Re: [Python-Dev] my 2.5 checkins
I reverted both changes. They can be re-applied after the 2.5 is unfrozen. -- n On 4/15/07, Anthony Baxter <[EMAIL PROTECTED]> wrote: > On Saturday 14 April 2007 10:07, Kristján Valur Jónsson wrote: > > Hello all. > > I made two checkins to the 25 maintainance branch before Martin > > kindly pointed out to me that it is frozen. These are quite > > simple fixes to real crashes I have experienced. The fix in > > frameobject.c will be necessary if you work with opcodes > 128, > > which we routinely do at CCP J. Security through opcode > > randomization Anyway, just let me know if you like me to roll > > them back. > > I really, really, really don't want to cut another release > candidate. These fixes don't strike me as critical enough to need > that - and I'm not happy to do the release and just hope. I'll roll > them all back. > > Anthony > -- > Anthony Baxter <[EMAIL PROTECTED]> > It's never too late to have a happy childhood. > ___ > Python-Dev mailing list > Python-Dev@python.org > http://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: > http://mail.python.org/mailman/options/python-dev/nnorwitz%40gmail.com > ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] my 2.5 checkins
On Saturday 14 April 2007 10:07, Kristján Valur Jónsson wrote: > Hello all. > I made two checkins to the 25 maintainance branch before Martin > kindly pointed out to me that it is frozen. These are quite > simple fixes to real crashes I have experienced. The fix in > frameobject.c will be necessary if you work with opcodes > 128, > which we routinely do at CCP J. Security through opcode > randomization Anyway, just let me know if you like me to roll > them back. I really, really, really don't want to cut another release candidate. These fixes don't strike me as critical enough to need that - and I'm not happy to do the release and just hope. I'll roll them all back. Anthony -- Anthony Baxter <[EMAIL PROTECTED]> It's never too late to have a happy childhood. ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Some new additions to functools
On 4/15/07, SevenInchBread <[EMAIL PROTECTED]> wrote: [...] > -- > "What's money? A man is a success if he gets up in the morning and goes to > bed at night and in between does what he wants to do." ~ Bob Dylan If you ask me, SevenInchBread (not her real name) is a Troll. Let her prove she isn't. -- --Guido van Rossum (home page: http://www.python.org/~guido/) ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] functools additions
On Sun, 15 Apr 2007 18:18:16 -0400, SevenInchBread <[EMAIL PROTECTED]> wrote: >>>Do you have commit access? What's your real name? >I prefer to remain pseudonymous, and I don't have commit access. > >Yeah... they're not terribly useful - more or less there for the sake of >being there. Batteries included and all that > Please discuss this on the python-ideas list before bringing it up on python-dev. Jean-Paul ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] functools additions
> def cat(x): return x > > def multimap(func, s, n=2): > assert n > 0, "n must be positive" > return (map(func, seq) > if n == 1 else > map(lambda x: multimap(func, x, n-1), > seq)) > > def multifilter(func, s, n=2): > return multimap(lambda x: filter(func, x), s, n-1) > > def multireduce(func, s, n=2): > return multimap(lambda x: reduce(func, x), s, n-1) > > class nullfunc(object): > def __call__(self, *a, **k): return self > def __getattr(self, name): return getattr(None, name) Could you describe what these functions do? Preferably with examples that demonstrates that they are useful. -- mvh Björn ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] functools additions
Do you have commit access? What's your real name? I prefer to remain pseudonymous, and I don't have commit access. Yeah... they're not terribly useful - more or less there for the sake of being there. Batteries included and all that ...but now I've got a more useful idea for a function wrapper around predicate functions to make them a little more functionally inclined. Something like... @predicate def hasnext(x): return hasattr(x, "next") @predicate def hasiter(x): return hasattr(x, "__iter__") isiterable = hasnext or hasiter #or/and/not operators construct new predicate functions isEmptyIterable = isiterable and not predicate(bool) isgenerator = isiterable and (lambda x: hasattr(x, "send") and hasattr(x, "throw")) filter(isgenerator or callable, SomeSequence) -- "What's money? A man is a success if he gets up in the morning and goes to bed at night and in between does what he wants to do." ~ Bob Dylan ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Python 2.5.1c1 pickle problem
