In the following example, the list1 attribute of P represents a list of instances of A.
class A:
value1: str
class B(A):
value2: str
class P:
list1: List[A]
I want is to keep a list of child classes of A (not instances of A) in the variable list1. Is there a way to do it in python?
The solution is to use https://docs.python.org/3/library/typing.html#typing.Type.
from typing import List, Type
class P:
list1: List[Type[A]]
Now, list1 represents a list of classes extended from A.
my try copying from first answer here :How to find all the subclasses of a class given its name? :
class klass():
pass
class popo(klass):
pass
class pepe(klass):
pass
class P():
def get_all_subclasses(self, cls):
subclass_list = []
def recurse(classe):
for subclass in classe.__subclasses__():
subclass_list.append(subclass)
recurse(subclass)
recurse(cls)
return list(set(subclass_list))
a = P()
print(a.get_all_subclasses(klass),'\n')
print(type(a.get_all_subclasses(klass)),'\n')
class papa(klass):
pass
class coco(popo):
pass
print(a.get_all_subclasses(klass),'\n')
output:
[<class '__main__.popo'>, <class '__main__.pepe'>]
<class 'list'>
[<class '__main__.papa'>, <class '__main__.popo'>, <class '__main__.pepe'>, <class '__main__.coco'>]
or :
class klass:
pass
class popo(klass):
pass
class pepe(klass):
pass
class P:
def __init__(self, classez):
self.list1 = []
self.get_all_subclasses(classez)
pass
def get_all_subclasses(self, cls):
def recurse(classe):
for subclass in classe.__subclasses__():
self.list1.append(subclass)
recurse(subclass) # necessarioo per avere coco nella lista
recurse(cls)
self.list1 = list((self.list1))
return self.list1
a = P(klass)
print(a.list1, "\n")
print(type(a.list1), "\n")
class papa(klass):
pass
class coco(popo):
pass
a = P(klass)
print(a.list1)
I get too:
[<class '__main__.popo'>, <class '__main__.pepe'>]
<class 'list'>
[<class '__main__.popo'>, <class '__main__.coco'>, <class '__main__.pepe'>, <class '__main__.papa'>]
using :
class klass():
pass
class popo(klass):
pass
class pepe(klass):
pass
print(klass.__subclasses__(),'\n')
class papa(klass):
pass
class coco(popo):
pass
print(klass.__subclasses__(),'\n')
I get:
[<class '__main__.popo'>, <class '__main__.pepe'>]
[<class '__main__.popo'>, <class '__main__.pepe'>, <class '__main__.papa'>]
...
class P:
A.__subclasses__()
>>> [<class '__main__.B'>, <class '__main__.C'>, <class '__main__.D'>]
subclasses - Returns a list of weak references to classes directly inherited from this one. enter link description here
