List:

I have this:

# classC.py

class C(object): pass

class D(C): pass

class E(C): pass

def CSubclasses():
for name in dir(): pass

I'm trying to create a list of all of C's subclasses:

import classC

print C
aList = []
for name in dir(classC):
print name,
try:
if issubclass(classC.__dict__[name], C):
print classC.__dict__[name]
else:
print
except TypeError:
print

Which gives me this:

<class '__main__.C'>
C
CSubclasses
D
E
__builtins__
__doc__
__file__
__name__

However when I do this from the command line:
[color=blue][color=green][color=darkred]
>>> issubclass(D,C)[/color][/color][/color]
True

but
[color=blue][color=green][color=darkred]
>>> issubclass(classC.__dict__['D'], C)[/color][/color][/color]
False

So my approach is flawed.

The end result I'm after is an automatically generated dictionary
containing instaces of the subclasses keyed by the subclass names:

{'D':D(), 'E':E(), . . . }

I can see the information I need in the module's __dict__ and by using
the dir() method, but I'm not having much success extracting it.

> The end result I'm after is an automatically generated dictionary[color=blue]
> containing instaces of the subclasses keyed by the subclass names:
>
> {'D':D(), 'E':E(), . . . }
>
> I can see the information I need in the module's __dict__ and by using
> the dir() method, but I'm not having much success extracting it.[/color]

Use a metaclass:


subclassesofc = []

class SubclassCollector(type):

def __new__(cls, name, bases, dict):
subclassesofc.append(name)
return type.__new__(cls, name, bases, dict)

class C(object):
__metaclass__ = SubclassCollector



class A(C):
pass

print subclassesofc



Regards,

Diez

Charles Krug a écrit :[color=blue]
> List:
>
> I have this:
>
> # classC.py
>
> class C(object): pass
>
> class D(C): pass
>
> class E(C): pass
>
> def CSubclasses():
> for name in dir(): pass
>
> I'm trying to create a list of all of C's subclasses:
>
> import classC
>
> print C
> aList = []
> for name in dir(classC):
> print name,
> try:
> if issubclass(classC.__dict__[name], C):
> print classC.__dict__[name]
> else:
> print
> except TypeError:
> print
>[/color]

Where is C defined ?
[color=blue][color=green][color=darkred]
>>> import classC[/color][/color][/color]

does not define the name C in the current scope ... thus, you should write :

for name in dir(classC):
print name,
try:
if issubclass(classC.__dict__[name], classC.C):
print classC.__dict__[name]
else:
print
except TypeError:
print

and it gives :

C <class 'test_subclass.C'>
CSubclasses
D <class 'test_subclass.D'>
E <class 'test_subclass.E'>
__builtins__
__doc__
__file__
__name__

.... which is exactly what you want !

Pierre
[color=blue]
> Which gives me this:
>
> <class '__main__.C'>
> C
> CSubclasses
> D
> E
> __builtins__
> __doc__
> __file__
> __name__
>
> However when I do this from the command line:
>
>[color=green][color=darkred]
>>>>issubclass(D,C)[/color][/color]
>
> True
>
> but
>
>[color=green][color=darkred]
>>>>issubclass(classC.__dict__['D'], C)[/color][/color]
>
> False
>
> So my approach is flawed.
>
> The end result I'm after is an automatically generated dictionary
> containing instaces of the subclasses keyed by the subclass names:
>
> {'D':D(), 'E':E(), . . . }
>
> I can see the information I need in the module's __dict__ and by using
> the dir() method, but I'm not having much success extracting it.
>
>
>[/color]

Charles Krug wrote:
[color=blue]
> The end result I'm after is an automatically generated dictionary
> containing instaces of the subclasses keyed by the subclass names:
>
> {'D':D(), 'E':E(), . . . }
>
> I can see the information I need in the module's __dict__ and by using
> the dir() method, but I'm not having much success extracting it.[/color]

Try this:

class C(object): pass

class D(C): pass

class E(C): pass

def CSubclasses():
return dict((cls.__name__, cls) for cls in C.__subclasses__())

print CSubclasses()

Charles Krug <cdkrug@aol.com> wrote:
...[color=blue]
> I'm trying to create a list of all of C's subclasses:[/color]

There's a class method for that very purpose:
[color=blue][color=green][color=darkred]
>>> class C(object): pass[/color][/color][/color]
....[color=blue][color=green][color=darkred]
>>> class D(C): pass[/color][/color][/color]
....[color=blue][color=green][color=darkred]
>>> class E(C): pass[/color][/color][/color]
....[color=blue][color=green][color=darkred]
>>> C.__subclasses__()[/color][/color][/color]
[<class '__main__.D'>, <class '__main__.E'>][color=blue][color=green][color=darkred]
>>>[/color][/color][/color]


Alex

On 2006-01-16, Alex Martelli <aleax@mail.comcast.net> wrote:[color=blue]
> Charles Krug <cdkrug@aol.com> wrote:
> ...[color=green]
>> I'm trying to create a list of all of C's subclasses:[/color]
>
> There's a class method for that very purpose:
>[color=green][color=darkred]
>>>> class C(object): pass[/color][/color]
> ...[color=green][color=darkred]
>>>> class D(C): pass[/color][/color]
> ...[color=green][color=darkred]
>>>> class E(C): pass[/color][/color]
> ...[color=green][color=darkred]
>>>> C.__subclasses__()[/color][/color]
> [<class '__main__.D'>, <class '__main__.E'>][color=green][color=darkred]
>>>>[/color][/color]
>
>
> Alex[/color]

Exactly what I was looking for, thanks.

It stuck in my brain that there was a way to do this, but I couldn't lay
my mouse on it.