Re: Difference between 'function' and 'method'
On Mar 7, 1:34 pm, [EMAIL PROTECTED] wrote: On Mar 7, 6:44 am, Sion Arrowsmith [EMAIL PROTECTED] wrote: Gabriel Genellina [EMAIL PROTECTED] wrote: En Thu, 06 Mar 2008 23:46:43 -0200, [EMAIL PROTECTED] escribi�: [ ... ] You may look at the SimpleXMLRPCServer class and see how it implements introspection. It's rather easy (and doesn't require metaclasses nor decorators nor any other fancy stuff; I think it works the same since Python 2.1). Apparently you're doing a similar thing, but using pickles instead of xmlrpc. It's not that difficult to graft pickles into SimpleXMLRPCServer -- I've done it, and if you're trying to sling large data structures over the connection it's a massive performance win (even with sgmlop in place to speed up XML parsing). her nu becomeþ se bera eadward ofdun hlæddre heafdes bæce bump bump bump Yeah, but I'd be grafting a non-blocking RPC sequence too. -Instantiate- attributes of ISS upon instantiation. class C: d= D c= C() assert isinstance( c.d, D ) assert c.d is c.d Which ones? Two options: instantiate all attributes, or ones with a certain property, such as name or superclass. class C: inst_d= D #actually gets bound to 'd', optionally class C: d= inst( D ) I think what I'm looking for is an attribute wrapper. class C: @inst d= D But the closest the syntax goes is: class C: class d( D ): pass (which takes us back to one of Steven's posts some days ago.) ( def f(x=None):/class C:/x= X/return C. ) and the d= inst( D ) solution.) You either need to assign something to assign something to its name, class C: d= X or declare it, but that only allows def and class statements (correct?). class C: attr d: D is ideal. -- http://mail.python.org/mailman/listinfo/python-list
Re: Difference between 'function' and 'method'
En Thu, 06 Mar 2008 23:46:43 -0200, [EMAIL PROTECTED] escribi�: oss.message is a abstraction class that writes the method name into a string, then sends it to OSS... outgoingserver or serverside. Now that I'm writing it, and this is important, -to- the -newsgroup-, I realize you could do it with a simple wrapper... include the function name in parameters and call the pickler and send. OSS then looks like this: def something_happens( *ar ): self.user_act( something_about( *ar ) ) So the message.out() instance pickles ( 'user_act', ar ) and sends it. Then iss.incoming receives it, unpickles that string, gets 'user_act' from self, and invokes. The cool part is the declaration of user_act= message.out(), which uses a metaclass to assign its own name, and returns a function which includes the object in its signature. Cool. Yes it's working and a little slack. However-: this is the cool part. I'd like messages to know which instance they came from, and perform the sending receiving encapsulated on their own--- not to subclass class SS( Sending ): with various behaviors: that is, to assign them as class attributes rather than superclasses. You may look at the SimpleXMLRPCServer class and see how it implements introspection. It's rather easy (and doesn't require metaclasses nor decorators nor any other fancy stuff; I think it works the same since Python 2.1). Apparently you're doing a similar thing, but using pickles instead of xmlrpc. -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: Difference between 'function' and 'method'
Gabriel Genellina [EMAIL PROTECTED] wrote: En Thu, 06 Mar 2008 23:46:43 -0200, [EMAIL PROTECTED] escribi�: [ ... ] You may look at the SimpleXMLRPCServer class and see how it implements introspection. It's rather easy (and doesn't require metaclasses nor decorators nor any other fancy stuff; I think it works the same since Python 2.1). Apparently you're doing a similar thing, but using pickles instead of xmlrpc. It's not that difficult to graft pickles into SimpleXMLRPCServer -- I've done it, and if you're trying to sling large data structures over the connection it's a massive performance win (even with sgmlop in place to speed up XML parsing). -- \S -- [EMAIL PROTECTED] -- http://www.chaos.org.uk/~sion/ Frankly I have no feelings towards penguins one way or the other -- Arthur C. Clarke her nu becomeþ se bera eadward ofdun hlæddre heafdes bæce bump bump bump -- http://mail.python.org/mailman/listinfo/python-list
Re: Difference between 'function' and 'method'
On Mar 7, 6:44 am, Sion Arrowsmith [EMAIL PROTECTED] wrote: Gabriel Genellina [EMAIL PROTECTED] wrote: En Thu, 06 Mar 2008 23:46:43 -0200, [EMAIL PROTECTED] escribi�: [ ... ] You may look at the SimpleXMLRPCServer class and see how it implements introspection. It's rather easy (and doesn't require metaclasses nor decorators nor any other fancy stuff; I think it works the same since Python 2.1). Apparently you're doing a similar thing, but using pickles instead of xmlrpc. It's not that difficult to graft pickles into SimpleXMLRPCServer -- I've done it, and if you're trying to sling large data structures over the connection it's a massive performance win (even with sgmlop in place to speed up XML parsing). her nu becomeþ se bera eadward ofdun hlæddre heafdes bæce bump bump bump Yeah, but I'd be grafting a non-blocking RPC sequence too. -Instantiate- attributes of ISS upon instantiation. class C: d= D c= C() assert isinstance( c.d, D ) assert c.d is c.d Which ones? -- http://mail.python.org/mailman/listinfo/python-list
Re: Difference between 'function' and 'method'
En Wed, 05 Mar 2008 02:57:58 -0200, [EMAIL PROTECTED] escribi�:
Can you overload -type-'s decision of what to 'bind'?...
whenever it
is it makes it.
