I have a couple of {{{TypedDict}}}s for use in type hinting that are supposed 
to have some sets of incompatible keys.

For example, if I need to specify that a particular {{{dict}}} can have 
{{{bar}}} or {{{baz}}} but not both of them, I can write two {{{TypedDict}}}s:

{{{#!highlight python
from typing import TypedDict

class Foo1(TypedDict):
  bar: str
    
class Foo2(TypedDict):
  baz: int

Foo = Foo1 | Foo2

foo_instance_1: Foo = {  # Works fine
  'bar': 'foobar'
}
foo_instance_2: Foo = {  # Also fine
  'baz': 42
}

foo_instance_3: Foo = {  # Warning: Expected type 'Foo1 | Foo2', got 'dict[str, 
str | int]' instead
  'bar': 'foobar',
  'baz': 42
}
}}}

However, this doesn't scale very well if I were to have multiple sets; for 
example, a simple multiplication shows that three sets of 2, 3 and 4 keys each 
will result in 24 {{{TypedDict}}}s. A solution would be:

{{{#!highlight python
class Foo(TypedDict):
  bar: IncompatibleWith('baz', 'qux')[str]
  baz: IncompatibleWith('bar', 'qux')[int]
  qux: IncompatibleWith('bar', 'baz')[bool]
}}}

...or, with a decorator somewhat similar to {{{@overload}}}:

{{{#!highlight python
@incompatible('bar', 'baz', 'qux')
# ...
class Foo(TypedDict):
  bar: str
  baz: int
  qux: bool
}}}

I asked this question on StackOverflow<https://stackoverflow.com/q/75981727> 
and was informed that such a feature doesn't exist. How about adding it to 
Python then?
_______________________________________________
Python-ideas mailing list -- python-ideas@python.org
To unsubscribe send an email to python-ideas-le...@python.org
https://mail.python.org/mailman3/lists/python-ideas.python.org/
Message archived at 
https://mail.python.org/archives/list/python-ideas@python.org/message/TPILQMOHCWAD7GKDCREONOHZTFY5Z7YW/
Code of Conduct: http://python.org/psf/codeofconduct/

Reply via email to