpy is wrong here, so I suggest filing a bug report.

In fact I can't think of any benefit to EVER calling X.__new__(Y)
where X is not Y.  Maybe old-style classes?  Someone who wants to
ensure they're getting an instance of a certain type can check
issubclass(Y,X) then call Y.__new__(Y).


Well, the Y.__new__(Y) may call X.__new__(Y) (and we certainly do this 
successfully in other Python subclasses of ndarray; this also appears in the 
Python regression tests). I'm not sure why this would be permitted there and not 
in a regular function (numpy.zeros_like() seems to be the function that does 
this and fails for the OP). The reason we do it there instead of calling the 
subclass's constructor is because the subclass's constructor may have different 
arguments.


I'm happy to concede that this might be a bug in numpy, but I don't understand 
why this is allowed for Python subclasses but not C subtypes.


--
Robert Kern

I have come to believe that the whole world is an enigma, a harmless enigma
 that is made terrible by our own mad attempt to interpret it as though it had
 an underlying truth.
  -- Umberto Eco

--
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Re: sometype.new and C subclasses

2010-05-02 Thread Robert Kern


On 2010-05-02 15:03 , James Porter wrote:


And then in Python:

A = iMesh.Array(numpy.array([1,2,3,4,5]), instance=mesh)
numpy.zeros_like(A) # fails here

Inside NumPy, zeros_like looks like this (there's a bit more than this,
but it's irrelevant to this problem):

def zeros_like(a):
if isinstance(a, ndarray):
res = ndarray.__new__(type(a), a.shape, a.dtype,
order=a.flags.fnc)
res.fill(0)
return res


Well, I think we can change zeros_like() and the rest to work around this issue. 
Can you bring it up on the numpy mailing list?


def zeros_like(a):
if isinstance(a, ndarray):
res = numpy.empty(a.shape, a.dtype, order=a.flags.fnc)
res.fill(0)
res = res.view(type(a))
return res
...

--
Robert Kern

I have come to believe that the whole world is an enigma, a harmless enigma
 that is made terrible by our own mad attempt to interpret it as though it had
 an underlying truth.
  -- Umberto Eco

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Re: PyObject_SetAttrString - doesn't set instance attribute

On May 2, 3:26 am, Jason jason.hee...@gmail.com wrote:
 On May 2, 5:52 pm, Carl Banks pavlovevide...@gmail.com wrote:

  Not sure what you're doing here.  It looks like you are being passed
  an object of a given type, then you get the type object, call it to
  create another object of that type, and assign it to object-instance.

 Sorry, I should have noted that the NautilusPythonObject type in the
 code is a struct defined as:

 struct _NautilusPythonObject {
   GObject parent_slot;
   PyObject *instance;

 };
  You are assigning the attirbute the the object that the C code refers
  to as object-instance, but it seems that in the Python snippet you
  are calling getattr on the object that the C code refers to as
  object.

 object-instance is the PyObject, and I gathered that it was the
 correct thing to assign to from the fact that the address is identical
 as seen from C and Python.

We'd have to see more code, I'd think.  What you posted needs more
context.  For instance, what type, exactly, is class-type?  This
would help us understand better.

I don't understand how object-instance and self could be the same
object.  If they have the same address it's possible (and, I'm
inclined to think, likely) that you're creating an object, it's
getting destroyed, then you are creating another one.

Here's what's really odd.  You are calling getattr(self,
super_happy_magic) inside __init__, which is the class's
initializer.  How could you have had occasion to call
PyObject_SetAttrString on that same object at that point?  The only
possible way it could have happened is if
nautilus_python_object_instance_init is invoked by
MenuProviderTest.__new__ somehow, but that doesn't make sense either.
You run PyObject_CallObject(class-type,NULL) to create object-
instance, but calling a type also calls the type's __init__ method.
So how is it that later the __init__ method is being called again on
the same object?  Unless you're doing something very weird, it could
only mean it's a different object.

I doubt it'll fix all your problems, but one thing to try is to
replace PyObject_CallObject(class-type, NULL); with class-type-
tp_new(class-type);.

But you probably have to go back to the drawing board and rethink the
whole thing.  What you've posted is quite unusual.


You should choose more descriptive variable names, too.


Carl Banks
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Re: sometype.new and C subclasses

On May 2, 1:51 pm, Robert Kern robert.k...@gmail.com wrote:
 On 2010-05-02 15:28 , Carl Banks wrote:



  On May 2, 10:48 am, James Porterport...@alum.rit.edu  wrote:
  On 5/2/2010 4:34 AM, Carl Banks wrote:

  Why don't you use mysubtype.__new__(mysubtype,...)?