Hi Raymond, Thanks for the detailed explanation! > I'm not sure what your code was doing where the bugfix would cause > breakage. If its __getitem__() override returned a meaningful value > for each element in obj.keys(), then it should have worked fine. Of > course, if it was raising an exception or triggering a side-effect, > then one could argue that the bugfix was working as intended by > allowing the subclasser to affect how the base class goes about its > business. It wasn't actually my own code, but that of a colleague. His __getitem__() override is below. It fails because __getitem__() is called with the wrong type of argument (plain int instead of a list of atoms). I'm not sure it presents a convincing use case. I would have used composition instead of inheritance in the same situation. I don't feel competent to join the discussion about the changes in the pickling behavior, but I feel quite strongly that such a change should not be introduced in a bug-fix release. Ralf def __getitem__(self, atoms): LIST = [] for atom in atoms: attr = 'index' if hasattr(atom, 'unique_index'): attr = 'unique_index' LIST.append(getattr(atom, attr)) key1 = tuple(LIST) LIST.reverse() key2 = tuple(LIST) rc = None try: rc = dict.__getitem__(self, key1) except KeyError, e: pass try: rc = dict.__getitem__(self, key2) except KeyError, e: pass return rc __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
[Python-Dev] Py3: function signatures, type checking, and related crap
People seem to be pushing for a consistent method for checking the "x-ness"
of objects (that is, interfaces that the object implements).
So I present an idea for a simple and straightforward type that provides a
way to construct descriptions of object structures, and I'd like some help
expanding it into a useful extension to Python's standard set of utilities.
Its a basic constructor that produces callable interface-checking predicates
(which can be use in things such as list comprehensions, filter, if
statements, or even a new syntax for function signatures that allows for
automatic interface-checking). These predicates check that an object matches
the behavior described by the constructor . Since I can't think of a name
for this constructor, and because I've never liked the term "interface",
I'll just call it "can".
Can takes an arbitrary number of keyword arguments and produces a callable
object. The keys represent object attributes, while the values are
behavior-checking predicates like the ones produced by can. Since the can
constructor produces an object that can in turn be used in other can
constructors, using previously defined interfaces in new constructions is
fairly straight-forward
callable = can(__call__ = object)#Returns an object that describes
objects with a __call__ attribute
readable = can(read = callable)
# ...with a callable read attribute
writable = can(write = callable)
# ...with a callable write attribute
#a join operator can be used to combine can objects...
#...for now I'll just use "and" and "or" to represent them.
isfilelike = readable and writable #returns an object that matches any
type that is described
#by both readable and writable
IOable = readable or writable #any type that is readable or
writable
objects that are constructed with can, when called, return True or False
based on whether or not the passed object matches the behavior described.
callable(hash) #returns True - as it would in the current version
of Python.
Here's some more nifty examples:
iterable = can(__iter__=callable) or can(next=callable)
hashable = can(__hash__=callable)
completefile = isfilelike and iterable and can(fileno=callable,
close=callable)
def outlines(f, seq):
"""Outputs a sequence of lines to a file-like object"""
assert isfilelike(f), "%r is not a file-like object." % f
assert isiterable(seq), "%r must be iterable" % seq
f.write("\n".join(seq))
#a trivial example... you'd get similar error messages from Python
builtins even without the assertions.
As it stands, I don't think that this deserves to be in Python - but I think
the basic premise could be used as a foundation for better things.
