Trying to generate a list of the subclasses of C

[Charles Krug]

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:

True

but

issubclass(classC.__dict__['D'], C)

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'(), '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.

 

[Diez B. Roggisch]

The end result I'm after is an automatically generated dictionary

containing instaces of the subclasses keyed by the subclass names:

{'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.

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

 

[Pierre Barbier de Reuille]

Charles Krug a écrit :

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

Where is C defined ?

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

Which gives me this:

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

However when I do this from the command line:

issubclass(D,C)

True

but

issubclass(classC.__dict__['D'], C)

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'(), '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.

 

[Duncan Booth]

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

{'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.

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()

 

[Alex Martelli]

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

There's a class method for that very purpose:


Alex

 

[Charles Krug]

There's a class method for that very purpose:



Alex

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.