  If you wrote mysubtype in C, and defined a different tp_new than
  ndarray, then this exception will trigger.  And it ought to; you don't
  want to use ndarray's tp_new to create an object of your subclass, if
  you've defined a different tp_new.

  Unfortunately, I can't do that, since that call is in NumPy itself and
  it's part of their standard way of making instances of subclasses of
  ndarray. Functions like numpy.zeros_like use ndarray.__new__(subtype,
  ...) to create new arrays based on the shape of other arrays.

  The Python version of the subclass is shown here:
  http://docs.scipy.org/doc/numpy/user/basics.subclassing.html#slightly...,
  and I'm trying to write something pretty similar in C. I'm trying to
  stay in C since everything else is in C, so it's easier to stay in C
  then to jump back and forth all the time.

  Maybe the real answer to this question is NumPy is doing it wrong and
  I should be on their list; still, it seems strange that the behavior is
  different between Python and C.

  I would say numpy is wrong here, so I suggest filing a bug report.

  In fact I can't think of any benefit to EVER calling X.__new__(Y)
  where X is not Y.  Maybe old-style classes?  Someone who wants to
  ensure they're getting an instance of a certain type can check
  issubclass(Y,X) then call Y.__new__(Y).

 Well, the Y.__new__(Y) may call X.__new__(Y) (and we certainly do this
 successfully in other Python subclasses of ndarray; this also appears in the
 Python regression tests). I'm not sure why this would be permitted there and 
 not
 in a regular function (numpy.zeros_like() seems to be the function that does
 this and fails for the OP). The reason we do it there instead of calling the
 subclass's constructor is because the subclass's constructor may have 
 different
 arguments.

 I'm happy to concede that this might be a bug in numpy, but I don't understand
 why this is allowed for Python subclasses but not C subtypes.

Because Python subclasses (i.e., heap types) all invoke
tp_new_wrapper, which is guaranteed to call the tp_new of the most
derived base.

C subtypes can, and often have to, replace tp_new with their own
version.  Calling a base type's tp_new when you've defined your own
tp_new at the C level is dangerous.


As for the issue with a subclass's arguments being different, I'm
shocked that anyone at numpy could possibly think bypassing the
subtype's constructor is good idea.


Carl Banks
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Re: condition and True or False

On May 2, 10:14 am, Paul McGuire pt...@austin.rr.com wrote:
 While sifting through some code looking for old x and y or z code
 that might better be coded using y if x else z, I came across this
 puzzler:

     x = boolean expression and True or False

 What is and True or False adding to this picture?  The boolean
 expression part is already evaluating to a boolean, so I don't
 understand why a code author would feel compelled to beat this one
 over the head with the additional and True or False.

 I did a little code Googling and found a few other Python instances of
 this, but also many Lua instances.  I'm not that familiar with Lua, is
 this a practice that one who uses Lua frequently might carry over to
 Python, not realizing that the added and True or False is redundant?

 Other theories?

The person who wrote it was a programmer who fancied himself to be
more clever than he really was.

Convenient though they may be, people always abuse (and often misuse)
these boolean shortcuts, a big reason why I don't like them.  You
never see crap like this in Java.


Carl Banks
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Re: Parser

2010-05-02 Thread Martin v. Loewis

Andreas Löscher wrote:
 Hi,
 I am looking for an easy to use parser. I am want to get an overview
 over parsing and want to try to get some information out of a C-Header
 file.

To get information from a header file, try Tools/scripts/h2py.py

Regards,
Martin
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Re: sometype.new and C subclasses


On 5/2/2010 3:58 PM, Robert Kern wrote:

Well, I think we can change zeros_like() and the rest to work around
this issue. Can you bring it up on the numpy mailing list?

def zeros_like(a):
if isinstance(a, ndarray):
res = numpy.empty(a.shape, a.dtype, order=a.flags.fnc)
res.fill(0)
res = res.view(type(a))
return res
...


I'm having difficulty posting to the NumPy list (both via gmane and 
email) so I'm just going to put this here so it doesn't get lost. 
zeros_like probably needs to call __array_finalize__ for this to work 
properly (it'll cause a segfault for me otherwise):


 def zeros_like(a):
 if isinstance(a, ndarray):
 res = numpy.zeros(a.shape, a.dtype, order=a.flags.fnc)
 res = res.view(type(a))
 res.__array_finalize__(a)
 return res
 ...

- Jim

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Re: condition and True or False

On Sun, 02 May 2010 10:14:44 -0700, Paul McGuire wrote:

 While sifting through some code looking for old x and y or z code that
 might better be coded using y if x else z, I came across this puzzler:
 
 x = boolean expression and True or False
 
 What is and True or False adding to this picture?  The boolean
 expression part is already evaluating to a boolean, so I don't
 understand why a code author would feel compelled to beat this one over
 the head with the additional and True or False.