--
"What's money? A man is a success if he gets up in the morning and goes to
bed at night and in between does what he wants to do." ~ Bob Dylan
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Re: [Python-Dev] Some new additions to functools
On 4/15/07, SevenInchBread <[EMAIL PROTECTED]> wrote: > So I've cooked up some very simple functions to add to functools - to expand > it into a more general-purpose module. > > def cat(x): return x > > class nullfunc(object): > def __call__(self, *args, **kargs): return self > def __getattr__(self, name):return getattr(None, name) > > def multimap(func, seq, n=2): > assert n > 0, "n must be positive" > if n == 1: return map(func, seq) > else: return map(lambda x: multimap(func, x, n-1), seq) > > def multifilter(func, seq, n=2): > return multimap(lambda x: filter(func, x), seq, n-1) > > def multireduce(func, seq, n=2): > return multimap(lambda x: reduce(func, x), seq, n-1) -0 for cat (renamed to 'identity'), -1 for the rest. I've occasionally wanted multimap but only in the default case where it is simpler to be explicit. -- Paul Hankin ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] functools additions
> So if it's alright with the privledged folk - I'd like to commit > these minor (and probably non-controversial) additions to the functools > module. Do you have commit access? What's your real name? -1 on these additions. If lambda x:x would be added, it should be named "identity", not "cat" (if that name is meant to raise associations with the Unix cat(1) utility, please understand that "cat" is short for "concatenate"). Regards, Martin ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Some new additions to functools
SevenInchBread <[EMAIL PROTECTED]> wrote: > So I've cooked up some very simple functions to add to functools - to expand > it into a more general-purpose module. [snip] I don't use a functional approach very often, but I haven't ever had a case where I would want or need to use any of the functions you provide. Does anyone else think that any or all of these would be useful? > A better place to put some of these functions might be __builtin__, so you > don't have to waste time importing something as basic as cat. We do not arbitrarily add functions to builtins. The general approach that most people have is to *reduce* the number of builtins, not increase them. Generally, -.5 on the functions/objects you provide (I haven't used them, but I'm reserving a -1 or -0 for if people have other opinions). -1000 on adding them to the builtins. - Josiah ___ Python-Dev mailing list [EMAIL PROTECTED] http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Extended buffer PEP
Greg Ewing wrote: > Travis Oliphant wrote: > >> Carl Banks wrote: >> > I'd like to see it accept a flags argument over what kind of buffer >> > it's allowed to return. I'd rather not burden the user to check >> all > the entries in bufferinfo to make sure it doesn't get something >> > unexpected. >> Yes, I agree. We had something like that at one point. > > > Maybe this could be handled in an intermediate layer > between the user and implementor of the interface, > i.e. the user calls > > PyBuffer_GetBuffer(obj, &info, flags); > > the object's tp_getbufferinfo just gets called as > > getbufferinfo(self, &info) > > and PyBuffer_GetBuffer then checks that the result > conforms to the requested feature set. This would > relieve users of the interface from having to check > that themselves, while not requiring implementors > to be burdened with it either. I like this strategy.Then, any intermediate buffering (that prompted the killed release-buffer object in the protocol) could be handled in this layer as well. I also like the idea of passing something to the getbuffer call so that exporters can do less work if some things are not being requested, but that the exporter should be free to ignore the flag and always produce everything. -Travis ___ Python-Dev mailing list [EMAIL PROTECTED] http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
[Python-Dev] Extended buffer PEP
Here is my "final" draft of the extended buffer interface PEP. For those who have been following the discussion, I eliminated the releaser object and the lock-buffer function. I decided that there is enough to explain with the new striding and sub-offsets without the added confusion of releasing buffers, especially when it is not clear what is to be gained by such complexity except a few saved lines of code. The striding and sub-offsets, however, allow extension module writers to write code (say video and image processing code or scientific computing code or data-base processing code) that works on any object exposing the buffer interface. I think this will be of great benefit and so is worth the complexity. This will take some work to get implemented for Python 3k. I could use some help with this in order to speed up the process. I'm working right now on the extensions to the struct module until the rest is approved. Thank you for any and all comments: -Travis :PEP: XXX :Title: Revising the buffer protocol :Version: $Revision: $ :Last-Modified: $Date: $ :Authors: Travis Oliphant <[EMAIL PROTECTED]>, Carl Banks <[EMAIL PROTECTED]> :Status: Draft :Type: Standards Track :Content-Type: text/x-rst :Created: 28-Aug-2006 :Python-Version: 3000 Abstract This