Specifying __slots__ in a dynamically generated type
Leif K-Brooks
eurleif at ecritters.biz
Sun Mar 27 18:33:43 EST 2005
Ron Garret wrote:
> I need to dynamically generate new types at run time. I can do this in
> two ways. I can use the "type" constructor, or I can generate a "class"
> statement as a string and feed that to the exec function. The former
> technique is much cleaner all else being equal, but I want to be able to
> specify the __slots__ class variable for these new types, and it seems
> that to do that I need to use the latter method. Is that true? Is it
> really impossible to specify __slots__ using the "type" constructor?
Using __slots__ with type() works for me:
Python 2.3.5 (#2, Feb 9 2005, 00:38:15)
[GCC 3.3.5 (Debian 1:3.3.5-8)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> FooClass = type('foo', (object, ), {'__slots__': 'foo'})
>>> foo = FooClass()
>>> foo.bar = 1
Traceback (most recent call last):
File "<stdin>", line 1, in ?
AttributeError: 'foo' object has no attribute 'bar'
>>> foo.foo = 2
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