If boolean expression is already an actual bool, then I can only 
imagine that the author is simply struggling with the concept, in the 
same way that some people write:

if boolean expression == True:
...


If it is any arbitrary object, then x and True or False is just an 
obfuscated way of writing bool(x). Perhaps their code predates the 
introduction of bools, and they have defined global constants True and 
False but not bool. Then they removed the True and False bindings as no 
longer necessary, but neglected to replace the obfuscated conversion.



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ANN: expy 0.6.6 released!

2010-05-02 Thread Yingjie Lan

EXPY is an express way to extend Python!

EXPY provides a way to extend python in an elegant way. For more information 
and a tutorial, see: http://expy.sourceforge.net/

What's new:

1. Special methods can now take @throws decorators.
2. Added convenience macros type_NEW and type_CheckExact for extension 
types.
3. Give warnings of missing Py_INCREF on all methods/functions returning an 
object. 
4. And the responsibility of Py_INCREF is left for the developer.
5. Documentation update.

Cheers,

Yingjie


  
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Re: List size versus list allocation

On Sun, 02 May 2010 18:07:31 +0200, Christian Heimes wrote:

 I'm interested in gathering some statistics on this, and to do so I
 need a way of measuring the list's logical size versus its actual size.
 The first is easy: it's just len(list). Is there some way of getting
 the allocated size of the list?
 
 With Python 2.6 and newer you can use sys.getsizeof() to get the actual
 size of the list object:


Thanks Christian and Peter for your answers. That's very helpful.


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Re: condition and True or False

2010-05-02 Thread Patrick Maupin

On May 2, 12:14 pm, Paul McGuire pt...@austin.rr.com wrote:
 While sifting through some code looking for old x and y or z code
 that might better be coded using y if x else z, I came across this
 puzzler:

     x = boolean expression and True or False

 What is and True or False adding to this picture?  The boolean
 expression part is already evaluating to a boolean, so I don't
 understand why a code author would feel compelled to beat this one
 over the head with the additional and True or False.

 I did a little code Googling and found a few other Python instances of
 this, but also many Lua instances.  I'm not that familiar with Lua, is
 this a practice that one who uses Lua frequently might carry over to
 Python, not realizing that the added and True or False is redundant?

 Other theories?

 -- Paul

I think it's idiomatic -- that it was written by someone who was deep
in thought about actually getting something accomplished, and not
thinking at the level of the details.

As you're actively *looking* for x and y or z I'm sure you'll agree
that we've probably all written lots of stuff like:

x = expression and 'some_prefix' or ''
x = expression and 42 or 0
x = expression and ['Hi, mom!'] or []

When you're in this mode of expression, the only thing that would
really trip you up and make it wrong is if 'some_prefix' or 42 or
['Hi, mom!'] evaluated to False, and then you get the '', 0, or [] you
didn't really want.  So I know that, to the extent I was thinking
deeply about the low level of what I was writing, my mental energy
would be going towards making sure that the second sub-expression
evaluated to true.

So, if you're mentally operating in this mode, and you want True or
False, and you forget, don't think about, or are not cognizant of the
fact that bool() is available, it's pretty obvious what the result is
going to be.  I've probably done it myself a few times, although I
would probably have to be *really* lost in thought in order to do it
when the underlying sub-expression was boolean to start with.

Regards,
Pat
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Re: sometype.new and C subclasses

2010-05-02 Thread Gregory Ewing


James Porter wrote:
Functions like numpy.zeros_like use ndarray.__new__(subtype, 
...) to create new arrays based on the shape of other arrays.


Maybe the real answer to this question is NumPy is doing it wrong


Yes, I think NumPy is doing it wrong, even for subclasses
written in Python. If the subtype has overridden ndarray's
__new__ method, the way NumPy is doing it will skip the
subclass's version of the method.

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Re: condition and True or False

2010-05-02 Thread John Machin

On May 3, 9:14 am, Steven D'Aprano st...@remove-this-
cybersource.com.au wrote:

 If it is any arbitrary object, then x and True or False is just an
 obfuscated way of writing bool(x). Perhaps their code predates the
 introduction of bools, and they have defined global constants True and
 False but not bool. Then they removed the True and False bindings as no
 longer necessary, but neglected to replace the obfuscated conversion.

Or perhaps they are maintaining code that must run on any 2.X. True
and False would be set up conditional on Python version. Writing
expression and True or False avoids a function call.

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Re: ANN: expy 0.6.6 released!

2010-05-02 Thread Yingjie Lan

 Subject: ANN: expy 0.6.6 released!
 To: python list python-list@python.org
 Cc: CAPI Python capi-...@python.org
 Date: Monday, May 3, 2010, 3:24 AM
 EXPY is an express way to extend Python!