Use delegation instead of inheritance. This class is almost
indistinguishable from a true function (when used as a method):
Notwithstanding. Now bar has a name.
Now func has it.
from functools import wraps
class myfunction:
__slots__ = ('func','name')
#
def __init__(self, func):
@wraps( func )
def f( *ar, **kws ):
return func( self, *ar, **kws )
object.__setattr__(self, 'func', f)
object.__setattr__(self, 'name', None)
#
def __get__(self, instance, owner):
print( __get__ called for,instance )
return self.func.__get__(instance, owner)
#
def __getattr__(self, name):
return getattr(self.func, name)
#
def __setattr__(self, name, value):
object.__setattr__(self.func, name, value)
class mymeta( type ):
def __init__( self, name, bases, namespace ):
for k,v in namespace.items():
if isinstance( v, myfunction ):
v.name= k
class P( metaclass= mymeta ):
def foo(self, x): print( 'foo',x )
#
@myfunction
def bar( fob,self, x): print( 'bar',fob,x )
p= P()
p.foo( 0 )
p.bar( 1 )
print( p.bar )
print( p.bar.name )
Mmm, looks too complicated and I don't see any advantage over the original
code. Functions already know their (original) name: func_name. If `name`
was just an example, note that functions already have writeable attributes
too, and my code exposes them as well. This should work with that version
(untested):
p = P()
print p.bar.func_name # - bar
p.bar.im_func.anotherattribute = 1
print p.bar.anotherattribute # - 1
(the attribute must be set on the *function* itself if you want it to be
somewhat persistent; methods are usually volatile objects)
--
Gabriel Genellina
--
http://mail.python.org/mailman/listinfo/python-list
Re: Difference between 'function' and 'method'
On Mar 6, 5:35 am, Gabriel Genellina [EMAIL PROTECTED] wrote:
En Wed, 05 Mar 2008 02:57:58 -0200, [EMAIL PROTECTED] escribi�:
Can you overload -type-'s decision of what to 'bind'?...
whenever it
is it makes it.
Use delegation instead of inheritance. This class is almost
indistinguishable from a true function (when used as a method):
Notwithstanding. Now bar has a name.
Now func has it.
from functools import wraps
class myfunction:
__slots__ = ('func','name')
#
def __init__(self, func):
@wraps( func )
def f( *ar, **kws ):
return func( self, *ar, **kws )
object.__setattr__(self, 'func', f)
object.__setattr__(self, 'name', None)
#
def __get__(self, instance, owner):
print( __get__ called for,instance )
return self.func.__get__(instance, owner)
#
def __getattr__(self, name):
return getattr(self.func, name)
#
def __setattr__(self, name, value):
object.__setattr__(self.func, name, value)
class mymeta( type ):
def __init__( self, name, bases, namespace ):
for k,v in namespace.items():
if isinstance( v, myfunction ):
v.name= k
class P( metaclass= mymeta ):
def foo(self, x): print( 'foo',x )
#
@myfunction
def bar( fob,self, x): print( 'bar',fob,x )
p= P()
p.foo( 0 )
p.bar( 1 )
print( p.bar )
print( p.bar.name )
Mmm, looks too complicated and I don't see any advantage over the original
code. Functions already know their (original) name: func_name. If `name`
was just an example, note that functions already have writeable attributes
too, and my code exposes them as well. This should work with that version
(untested):
p = P()
print p.bar.func_name # - bar
p.bar.im_func.anotherattribute = 1
print p.bar.anotherattribute # - 1
(the attribute must be set on the *function* itself if you want it to be
somewhat persistent; methods are usually volatile objects)
You read my mind.
I was just getting:
assert p.bar is p.bar
and failing.
But if you set them on im_func, instances don't have their own.
