On 2019-03-04 18:02, Jimmy Girardet wrote:
Hello,
I'm looking for an explanation where live classes created by
types.new_class() :
py> import types
py> types.new_class('A')
types.A
py> types.A
AttributeError: module 'types' has no attribute 'A'
py> _.__module__
'types'
The new class comes from `types` module without being inside.
That's annoying to me for my use case :
I'm trying to create dataclasses on the fly using make_dataclass (which
uses types.new_class). For new created classes, I have a cache to not
recreate twice the same class.
But I want to be sure not to override an existing class somewhere in the
namespace which is already 'types.MyNewclass'. but how to check it if
it's not in types ?
To be clear :
make_dataclass('Bla', {}) should raise an error if something named
'types.Bla' already exists.
I hope I'm clear enough.
'new_class' creates a new class with the given name and returns a
reference to it.
The class doesn't 'live' anywhere.
Although you might /think/ that an object lives in a certain namespace,
it's just that there's a name there that's bound to the object.
You can, in fact, create 2 classes with the same name.
>>> import types
>>> t1 = types.new_class('A')
>>> t2 = types.new_class('A')
>>> t1 is t2
False
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