 EXPY provides a way to extend python in an elegant way. For
 more information and a tutorial, see: http://expy.sourceforge.net/

I'm using expy in a serious project to wrap an old project written in C and 
deliver it up via www with django. That is why expy is getting improved quickly 
these days. So far, both the project and expy are making good progress hand in 
hand.

Cheers,

Yingjie

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Re: Fast Efficient way to transfer an object to another list

2010-05-02 Thread Bryan

Steven D'Aprano wrote:
 The simplest way to speed the above code up is not to start from the
 beginning each time. That requires two very small changes. And since
 deletions from the front of the list are slow, MRAB's suggestion is also
 a good idea.

Those two speed-ups provide worst-case linear run-time, but as MRAB
astutely noted, his optimization assumes that order is unimportant.
That's a bad assumption for a general extract-from-list function.
Where order does not matter, I'd suspect 'list' was a poor choice of
data type. Here's a general, order-preserving, linear-time version:


def extract(lst, predicate):
 Return items of lst satisfying predicate, deleting them from
lst.

result = []
j = 0
for i in range(len(lst)):
if predicate(lst[i]):
result.append(lst[i])
else:
lst[j] = lst[i]
j += 1
del lst[j:]
return result


# some testing:
for nitems in range(10):
for pred in [lambda x: True,
lambda x: False,
lambda x: x % 2 == 0,
lambda x: x % 2 == 1,
lambda x: x  nitems // 2,
lambda x: x = nitems // 2]:
original = list(range(nitems))
source = original[:]
extracted = extract(source, pred)
assert len(source) + len(extracted) == nitems
assert sorted(source) == source
for n in source:
assert not pred(n)
assert n in original
assert sorted(extracted) == extracted
for n in extracted:
assert pred(n)
assert n in original



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Re: Python dot-equals (syntax proposal)

2010-05-02 Thread Alf P. Steinbach


* Terry Reedy:

* Alf P. Steinbach:

* Aahz:



and sometimes
they rebind the original target to the same object.


At the Python level that seems to be an undetectable null-operation.


If you try t=(1,2,3); t[1]+=3, if very much matters that a rebind occurs.


Testing:

test lang=py3
 t = ([], [], [])
 t
([], [], [])
 t[0] += [blah]
Traceback (most recent call last):
  File stdin, line 1, in module
TypeError: 'tuple' object does not support item assignment
 t
(['blah'], [], [])
 _
/test

Yep, it matters.

Is this change-but-raise-exception a bug?

I seem to have a knack for running into bugs. :-)



Granted one could see something going on in a machine code or byte code
debugger. But making that distinction (doing nothing versus
self-assignment) at the Python level seems, to me, to be meaningless.


Please do not confuse things. Augmented *assignment* must be understood
as assignment. Failure to do so leads (and has lead) newbies into
confusion, and puzzled posts on this list.


OK.

But I think it would be less confusing, less breaking of expectations, if, for 
the example above, += reduced to the functionality of extend(), with no x.



Cheers,  thanks,

- Alf
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Re: Parser

2010-05-02 Thread dmtr

On May 2, 12:54 pm, Andreas Löscher andreas.loesc...@s2005.tu-
chemnitz.de wrote:
 Hi,
 I am looking for an easy to use parser. I am want to get an overview
 over parsing and want to try to get some information out of a C-Header
 file. Which parser would you recommend?

ANTLR
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Re: Parser

2010-05-02 Thread Chris Rebert

On Sun, May 2, 2010 at 10:10 PM, dmtr dchich...@gmail.com wrote:
 On May 2, 12:54 pm, Andreas Löscher andreas.loesc...@s2005.tu-
 chemnitz.de wrote:
 Hi,
 I am looking for an easy to use parser. I am want to get an overview
 over parsing and want to try to get some information out of a C-Header
 file. Which parser would you recommend?

 ANTLR

I don't know if it's that easy to get started with though. The
companion for-pay book is *most excellent*, but it seems to have been
written to the detriment of the normal online docs.

Cheers,
Chris
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Re: Parser

2010-05-02 Thread dmtr


  ANTLR

 I don't know if it's that easy to get started with though. The
 companion for-pay book is *most excellent*, but it seems to have been
 written to the detriment of the normal online docs.

 Cheers,
 Chris
 --http://blog.rebertia.com


IMO ANTLR is much easier to use compared to any other tool simply
because it has excellent GUI (the quality of which is amazing).
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[issue1533] Bug in range() function for large values


Mark Dickinson dicki...@gmail.com added the comment:

Thanks---the new patch looks good.  Pulling the argument conversion out into a 
separate function makes the whole thing much cleaner.