PEP proposes re-designing the buffer interface (PyBufferProcs function pointers) to improve the way Python allows memory sharing in Python 3.0 In particular, it is proposed that the character buffer portion of the API be elminated and the multiple-segment portion be re-designed in conjunction with allowing for strided memory to be shared. In addition, the new buffer interface will allow the sharing of any multi-dimensional nature of the memory and what data-format the memory contains. This interface will allow any extension module to either create objects that share memory or create algorithms that use and manipulate raw memory from arbitrary objects that export the interface. Rationale = The Python 2.X buffer protocol allows different Python types to exchange a pointer to a sequence of internal buffers. This functionality is *extremely* useful for sharing large segments of memory between different high-level objects, but it is too limited and has issues: 1. There is the little used "sequence-of-segments" option (bf_getsegcount) that is not well motivated. 2. There is the apparently redundant character-buffer option (bf_getcharbuffer) 3. There is no way for a consumer to tell the buffer-API-exporting object it is "finished" with its view of the memory and therefore no way for the exporting object to be sure that it is safe to reallocate the pointer to the memory that it owns (for example, the array object reallocating its memory after sharing it with the buffer object which held the original pointer led to the infamous buffer-object problem). 4. Memory is just a pointer with a length. There is no way to describe what is "in" the memory (float, int, C-structure, etc.) 5. There is no shape information provided for the memory. But, several array-like Python types could make use of a standard way to describe the shape-interpretation of the memory (wxPython, GTK, pyQT, CVXOPT, PyVox, Audio and Video Libraries, ctypes, NumPy, data-base interfaces, etc.) 6. There is no way to share discontiguous memory (except through the sequence of segments notion). There are two widely used libraries that use the concept of discontiguous memory: PIL and NumPy. Their view of discontiguous arrays is different, though. The proposed buffer interface allows sharing of either memory model. Exporters will use only one approach and consumers may choose to support discontiguous arrays of each type however they choose. NumPy uses the notion of constant striding in each dimension as its basic concept of an array. With this concept, a simple sub-region of a larger array can be described without copying the data. T Thus, stride information is the additional information that must be shared. The PIL uses a more opaque memory representation. Sometimes an image is contained in a contiguous segment of memory, but sometimes it is contained in an array of pointers to the contiguous segments (usually lines) of the image. The PIL is where the idea of multiple buffer segments in the original buffer interface came from. NumPy's strided memory model is used more often in computational libraries and because it is so simple it makes sense to support memory sharing using this model. The PIL memory model is sometimes used in C-code where a 2-d array can be then accessed using double pointer indirection: e.g. image[i][j]. The buffer interface should allow the object to export either of these memory models. Consumers are free to either require contiguous memory or write code to handle one or both
[Python-Dev] Summary of Tracker Issues
ACTIVITY SUMMARY (03/20/07 - 03/27/07) Tracker at http://bugs.python.org/ To view or respond to any of the issues listed below, click on the issue number. Do NOT respond to this message. 1646 open ( +2) / 8583 closed ( +1) / 10229 total ( +3) Average duration of open issues: 747 days. Median duration of open issues: 695 days. Open Issues Breakdown open 1646 ( +2) pending 0 ( +0) Issues Created Or Reopened (3) __ Buy Tramadol online 03/25/07 http://bugs.python.org/issue1023created conor2k Testing bugs.python.org domain 03/26/07 CLOSED http://bugs.python.org/issue1024created izak Test issue 03/26/07 http://bugs.python.org/issue1025created loewis Issues Now Closed (2) _ Personal loans. Bad credit personal loans. Unsecured personal l1 days http://bugs.python.org/issue1002dubois Testing bugs.python.org domain 0 days http://bugs.python.org/issue1024izak ___ Python-Dev mailing list [EMAIL PROTECTED] http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Extended Buffer Interface/Protocol