--
http://mail.python.org/mailman/listinfo/python-list
Re: Difference between 'function' and 'method'
En Thu, 06 Mar 2008 22:56:33 -0200, [EMAIL PROTECTED] escribió: On Mar 6, 5:35 am, Gabriel Genellina [EMAIL PROTECTED] wrote: p = P() print p.bar.func_name # - bar p.bar.im_func.anotherattribute = 1 print p.bar.anotherattribute # - 1 (the attribute must be set on the *function* itself if you want it to be somewhat persistent; methods are usually volatile objects) You read my mind. You could try to write in a way that reading your mind isn't necesary... I was just getting: assert p.bar is p.bar and failing. But if you set them on im_func, instances don't have their own. Instances don't have their own methods either. What do you actually want to do? If you need a method with per-instance attributes, that looks like another object to me. -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: Difference between 'function' and 'method'
On Mar 6, 7:10 pm, Gabriel Genellina [EMAIL PROTECTED] wrote: En Thu, 06 Mar 2008 22:56:33 -0200, [EMAIL PROTECTED] escribió: On Mar 6, 5:35 am, Gabriel Genellina [EMAIL PROTECTED] wrote: p = P() print p.bar.func_name # - bar p.bar.im_func.anotherattribute = 1 print p.bar.anotherattribute # - 1 (the attribute must be set on the *function* itself if you want it to be somewhat persistent; methods are usually volatile objects) You read my mind. You could try to write in a way that reading your mind isn't necesary... I was just getting: assert p.bar is p.bar and failing. But if you set them on im_func, instances don't have their own. Instances don't have their own methods either. What do you actually want to do? If you need a method with per-instance attributes, that looks like another object to me. Hi, great thanks for giving me your ear this far. First of all, -I have it working-. But the design isn't encapsulated quite right. Here's what I have. 69 lines, so I'll ask to post it first. The gist is: class ISS( SS, metaclass= autonaming ): message= MessageDec() @message def user_act( msg, self, change ): print( 'user act self change', msg, self, change ) IncomingServer... but it originally came from 'clientsideserver.' iss= ISS() class OSS( SS, metaclass= autonaming ): message= MessageDec() user_act= message.out() oss= OSS() oss.message is a abstraction class that writes the method name into a string, then sends it to OSS... outgoingserver or serverside. Now that I'm writing it, and this is important, -to- the -newsgroup-, I realize you could do it with a simple wrapper... include the function name in parameters and call the pickler and send. OSS then looks like this: def something_happens( *ar ): self.user_act( something_about( *ar ) ) So the message.out() instance pickles ( 'user_act', ar ) and sends it. Then iss.incoming receives it, unpickles that string, gets 'user_act' from self, and invokes. The cool part is the declaration of user_act= message.out(), which uses a metaclass to assign its own name, and returns a function which includes the object in its signature. Cool. Yes it's working and a little slack. However-: this is the cool part. I'd like messages to know which instance they came from, and perform the sending receiving encapsulated on their own--- not to subclass class SS( Sending ): with various behaviors: that is, to assign them as class attributes rather than superclasses. The dreaming comes in here--- I'd like the class to look just like this. Tell me it's possible. And I changed my mind on posting the code, here's the whole thing. Just get SS.send and SS.incoming into MessageDec. har har har har har. Change anything before class OSS:. How does a weak reference lookup in doublebound sound? from functools import wraps import pickle class doublebound: __slots__ = ( '_func', 'assname', '_orig' ) def __init__( self, func ): @wraps( func ) def f( *ar, **kws ): return func( self, *ar, **kws ) self.assname= None self._func, self._orig= f, func def __get__( self, instance, owner ): return self._func.__get__( instance, owner ) class autonaming( type ): def __init__( self, name, bases, namespace ): for k,v in namespace.items(): if isinstance( v, doublebound ): v.assname= k class Sending: def send( *ar, **kws ): raise NotImplemented class MessageDec: def __call__( self, fun ): return doublebound( fun ) def out( self ): return doublebound( self._send ) def _send( self, message, other, *ar, **kws ): return other.send( message.assname, *ar, **kws ) class SS( Sending ): def send( self, methn, *ar, **kws ): transpmessage= methn, ar, kws transpstr= pickle.dumps( transpmessage ) self.far.incoming( transpstr ) def incoming( self, transpstr ): transpmessage= pickle.loads( transpstr ) methn, ar, kws= transpmessage meth= getattr( self, methn ) meth( *ar, **kws ) class OSS( SS, metaclass= autonaming ): message= MessageDec() user_act= message.out() somethingelse= message.out() @message def amessage( msg, self, *change ): print( 'something else', change ) class ISS( SS, metaclass= autonaming ): message= MessageDec() @message def user_act( msg, self, change ): print( 'user act self change', msg, self, change ) @message def somethingelse( msg, self, change= 'and' ):
Re: Difference between 'function' and 'method'