I still have a couple of nits:

 - Please add a comment before get_range_argument indicating
   what it's for.  I'd also consider naming the function something
   more descriptive like 'convert_range_argument' rather than
   'get_range_argument', but I've never been good with names...

 - Good catch about checking the return type of nb_int.  The error
   message should refer to __int__ though, not nb_int:  nb_int
   won't make much sense to most Python users.

 - I notice that get_range_argument steals a reference to arg.  That's
   fine of course, but it's a little bit unusual, so there should be
   a comment pointing that out somewhere.  It *might* be preferable to
   not steal the reference, and just do the usual 'return a new
   reference' thing instead; I know that leads to a little bit
   more boilerplate in handle_range_longs, but I think the code ends
   up clearer, and there won't be surprises for someone who tries to
   reuse the code in get_range_argument for their own conversions.  I
   leave it up to you. :)

 - Please could you also add a test for small arguments for each test
   class?

 - Style nit:  the codebase mostly avoids assignments in 'if' conditions;
   please separate the assignment and the NULL test in lines like
   if (!(ilow = get_range_argument(ilow, start))).  Also,
   if (ilow == NULL) is preferable to if (!ilow).

Thanks again for doing this.

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[issue1533] Bug in range() function for large values


Mark Dickinson dicki...@gmail.com added the comment:

Thinking about it a bit more, I really would prefer get_range_argument not to 
steal a reference.  If I'm reading a bit of C code and encounter something like:

  obj = transform(obj);
  if (obj == NULL) ...

my hindbrain immediately starts fretting that something's wrong, and I have to 
go and ferret out the definition of 'transform' to be sure.  In contrast, 
patterns like:

  temp = transform(obj);
  Py_DECREF(obj);
  obj = temp;
  if (obj == NULL) ...

are so common and familiar in the Python codebase that they don't raise the 
same sort of red flag.

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[issue8533] regrtest: use backslashreplace error handler for stdout


STINNER Victor victor.stin...@haypocalc.com added the comment:

Ok, let's try sys.stderr solution: commited in r80694 (py3k).

If it breaks buildbot outputs, I will revert it and try the second solution.

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[issue8589] test_warnings.CEnvironmentVariableTests.test_nonascii fails under an ascii terminal


STINNER Victor victor.stin...@haypocalc.com added the comment:

The bug only occurs on Mac OS X because file system encoding is hardcoded to 
UTF-8 on this OS and the test is skipped if the file system encoding is ASCII.

But the bug is not specific to test_warnings, as mentionned by R. David Murray: 
#8533 is the real bug. test_warnings is just an example to reproduce it.

I just commited a fix for #8533: it should fix also this issue.

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dependencies: +regrtest: use backslashreplace error handler for stdout

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[issue1533] Bug in range() function for large values


Mark Dickinson dicki...@gmail.com added the comment:

BTW, I've changed the various nb_int should return int object error messages 
in Objects/intobject.c to the more meaningful and accurate message: __int__ 
method should return an integer, in r80695.

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[issue7192] webbrowser.get(firefox) does not work on Mac with installed Firefox

2010-05-02 Thread Ronald Oussoren


Ronald Oussoren ronaldousso...@mac.com added the comment:

Firefox doesn't seem to support a full scripting api, which makes opening tabs 
and windows harder.

I've committed an alternate version of your patch in r80698: This uses 
osascript to open the url instead of the open command. I've also added a 
registration for safari.

The main reason to use osascript instead of just open is that it might be 
possible to add support for opening new tabs or windows later on by adjusting 
the script.

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[issue7192] webbrowser.get(firefox) does not work on Mac with installed Firefox

2010-05-02 Thread Ronald Oussoren


Ronald Oussoren ronaldousso...@mac.com added the comment:

I've ported the change to 3.2 as well.

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[issue8598] test/support: don't use localhost as IPv6 host name


New submission from STINNER Victor victor.stin...@haypocalc.com:

TestIPv6Environment testcase of test_ftplib uses support.HOST as hostname, and 
HOST=localhost. Usually, localhost is the name of 127.0.0.1, but not always 
::1. On Linux, the usual names for ::1 are ip6-localhost or ip6-loopback. My 
internet server provider DNS resolver does not always resolv localhost as 
::1, sometimes it answer 3(NXDOMAIN). Anyway, the name should be resolved by 
the local DNS resolver, not depend on an external (ISP) DNS server.

The simplest solution is to use ::1 instead of localhost ;-)

--
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messages: 104778
nosy: haypo
priority: normal
severity: normal
status: open
title: test/support: don't use localhost as IPv6 host name
versions: Python 2.7, Python 3.2

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[issue8596] crypt blowfish 'ignores' salt


Mark Dickinson dicki...@gmail.com added the comment:

I doubt this is a Python issue, since the crypt function does little more than 
wrap the system crypt function.