Carl Banks wrote: > Tr > ITSM that we are using the word "view" very differently. Consider > this example: > > A = zeros((100,100)) > B = A.transpose() You are thinking of NumPy's particular use case. I'm thinking of a generic use case. So, yes I'm using the word view in two different contexts. In this scenario, NumPy does not even use the buffer interface. It knows how to transpose it's own objects and does so by creating a new NumPy object (with it's own shape and strides space) with a data buffer pointed to by "A". Yes, I use the word "view" for this NumPy usage, but only in the context of NumPy. In the PEP, I've been using the word "view" quite a bit more generically. So, I don't think this is a good example because A.transpose() will never call getbuffer of the A object (it will instead use the known structure of NumPy directly). So, let's talk about the generic situation instead of the NumPy specific one. > > I'd suggest the object returned by A.getbuffer should be called the > "buffer provider" or something like that. I don't care what we call it. I've been using the word "view" because of the obvious analogy to my use of view in NumPy. When I had envisioned returning an actual object very similar to a NumPy array from the buffer interface it made a lot of sense to call it a view. Now, I'm fine to call it "buffer provider" > > For the sake of discussion, I'm going to avoid the word "view" > altogether. I'll call A the exporter, as before. B I'll refer to as > the requestor. The object returned by A.getbuffer is the provider. Fine. Let's use that terminology since it is new and not cluttered by other uses in other contexts. > Having thought quite a bit about it, and having written several > abortive replies, I now understand it and see the importance of it. > getbuffer returns the object that you are to call releasebuffer on. > It may or may not be the same object as exporter. Makes sense, is > easy to explain. Yes, that's exactly all I had considered it to be. Only now, I'm wondering if we need to explicitly release a lock on the shape, strides, and format information as well as the buffer location information. > > It's easy to see possible use cases for returning a different object. > A hypothetical future incarnation of NumPy might shift the > responsibility of managing buffers from NumPy array object to a hidden > raw buffer object. In this scenario, the NumPy object is the > exporter, but the raw buffer object the provider. > > Considering this use case, it's clear that getbuffer should return the > shape and stride data independently of the provider. The raw buffer > object wouldn't have that information; all it does is store a pointer > and keep a reference count. Shape and stride is defined by the exporter. So, who manages the memory to the shape and strides and isptr arrays? When a provider is created do these need to be created so that the shape and strides arrays are never deallocated when in use. The situation I'm considering is if you have a NumPy array of shape (2,3,3) which you then obtain a provider of (presumably from another package) and it retains a lock on the memory for a while. Should it also retain a lock on the shape and strides array? Can the NumPy array re-assign the shape and strides while the provider has still not been released? I would like to say yes, which means that the provider must supply it's own copy of shape and strides arrays. This could be the policy. Namely, that the provider must supply the memory for the shape, strides, and format arrays which is guaranteed for as long as a lock is held. In the case of NumPy, that provider could create it's own copy of the shape and strides arrays (or do it when the shape and strides arrays are re-assigned). > >>> Second question: what happens if a view wants to re-export the >>> buffer? Do the views of the buffer ever change? Example, say you >>> create a transposed view of a Numpy array. Now you want a slice of >>> the transposed array. What does the transposed view's getbuffer >>> export? >> >> >> Basically, you could not alter the internal representation of the >> object while views which depended on those values were around. >> >> In NumPy, a transposed array actually creates a new NumPy object that >> refers to the same data but has its own shape and strides arrays. >> >> With the new buffer protocol, the NumPy array would not be able to >> alter it's shape/strides/or reallocate its data areas while views >> were being held by other objects. > > > But requestors could alter their own copies of the data, no? Back to > the transpose example: B itself obviously can't use the same "strides" > array as A uses. It would have to create its own strides, right? I don't like this example because B does have it's own strides because it is a complete NumPy array. I think we are talking about the same thing and tha
Re: [Python-Dev] Extended Buffer Interface/Protocol
Greg Ewing wrote: > But since the NumPy object has to know about the provider, > it can simply pass the release call on to it if appropriate. > I don't see how this case necessitates making the release call > on a different object. > > I'm -1 on involving any other objects or returning object > references from the buffer interface, unless someone can > come up with a use case which actually *requires* this > (as opposed to it just being something which might be > "nice to have"). The buffer interface should be Blazingly > Fast(tm), and messing with PyObject*s is not the way to > get that. The current proposal would be fast but would be more flexible for objects that don't have a memory representation that can be shared unless they create their own "sharing object" that perhaps copies the data into a contiguous chunk first. Objects which have memory which can be shared perfectly through the interface would simply pass themselves as the return value (after incrementing their "extant buffers" count by one). > > Seems to me the lock should apply to *everything* returned > by getbuffer. If the requestor is going to iterate over the > data, and there are multiple dimensions, surely it's going to > want to refer to the shape and stride info at regular intervals > while it's doing that. Requiring it to make its own copy > would be a burden. There are two use cases that seem to be under discussion. 