On 4 Mar, 09:22, 甜瓜 [EMAIL PROTECTED] wrote: This is a big problem puzzles me for a long time. The core question is: How to dynamically create methods on a class or an instance? Let me state it step by step. 1. def gunc(self): pass class A(object): def func(self): pass a = A() a.func # gives bound method, type is instancemethod A.func # gives unbound method, type is instancemethod gunc# gives function, type if function # ?? Does this line attach a method to instance? ... I don't think so. a.gunc = gunc No, unfortunately not. You might get the detailed explanation from someone else, but generally, you have to assign functions to classes; these are then exposed as methods via instances of such classes. A.gunc = gunc I found stardard library 'new' may help. Is that right? Yes, it can help: import new a.gunc = new.instancemethod(gunc, a, A) 2. a = A() # instance of old class A # Do attach a new method to class A... b = A() # instance of new class A Does a can get the new method automatically? Can a get the new method automatically? Apparently, yes: class A: pass a = A() def f(self, x): print x A.f = f a.f(123) # works, printing 123 Does new method have the *same* concept level with old methods? Especially, if there are classes inherit from class A, how does name resolution work on this case? As far as I'm aware, after you've added a method to a class, instances will regard the method like all the previously existing methods, since method lookup is a dynamic operation. I'll not address your other questions in this message since I'm not a heavy user of decorators and don't want to provide a quick answer without fully testing it first. However, it is important to remember that the magic occurs for class attributes, not instance attributes. So, for example, it's quite possible that you'd want to assign a function to an instance attribute, but you wouldn't want the instance to suddenly own that function... def somefunc(x, y): # Do something with x and y... return x + y a = A() a.somefunc = somefunc # store the function somewhere # Later... adder = a.somefunc # Later still... result = adder(p, q) # wouldn't work if somefunc became a method Python seems to do the most intuitive thing, I think, but it's quite tricky to contemplate all the implications. Paul P.S. I can never really remember all the different situations and outcomes with method assignment, but then it's something I hardly ever do. I'd be interested to know whether my situation is unusual, however. -- http://mail.python.org/mailman/listinfo/python-list
Re: Difference between 'function' and 'method'
?? a écrit :
Howdy everyone,
This is a big problem puzzles me for a long time. The core question is:
How to dynamically create methods on a class or an instance?
class Foo(object):
pass
def bar(self, arg):
print in bar : self == % - arg == %s % (self, str(arg))
def baaz(self, arg):
print in baaz : self == % - arg == %s % (self, str(arg))
f = Foo()
# adding bar as a method to class Foo
Foo.bar = bar
# f now can use bar:
f.bar(42)
# as well as new instances of Foo, of course
g = Foo()
g.bar()
# adding baaz as a method to f, the old way:
import new
f.baaz = new.instancemethod(baaz, f, type(f))
f.baaz()
# adding baaz as a method to g, the other way:
g.baaz = baaz.__get__(g, type(g))
g.baaz()
Let me state it step by step.
1.
def gunc(self):
pass
class A(object):
def func(self):
pass
a = A()
a.func # gives bound method, type is instancemethod
A.func # gives unbound method, type is instancemethod
gunc# gives function, type if function
# ?? Does this line attach a method to instance? ... I don't think so.
a.gunc = gunc
It doesn't.
I found stardard library 'new' may help. Is that right?
cf above. If you work with old-style classes, you'll need
new.instancemethod.
2.
a = A() # instance of old class A
# Do attach a new method to class A...
b = A() # instance of new class A
Does a can get the new method automatically?
Yes. In Python, a class is itself an object, and is an attribute of it's
instances (instance.__class__). Names are resolved at runtime, and
attributes not found in the instance's __dict__ are looked up in the
class (and then in the superclasses etc).
Does new method have the *same* concept level with old methods?
The newly added method works exactly the same way as already existing
ones. Not a single difference. The class statement is just syntactic
sugar anyway. The following snippets are equivalent:
# sugar-coated:
class Boo(object):
faaz = 0
def far(self):
type(self).faaz += 1
print self
def frob(self):
print yadda
# raw:
def far(self):
type(self).faaz += 1
print self
Boo = type('Boo', (object,), dict(faaz=0, far=far))
def frob(self):
print yadda
Boo.frob = frob
Especially, if there
are classes inherit from class A, how does name resolution work on this case?
As usual.
3.
How do I write a decroator for a method?
Mostly the same way you'd write a decorator for a function
Eg:
class A(object):
@my_dec
def func(self):
pass
Here, my_dec should return a method rathar than a function/lambda. Am I right?
Nope. Functions defined within a class statement are plain ordinary
functions. It's the lookup mechanism that turns them into methods when
they are looked up as attribute of a class. In fact, Python methods
are thin callable wrappers around a function, a class and (most of the
time) an instance, wrappers which are created - usually at lookup time -
by the __get__ method of the function type (you may want to read about
the descriptor protocol on python.org - in the section about new style
classes IIRC).