What does your man page for crypt say?  Are you sure you're providing a salt 
that the system crypt accepts?

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[issue8598] test/support: don't use localhost as IPv6 host name


STINNER Victor victor.stin...@haypocalc.com added the comment:

Attached patch uses IPV6_HOST='::1'.

--
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Added file: http://bugs.python.org/file17183/support_ipv6_host.patch

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[issue8596] crypt blowfish 'ignores' salt


Changes by Mark Dickinson dicki...@gmail.com:


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status: open - pending

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[issue8598] test/support: don't use localhost as IPv6 host name


STINNER Victor victor.stin...@haypocalc.com added the comment:

Mac OS X 10.6.3 has ::1  localhost.

My Ubuntu 9.10 has ::1  ip6-localhost ip6-loopback but I don't rember if I 
edited this line or not. I don't think so.

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[issue8598] test/support: don't use localhost as IPv6 host name


STINNER Victor victor.stin...@haypocalc.com added the comment:

Debian Sid has ::1 ip6-localhost ip6-loopback localhost.

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[issue8567] decimal module doesn't respect precedence rules for exceptional conditions


Changes by Mark Dickinson dicki...@gmail.com:


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stage: unit test needed - patch review

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[issue8533] regrtest: use backslashreplace error handler for stdout

2010-05-02 Thread Antoine Pitrou


Antoine Pitrou pit...@free.fr added the comment:

Since it may reorder output, I think it's better revert the patch and try the 
other solution. However, I don't think you need to replace sys.stdout at all: 
just output the traceback more carefully.

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[issue8455] buildbot: test_urllib2_localnet failures (Connection refused) on Tiger buildbot


Mark Dickinson dicki...@gmail.com added the comment:

I'm also seeing this on OS X 10.6.  It seems to have started with r80243.

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[issue8455] buildbot: test_urllib2_localnet failures (Connection refused) on Tiger buildbot


Mark Dickinson dicki...@gmail.com added the comment:

To clarify, that last message was about trunk, where this test is failing for 
me since r80243.  Adding 2.7 to the versions.

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[issue8538] Add ConfigureAction to argparse

2010-05-02 Thread Yaniv Aknin


Changes by Yaniv Aknin yaniv.ak...@gmail.com:


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[issue7192] webbrowser.get(firefox) does not work on Mac with installed Firefox

2010-05-02 Thread R. David Murray


R. David Murray rdmur...@bitdance.com added the comment:

issue 8238 notes the problem with autoraise and new on windows.  I believe when 
I looked at that issue that I confirmed that the syntax webbrowser uses on 
Linux to support those options works on windows with the current firefox, even 
though I couldn't find them documented anywhere.  If I'm remembering correctly, 
then I would expect them to work on Mac, as well.

Webbrowser needs to be refactored so that browser specific support is not not 
required to be also platform specific.

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[issue8597] build out-of-line asm on Windows

2010-05-02 Thread Brian Curtin


Changes by Brian Curtin cur...@acm.org:


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[issue3445] Ignore missing attributes in functools.update_wrapper

2010-05-02 Thread July Tikhonov


July Tikhonov july.t...@gmail.com added the comment:

Patch updated: bound and unbound methods, user-defined callable, partial object 
included in test.

By the way,

 [id(abs.__doc__) for i in range(5)]
[140714383081744, 140714383081744, 140714383081744, 140714383081744, 
140714383081744]
 [id(s) for s in [abs.__doc__ for i in range(5)]]
[140714383084040, 140714383082976, 140714383083144, 140714383075904, 
140714383081744]

How it can be explained? Built-in functions (and methods) _sometimes_ return a 
new instance of its '__doc__' (and '__name__'), and sometimes does not.
(I found this trying to include built-in method into the test.)

--
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Added file: 
http://bugs.python.org/file17184/update_wrapper-ignore-missing-attributes.patch

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[issue8599] _execvpe should behaves inconsistently when PATH includes a filename

2010-05-02 Thread Oren Held


New submission from Oren Held o...@held.org.il:

A. Description
When running os._execvpe with a relative pathname that does not exist, I'd 
expect to get ENOENT error. But there is an edge case in which Python throws 
ENOTDIR error - when the LAST element in PATH is a regular file (e.g. /bin/ls). 
This case is caused by a sysadmin mistake, but it may happen, as in the system 
on which I've encountered this bug.

