Add 'factory' support for the Any trait type #1557
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Looking into the stubs-related test failure ... |
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I think the mypy complaint is legitimate here. I've updated the test accordingly. |
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Whoops; the user manual does need updating here. Now done. |
| @@ -278,7 +278,9 @@ the table. | |||
| +------------------+----------------------------------------------------------+ | |||
| | Name | Callable Signature | | |||
| +==================+==========================================================+ | |||
| | Any | Any( [*value* = None, \*\*\ *metadata*] ) | | |||
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Corrected the name of the initial parameter from value to default_value (though I expect few people will be passing that parameter by name).
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| class Subclass(Superclass): | ||
| x = Instance(Foo) | ||
| x = Instance(Foo) # E: assignment |
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This line didn't raise before this PR, and does now; I believe that this was a bug in the test. mypy infers from Superclass that the attribute x should have type Any, and complains about the non-matching assignment in the subclass, which seems like a legitimate complaint.
| *, | ||
| factory=None, | ||
| args=(), | ||
| kw={}, |
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Yes, this is considered an antipattern (compared to using kw=None and then explicitly checking for None in the body of the function). No, I don't want to change it unless people feel really strongly about it. A default of {} makes the code, documentation and typing stubs simpler and clearer, and the usual concern about mutable default values doesn't apply here, because there's no plausible way that accidental mutation of this default value could take place.
Co-authored-by: Poruri Sai Rahul <rporuri@enthought.com>
This PR adds
factory,argsandkwkeyword-only arguments to theAnytrait type initializer, allowing a default value for anAnytrait to be specified via a factory, in much the same way as this already works for theInstancetrait type.The main goal is to provide a clean migration path for existing code using
Any({})orAny([]). With Traits 6.3, such code will run into the deprecation introduced in #1532, and can now useAny(factory=dict)orAny(factory=list)as a suitable replacement that won't warn.Checklist
docs/source/traits_api_reference)docs/source/traits_user_manual)traits-stubs