1) When you want to apply an algorithm to an arbitrary object that exposes the buffer interface 2) When you want to create an object that shares memory with another object exposing the buffer interface. These two use cases have slightly different needs. What I want to avoid is forcing the exporting object to be unable to change its shape and strides just because an object is using the memory for use case #2. I think the solution that states the shape and strides information are only guaranteed valid until the GIL is released is sufficent. Alternatively, one could release the shape and strides and format separately from the memory with a flag as a second argument to releasebuffer. -Travis > > -- > Greg > > ___ Python-Dev mailing list [EMAIL PROTECTED] http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] new subscriber looking for grunt work
> I'll be as brief as possible. The welcome message to this list suggested > that I post a brief introduction of myself, so here it goes. I've been > programming for about 10 years now (7 professionally). I would rank > myself as a moderate programmer always looking to improve, and > would like to help on this project in whatever way I can. I'll be trolling > for grunt work and any documentation that needs to be done while > I get the hang of things around here. Hi Sergio, an activity that is always worthwhile is bug and patch review. Pick a patch or a bug report that hasn't seen any feedback (there are, unfortunately, plenty of them), and try to analyse it. See http://mail.python.org/pipermail/python-dev/2002-November/029831.html for an older article of what these activites involve. Regards, Martin ___ Python-Dev mailing list [EMAIL PROTECTED] http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
[Python-Dev] functools additions
So if it's alright with the privledged folk - I'd like to commit these minor (and probably non-controversial) additions to the functools module. def cat(x): return x def multimap(func, s, n=2): assert n > 0, "n must be positive" return (map(func, seq) if n == 1 else map(lambda x: multimap(func, x, n-1), seq)) def multifilter(func, s, n=2): return multimap(lambda x: filter(func, x), s, n-1) def multireduce(func, s, n=2): return multimap(lambda x: reduce(func, x), s, n-1) class nullfunc(object): def __call__(self, *a, **k): return self def __getattr(self, name): return getattr(None, name) cat is a generic identity function - useful for some higher-order functions to specify a function that "does nothing". multimap, multifilter, and multireduce, are all multi-dimensional versions of map, filter, and reduce. nullfunc is a special callable object that emulates the failed callable None proposal - which wasn't really a good idea, but would have been more useful as a different object apart from None. you could probably even put cat in __builtins__ - so you don't need to waste effort importing such a trivial function. --. "What's money? A man is a success if he gets up in the morning and goes to bed at night and in between does what he wants to do." ~ Bob Dylan ___ Python-Dev mailing list [EMAIL PROTECTED] http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
[Python-Dev] Some new additions to functools
So I've cooked up some very simple functions to add to functools - to expand it into a more general-purpose module. def cat(x): return x class nullfunc(object): def __call__(self, *args, **kargs): return self def __getattr__(self, name):return getattr(None, name) def multimap(func, seq, n=2): assert n > 0, "n must be positive" if n == 1: return map(func, seq) else: return map(lambda x: multimap(func, x, n-1), seq) def multifilter(func, seq, n=2): return multimap(lambda x: filter(func, x), seq, n-1) def multireduce(func, seq, n=2): return multimap(lambda x: reduce(func, x), seq, n-1) In an expression, cat achieves the effect of doing nothing - which makes it a nice default value for some filter-like functions. It's not a huge improvement - lambda x: x is almost as trivial to define, but I think it would be nice to have a standard identity function that all of Python could recognize. nullfunc is a function that *chomps* away at its input while otherwise retaining the properties of None - much like the recently proposed callable None - except not as disasterous to existing practices and potentially more useful as an optional behavior. This is something that cannot be as quickly implemented as the cat function. multimap is a multi-dimensional mapping function that recursively decends a sequence and applies a function to the data within. multifilter is a multi-dimensional filter function that recursively descends a sequence and applies a function to the data within multireduce - well... you get the idea A better place to put some of these functions might be __builtin__, so you don't have to waste time importing something as basic as cat. -- "What's money? A man is a success if he gets up in the morning and goes to bed at night and in between does what he wants to do." ~ Bob Dylan ___ Python-Dev mailing list [EMAIL PROTECTED] http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