B. Explanation + How to reproduce:
Consider the following case:
PATH=/bin:/bin/ls # Last part is a filename instead of a directory
 import os; os.execvp(blabla, [])
Throws: OSError: [Errno 20] Not a directory

Now, consider a similar but differently-ordered PATH:
PATH=/bin/ls:/bin # *First* part is a filename instead of a directory
 import os; os.execvp(blabla, [])
Throws: OSError: [Errno 2] No such file or directory


C. Why this behavior is not good:
First, IMO there is a certain problem here - differently ordered PATH shouldn't 
throw different exception. In both cases the executable was not found in PATH, 
both cases are the same for this matter.

Second, the unix shell (e.g. bash) faces the same issue, and behaves 
differently. It'll return command not found to stdout for both ENOENT and 
ENOTDIR cases, regardless of the element order in PATH.


D. My recommendation
I'd recommend throwing ENOENT even when ENODIR is thrown for some paths. I am 
not sure what's the least-evil way to do it, I've been thinking of the 
following patch, but it's not working because it depends on strerror. It also 
looks kinda ugly:

--- os.py.old   2010-05-02 17:41:21.481909804 +0300
+++ os.py   2010-05-02 18:03:11.261872651 +0300
@@ -386,7 +386,7 @@
 saved_tb = tb
 if saved_exc:
 raise error, saved_exc, saved_tb
-raise error, e, tb
+raise error, error(errno.ENOENT, os.strerror(errno.ENOENT)), tb # DOESNT 
WORK, no access to os.strerror from here
 
 # Change environ to automatically call putenv() if it exists
 try:

--
components: Library (Lib)
messages: 104788
nosy: Oren_Held
priority: normal
severity: normal
status: open
title: _execvpe should behaves inconsistently when PATH includes a filename
type: behavior
versions: Python 2.6

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[issue8599] _execvpe behaves inconsistently when PATH includes a filename

2010-05-02 Thread Oren Held


Changes by Oren Held o...@held.org.il:


--
title: _execvpe should behaves inconsistently when PATH includes a filename - 
_execvpe behaves inconsistently when PATH includes a filename

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[issue8599] _execvpe behaves inconsistently when PATH includes a filename

2010-05-02 Thread R. David Murray


R. David Murray rdmur...@bitdance.com added the comment:

The python functions are thin wrappers around the system calls, and are 
reporting the result of calling the corresponding system call.  The fact that 
the shell chooses to catch both errors and report a single one would be 
equivalent to, say, the cmd module doing something similar.  It would not be 
appropriate for the os module to combine the distinct errors into one.

--
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resolution:  - invalid
stage:  - committed/rejected
status: open - closed

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[issue8597] build out-of-line asm on Windows

2010-05-02 Thread Stefan Krah


Stefan Krah stefan-use...@bytereef.org added the comment:

I think this is a duplicate of issue 7546.

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type: behavior - feature request

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[issue8598] test/support: don't use localhost as IPv6 host name

2010-05-02 Thread R. David Murray


R. David Murray rdmur...@bitdance.com added the comment:

All of my Gentoo systems except one have localhost on the ::1 line.  The one 
that doesn't hasn't been updated in several years.  That one has the same entry 
for ::1 as your Ubuntu.

The FreeBSD 6.3 box I have access to has localhost on the ::1 line.

It has long been true that there are test failures if the testing system cannot 
resolve its own hostname, which often requires fixing /etc/hosts on linux 
systems.  You could call this bug a local system configuration error, too, but 
whether or not that is politic depends on whether or not there are in fact 
standard distributions that don't have localhost on the ::1 line.

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[issue8597] build out-of-line asm on Windows

2010-05-02 Thread Tarek Ziadé


Tarek Ziadé ziade.ta...@gmail.com added the comment:

Distutils is frozen, switching to distutils2

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[issue7546] msvc9compiler.py: add .asm extension

2010-05-02 Thread Tarek Ziadé


Tarek Ziadé ziade.ta...@gmail.com added the comment:

Distutils is frozen, switching to distutils2

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[issue2091] file accepts 'rU+' as a mode

2010-05-02 Thread Brett Cannon


Changes by Brett Cannon br...@python.org:


--
keywords: +needs review
stage: patch review - commit review

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[issue8533] regrtest: use backslashreplace error handler for stdout


STINNER Victor victor.stin...@haypocalc.com added the comment:

As expected, the patch doesn't work: it randomize the output order :-(

I checked sparc Ubuntu 3.x: the output order is correct. test_xxx lines are 
written to stdout, FAIL: ... + traceback are written to stderr, and the lines 
are written in the right order.

But it failed on x86 Tiger 3.x :
http://www.python.org/dev/buildbot/3.x/builders/x86 Tiger 
3.x/builds/130/steps/test/logs/stdio
http://www.python.org/dev/buildbot/3.x/builders/x86 Tiger 
3.x/builds/131/steps/test/logs/stdio

When a test is reexecuted in verbose mode, the output is written in red (why 
not, but it was not the case before my commit), and the stdout and stderr are 
in a mixed.