Anyway, you can explore this by yourself:
Boo.far
unbound method Boo.far
b.far
bound method Boo.far of __main__.Boo object at 0xb787f96c
Boo.__dict__['far']
function far at 0xb7c28aac
Boo.__dict__['far'] is far
True
f1 = b.far
f2 = b.far
f1 is f2
False
f1()
__main__.Boo object at 0xb787f96c
f2()
__main__.Boo object at 0xb787f96c
dir(f1)
['__call__', '__class__', '__cmp__', '__delattr__', '__doc__',
'__get__', '__getattribute__', '__hash__', '__init__', '__new__',
'__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__str__',
'im_class', 'im_func', 'im_self']
f1.im_class
class '__main__.Boo'
f1.im_func
function far at 0xb7c28aac
f1.im_func is far
True
f1.im_self
__main__.Boo object at 0xb787f96c
f1.im_self is b
True
bf = Boo.far
bf.im_func
function far at 0xb7c28aac
bf.im_func is far
True
bf.im_class
class '__main__.Boo'
bf.im_self
bf.im_self is None
True
far.__get__(b, Boo)
bound method Boo.far of __main__.Boo object at 0xb787f96c
far.__get__(b, Boo).im_func is far
True
So, to answer your question: what you are decorating are functions, not
methods.
What does @property @staticmethod... really do? I cannot step-into them for
source code.
staticmethod wraps the function into an object that, when looked up as
an attribute, will return the raw function instead of returning a method.
property is a type that provides a simple generic implementation for
computed attributes. You'll find more detailed explanations in the doc
(but perhaps not in the most obvious place - it's somewhere in the peps
or in the 'nws style classes' stuff IIRC). Anyway, using it as a
decorator is a somewhat special case (well... to me at least), that will
defined a property with only a getter (the decorated function).
4.
If most of above questions can be solved, then it
Re: Difference between 'function' and 'method'
On Mar 4, 5:27 am, Bruno Desthuilliers bruno.
[EMAIL PROTECTED] wrote:
?? a écrit :
Howdy everyone,
This is a big problem puzzles me for a long time. The core question is:
How to dynamically create methods on a class or an instance?
class Foo(object):
pass
def bar(self, arg):
print in bar : self == % - arg == %s % (self, str(arg))
def baaz(self, arg):
print in baaz : self == % - arg == %s % (self, str(arg))
f = Foo()
# adding bar as a method to class Foo
Foo.bar = bar
# f now can use bar:
f.bar(42)
# as well as new instances of Foo, of course
g = Foo()
g.bar()
# adding baaz as a method to f, the old way:
import new
f.baaz = new.instancemethod(baaz, f, type(f))
f.baaz()
# adding baaz as a method to g, the other way:
g.baaz = baaz.__get__(g, type(g))
g.baaz()
Let me state it step by step.
1.
def gunc(self):
pass
class A(object):
def func(self):
pass
a = A()
a.func # gives bound method, type is instancemethod
A.func # gives unbound method, type is instancemethod
gunc # gives function, type if function
# ?? Does this line attach a method to instance? ... I don't think so.
a.gunc = gunc
It doesn't.
I found stardard library 'new' may help. Is that right?
cf above. If you work with old-style classes, you'll need
new.instancemethod.
2.
a = A() # instance of old class A
# Do attach a new method to class A...
b = A() # instance of new class A
Does a can get the new method automatically?
Yes. In Python, a class is itself an object, and is an attribute of it's
instances (instance.__class__). Names are resolved at runtime, and
attributes not found in the instance's __dict__ are looked up in the
class (and then in the superclasses etc).
Does new method have the *same* concept level with old methods?
The newly added method works exactly the same way as already existing
ones. Not a single difference. The class statement is just syntactic
sugar anyway. The following snippets are equivalent:
# sugar-coated:
class Boo(object):
faaz = 0
def far(self):
type(self).faaz += 1
print self
def frob(self):
print yadda
# raw:
def far(self):
type(self).faaz += 1
print self
Boo = type('Boo', (object,), dict(faaz=0, far=far))
def frob(self):
print yadda
Boo.frob = frob
Especially, if there
are classes inherit from class A, how does name resolution work on this
case?
As usual.
3.
How do I write a decroator for a method?
Mostly the same way you'd write a decorator for a function
Eg:
class A(object):
@my_dec
def func(self):
pass
Here, my_dec should return a method rathar than a function/lambda. Am I
right?
Nope. Functions defined within a class statement are plain ordinary
functions. It's the lookup mechanism that turns them into methods when
they are looked up as attribute of a class. In fact, Python methods
are thin callable wrappers around a function, a class and (most of the
time) an instance, wrappers which are created - usually at lookup time -
by the __get__ method of the function type (you may want to read about
the descriptor protocol on python.org - in the section about new style
classes IIRC).
Anyway, you can explore this by yourself:
Boo.far
unbound method Boo.far
b.far
bound method Boo.far of __main__.Boo object at 0xb787f96c
Boo.__dict__['far']
function far at 0xb7c28aac
Boo.__dict__['far'] is far
True
f1 = b.far
f2 = b.far
f1 is f2
False
f1()
__main__.Boo object at 0xb787f96c
f2()
__main__.Boo object at 0xb787f96c
dir(f1)
['__call__', '__class__', '__cmp__', '__delattr__', '__doc__',
'__get__', '__getattribute__', '__hash__', '__init__', '__new__',
'__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__str__',
'im_class', 'im_func', 'im_self']
f1.im_class
class '__main__.Boo'
f1.im_func
function far at 0xb7c28aac
f1.im_func is far
True
f1.im_self
__main__.Boo object at 0xb787f96c
f1.im_self is b
True
bf = Boo.far
bf.im_func
function far at 0xb7c28aac
bf.im_func is far
True
bf.im_class
class '__main__.Boo'
bf.im_self
bf.im_self is None
True
far.__get__(b, Boo)
bound method Boo.far of __main__.Boo object at 0xb787f96c
far.__get__(b, Boo).im_func is far
True
So, to answer your question: what you are decorating are functions, not
methods.