--

antoine just output the traceback more carefully.

Encode the traceback by hand would be possible, but it's more complex. A 
possible solution would be to write the output to a StringIO, encode unicode to 
bytes using the right encoding and backslashreplace error handler, and write 
the result to stdout. But I don't like buffering the output because the 
buildbot may hung for different reasons (search in the bug tracker for 
test_multiprocessing or test_subprocess...) and the buildbot master may 
consider the buildbot as dead (no new output since xxx seconds, whereas it's 
writing to a buffer).

--

I prefer my first simple idea: use backslashreplace error handler for stdout. 
Let's try: r80703. This commit reverts my previous commit, apply 
regrtest_stdout_backslashreplace.patch + a fix for multiprocessing mode 
(regrtest.py -j ...).

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[issue8583] Hardcoded namespace_separator in the cElementTree.XMLParser

2010-05-02 Thread Stefan Behnel


Stefan Behnel sco...@users.sourceforge.net added the comment:

There is at least one valid use case: code that needs to deal with HTML and 
XHTML currently has to normalise the tag names in some way, which usually means 
that it will want to remove the namespaces from XHTML documents to make it look 
like plain HTML. It would be nice if the library could do this efficiently 
right in the parser by simply removing all namespace declarations. However, 
this doesn't really apply to (c)ElementTree where the parser does not support 
HTML parsing.

I'm -1 on the interface that the proposed patch adds. The keyword argument name 
and its semantics are badly chosen. A boolean flag will work much better.

The proposed feature will have to be used with great care by users. Code that 
depends on it is very fragile and will fail when an input document uses 
unexpected namespaces, e.g. to embed foreign content, or because it is actually 
written in a different XML language that just happens to have similar local tag 
names. This kind of code is rather hard to fix, as fixing it means that it will 
stop accepting documents that previously passed without problems. Rejecting 
broken input early is a virtue.

All in all, I'm -0.5 on this feature as I'd expect most use cases to be 
premature optimisations with potentially dangerous side effects more than 
anything else.

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[issue8598] test/support: don't use localhost as IPv6 host name


STINNER Victor victor.stin...@haypocalc.com added the comment:

Oh, I forgot to copy/paste a test_ftplib failure:
==
ERROR: test_makeport (test.test_ftplib.TestIPv6Environment)
--
Traceback (most recent call last):
  File /home/SHARE/SVN/py3k/Lib/test/test_ftplib.py, line 561, in setUp
self.server = DummyFTPServer((HOST, 0), af=socket.AF_INET6)
  File /home/SHARE/SVN/py3k/Lib/test/test_ftplib.py, line 213, in __init__
self.bind(address)
  File /home/SHARE/SVN/py3k/Lib/asyncore.py, line 329, in bind
return self.socket.bind(addr)
socket.gaierror: [Errno -5] No address associated with hostname

==
ERROR: test_transfer (test.test_ftplib.TestIPv6Environment)
--
Traceback (most recent call last):
  File /home/SHARE/SVN/py3k/Lib/test/test_ftplib.py, line 561, in setUp
self.server = DummyFTPServer((HOST, 0), af=socket.AF_INET6)
  File /home/SHARE/SVN/py3k/Lib/test/test_ftplib.py, line 213, in __init__
self.bind(address)
  File /home/SHARE/SVN/py3k/Lib/asyncore.py, line 329, in bind
return self.socket.bind(addr)
socket.gaierror: [Errno -5] No address associated with hostname

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[issue4687] GC stats not accurate because of debug overhead


Tres Seaver tsea...@agendaless.com added the comment:

The patch looks obviously correct to me.

I can confirm that the patch applies cleanly both to the trunk and to the 
'release26-maint' branch, and that the 'test_gc' tests pass in both cases after 
applying it and rebuilding.

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[issue4687] GC stats not accurate because of debug overhead


Changes by Tres Seaver tsea...@agendaless.com:


--
versions: +Python 2.6

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[issue4265] shutil.copyfile() leaks file descriptors when disk fills


Tres Seaver tsea...@agendaless.com added the comment:

This bug exists on Python 2.6, too.

It seems to me that the right solution here is to use both opened files as 
context managers.  See attached patch (made against the release26-maint branch).

The patch also cleans up the old-style exception signature in the precondition 
check.

--
keywords: +patch
nosy: +tseaver
Added file: http://bugs.python.org/file17185/issue4265_shutil_copyfile.patch

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[issue4265] shutil.copyfile() leaks file descriptors when disk fills