Can you overload -type-'s decision of what to 'bind'?... whenever it
is it makes it.
--
http://mail.python.org/mailman/listinfo/python-list
Re: Difference between 'function' and 'method'
So, to answer your question: what you are decorating are functions, not methods. Can you overload -type-'s decision of what to 'bind'?... whenever it is it makes it. from types import FunctionType, MethodType class A( FunctionType ): pass ... Traceback (most recent call last): File stdin, line 1, in module TypeError: type 'function' is not an acceptable base type class A( MethodType ): pass ... Traceback (most recent call last): File stdin, line 1, in module TypeError: type 'method' is not an acceptable base type Unacceptable. -- http://mail.python.org/mailman/listinfo/python-list
Re: Difference between 'function' and 'method'
En Tue, 04 Mar 2008 16:45:40 -0200, [EMAIL PROTECTED] escribió:
So, to answer your question: what you are decorating are functions,
not
methods.
Can you overload -type-'s decision of what to 'bind'?... whenever it
is it makes it.
from types import FunctionType, MethodType
class A( FunctionType ): pass
...
Traceback (most recent call last):
File stdin, line 1, in module
TypeError: type 'function' is not an acceptable base type
Use delegation instead of inheritance. This class is almost
indistinguishable from a true function (when used as a method):
py class myfunction(object):
... __slots__ = ('func',)
... #
... def __init__(self, func):
... object.__setattr__(self, 'func', func)
... #
... def __get__(self, instance, owner):
... print __get__ called for,instance
... return self.func.__get__(instance, owner)
... #
... def __getattr__(self, name):
... return getattr(self.func, name)
... #
... def __setattr__(self, name, value):
... object.__setattr__(self.func, name, value)
...
py
py class P(object):
... def foo(self, x): print 'foo',x
... #
... @myfunction
... def bar(self, x): print 'bar',x
...
py p = P()
py p.foo(1)
foo 1
py p.bar(2)
__get__ called for __main__.P object at 0x00A3D650
bar 2
py P.foo(p, 1)
foo 1
py P.bar(p, 2)
__get__ called for None
bar 2
py print p.foo, p.foo, type(p.foo)
p.foo bound method P.foo of __main__.P object at 0x00A3D650 type
'instancem
ethod'
py print p.bar, p.bar, type(p.bar)
p.bar __get__ called for __main__.P object at 0x00A3D650
bound method P.bar of __main__.P object at 0x00A3D650 __get__ called
for __
main__.P object at 0x00A3D650
type 'instancemethod'
py print set(dir(p.foo))==set(dir(p.bar))
__get__ called for __main__.P object at 0x00A3D650
True
py print P.foo, P.foo, type(P.foo)
P.foo unbound method P.foo type 'instancemethod'
py print P.bar, P.bar, type(P.bar)
P.bar __get__ called for None
unbound method P.bar __get__ called for None
type 'instancemethod'
py print set(dir(P.foo))==set(dir(P.bar))
__get__ called for None
True
py P.__dict__['foo']
function foo at 0x00A3BCB0
py P.__dict__['bar']
__main__.myfunction object at 0x00A3D690
Ok, let's try returning a different thing from __get__: bound method -
partial with self already bound; unbound method - the original function.
py from functools import partial
py
py class myfunction2(myfunction):
... def __get__(self, instance, owner):
... if instance is None:
... return self.func
... return partial(self.func, instance)
...
py @myfunction2
... def baz(self, x): print 'baz',x
...
py P.baz = baz
py print p.baz
functools.partial object at 0x00A3E5A0
py print P.baz
function baz at 0x00AB1030
py p.baz(3)
baz 3
py P.baz(p,3)
baz 3
--
Gabriel Genellina
--
http://mail.python.org/mailman/listinfo/python-list
Re: Difference between 'function' and 'method'
On Mar 4, 8:11 pm, Gabriel Genellina [EMAIL PROTECTED] wrote:
En Tue, 04 Mar 2008 16:45:40 -0200, [EMAIL PROTECTED] escribió:
So, to answer your question: what you are decorating are functions,
not
methods.
Can you overload -type-'s decision of what to 'bind'?... whenever it
is it makes it.
from types import FunctionType, MethodType
class A( FunctionType ): pass
...
Traceback (most recent call last):
File stdin, line 1, in module
TypeError: type 'function' is not an acceptable base type
Use delegation instead of inheritance. This class is almost
indistinguishable from a true function (when used as a method):
py class myfunction(object):
... __slots__ = ('func',)
... #
... def __init__(self, func):
... object.__setattr__(self, 'func', func)
... #
... def __get__(self, instance, owner):
... print __get__ called for,instance
... return self.func.__get__(instance, owner)
... #
... def __getattr__(self, name):
... return getattr(self.func, name)
... #
... def __setattr__(self, name, value):
... object.__setattr__(self.func, name, value)
...
py
py class P(object):
... def foo(self, x): print 'foo',x
... #
... @myfunction
... def bar(self, x): print 'bar',x
...
py p = P()
py p.foo(1)
foo 1
py p.bar(2)
__get__ called for __main__.P object at 0x00A3D650
bar 2
py P.foo(p, 1)
foo 1
py P.bar(p, 2)
__get__ called for None
bar 2
py print p.foo, p.foo, type(p.foo)
p.foo bound method P.foo of __main__.P object at 0x00A3D650 type
'instancem
ethod'
py print p.bar, p.bar, type(p.bar)
p.bar __get__ called for __main__.P object at 0x00A3D650
bound method P.bar of __main__.P object at 0x00A3D650 __get__ called
for __
main__.P object at 0x00A3D650
type 'instancemethod'
py print set(dir(p.foo))==set(dir(p.bar))
__get__ called for __main__.P object at 0x00A3D650
True
py print P.foo, P.foo, type(P.foo)
P.foo unbound method P.foo type 'instancemethod'
py print P.bar, P.bar, type(P.bar)
P.bar __get__ called for None
unbound method P.bar __get__ called for None
type 'instancemethod'
py print set(dir(P.foo))==set(dir(P.bar))
__get__ called for None
True
py P.__dict__['foo']
function foo at 0x00A3BCB0
py P.__dict__['bar']
__main__.myfunction object at 0x00A3D690
Ok, let's try returning a different thing from __get__: bound method -
partial with self already bound; unbound method - the original function.
py from functools import partial
py
py class myfunction2(myfunction):
... def __get__(self, instance, owner):
... if instance is None:
... return self.func
... return partial(self.func, instance)
...
py @myfunction2
... def baz(self, x): print 'baz',x
...
py P.baz = baz
py print p.baz
functools.partial object at 0x00A3E5A0
py print P.baz
function baz at 0x00AB1030
py p.baz(3)
baz 3
py P.baz(p,3)
baz 3
--
Gabriel Genellina
I actually don't believe you-- bar is not bound to an instance when P
is initialized... er, instantiated. However, the evidence indicates
my belief mechanism is faulty... and rather conclusively at that.
moves to acquire new evidence If P calls __get__( you ), is p a
gotcha?
--
http://mail.python.org/mailman/listinfo/python-list
Re: Difference between 'function' and 'method'
En Wed, 05 Mar 2008 00:30:26 -0200, [EMAIL PROTECTED] escribió: On Mar 4, 8:11 pm, Gabriel Genellina [EMAIL PROTECTED] wrote: En Tue, 04 Mar 2008 16:45:40 -0200, [EMAIL PROTECTED] escribió: Can you overload -type-'s decision of what to 'bind'?... whenever it is it makes it. from types import FunctionType, MethodType class A( FunctionType ): pass ... Traceback (most recent call last): File stdin, line 1, in module TypeError: type 'function' is not an acceptable base type Use delegation instead of inheritance. This class is almost indistinguishable from a true function (when used as a method): [... long interactive example ...] I actually don't believe you-- bar is not bound to an instance when P is initialized... er, instantiated. However, the evidence indicates my belief mechanism is faulty... and rather conclusively at that. moves to acquire new evidence If P calls __get__( you ), is p a gotcha? I didn't cheat, that was an actual Python interactive session. So you'll have to formulate a new theory taking into account the new facts... or read how the descriptor protocol works http://www.python.org/doc/newstyle/ I don't understand your last sentence. -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: Difference between 'function' and 'method'
On Mar 4, 9:01 pm, Gabriel Genellina [EMAIL PROTECTED] wrote: En Wed, 05 Mar 2008 00:30:26 -0200, [EMAIL PROTECTED] escribió: On Mar 4, 8:11 pm, Gabriel Genellina [EMAIL PROTECTED] wrote: En Tue, 04 Mar 2008 16:45:40 -0200, [EMAIL PROTECTED] escribió: Can you overload -type-'s decision of what to 'bind'?... whenever it is it makes it. from types import FunctionType, MethodType class A( FunctionType ): pass ... Traceback (most recent call last): File stdin, line 1, in module TypeError: type 'function' is not an acceptable base type Use delegation instead of inheritance. This class is almost indistinguishable from a true function (when used as a method): [... long interactive example ...] I actually don't believe you-- bar is not bound to an instance when P is initialized... er, instantiated. However, the evidence indicates my belief mechanism is faulty... and rather conclusively at that. moves to acquire new evidence If P calls __get__( you ), is p a gotcha? I didn't cheat, that was an actual Python interactive session. So you'll have to formulate a new theory taking into account the new facts... or read how the descriptor protocol workshttp://www.python.org/doc/newstyle/ I don't understand your last sentence. -- Gabriel Genellina joke If P gets, p gotcha. /joke gotcha= partial( get, you ). bor hor hor. Yes... regarding the descriptoring, just make it official! UserFunctionType or smg. -- http://mail.python.org/mailman/listinfo/python-list
Re: Difference between 'function' and 'method'
On Mar 4, 9:53 pm, [EMAIL PROTECTED] wrote:
Can you overload -type-'s decision of what to 'bind'?... whenever it
is it makes it.
from types import FunctionType, MethodType
class A( FunctionType ): pass
...
Traceback (most recent call last):
File stdin, line 1, in module
TypeError: type 'function' is not an acceptable base type
Use delegation instead of inheritance. This class is almost
indistinguishable from a true function (when used as a method):
If P gets, p gotcha.
/joke
gotcha= partial( get, you ). bor hor hor. Yes...
Notwithstanding. Now bar has a name.
class myfunction:
__slots__ = ('func','name')
#
def __init__(self, func):
object.__setattr__(self, 'func', func)
object.__setattr__(self, 'name', None)
#
def __get__(self, instance, owner):
print( __get__ called for,instance )
return self.func.__get__(instance, owner)
#
def __getattr__(self, name):
return getattr(self.func, name)
#
def __setattr__(self, name, value):
object.__setattr__(self.func, name, value)
class mymeta( type ):
def __init__( self, name, bases, namespace ):
for k,v in namespace.items():
if isinstance( v, myfunction ):
v.name= k
class P( metaclass= mymeta ):
def foo(self, x): print( 'foo',x )
#
@myfunction
def bar(self, x): print( 'bar',x )
p= P()
p.foo( 0 )
p.bar( 1 )
print( p.bar )
print( p.bar.name )
'''
output:
'''
foo 0
__get__ called for __main__.P object at 0x00B481F0
bar 1
__get__ called for __main__.P object at 0x00B481F0
bound method P.bar of __main__.P object at 0x00B481F0
__get__ called for __main__.P object at 0x00B481F0
bar
--
http://mail.python.org/mailman/listinfo/python-list
Re: Difference between 'function' and 'method'
Can you overload -type-'s decision of what to 'bind'?... whenever it
is it makes it.
from types import FunctionType, MethodType
class A( FunctionType ): pass
...
Traceback (most recent call last):
File stdin, line 1, in module
TypeError: type 'function' is not an acceptable base type
Use delegation instead of inheritance. This class is almost
indistinguishable from a true function (when used as a method):
If P gets, p gotcha.
/joke
gotcha= partial( get, you ). bor hor hor. Yes...
Notwithstanding. Now bar has a name.
Now func has it.
from functools import wraps
class myfunction:
__slots__ = ('func','name')
#
def __init__(self, func):
@wraps( func )
def f( *ar, **kws ):
return func( self, *ar, **kws )
object.__setattr__(self, 'func', f)
object.__setattr__(self, 'name', None)
#
def __get__(self, instance, owner):
print( __get__ called for,instance )
return self.func.__get__(instance, owner)
#
def __getattr__(self, name):
return getattr(self.func, name)
#
def __setattr__(self, name, value):
object.__setattr__(self.func, name, value)
class mymeta( type ):
def __init__( self, name, bases, namespace ):
for k,v in namespace.items():
if isinstance( v, myfunction ):
v.name= k
class P( metaclass= mymeta ):
def foo(self, x): print( 'foo',x )
#
@myfunction
def bar( fob,self, x): print( 'bar',fob,x )
p= P()
p.foo( 0 )
p.bar( 1 )
print( p.bar )
print( p.bar.name )
--
http://mail.python.org/mailman/listinfo/python-list
Re: Difference between 'function' and 'method'
On Mar 4, 10:57 pm, [EMAIL PROTECTED] wrote:
Can you overload -type-'s decision of what to 'bind'?... whenever
it
is it makes it.
from types import FunctionType, MethodType
class A( FunctionType ): pass
...
Traceback (most recent call last):
File stdin, line 1, in module
TypeError: type 'function' is not an acceptable base type
Use delegation instead of inheritance. This class is almost
indistinguishable from a true function (when used as a method):
If P gets, p gotcha.
Notwithstanding. Now bar has a name.
Now func has it.
from functools import wraps
class myfunction:
__slots__ = ('func','name')
#
def __init__(self, func):
@wraps( func )
def f( *ar, **kws ):
return func( self, *ar, **kws )
object.__setattr__(self, 'func', f)
object.__setattr__(self, 'name', None)
Now:
Where is partialobject.__get__, why is 'attribute __get__ read-
only', and for self.__get__= func.__get__, why is 'member_descriptor'
object is not callable?
--
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