mypy prints out types in inconsistent formats depending context #1582

Activity

1. JukkaL

   added

   needs discussion

   on May 26, 2016
2. JukkaL commented on May 26, 2016

   

   JukkaL

   on May 26, 2016

   Collaborator

   More actions

   Yeah, printing types is currently messy and it would be nice to clean it up. PEP 484 doesn't allow printing out all the information about types, such as *args in callable types, so we may still decide to continue having some non-standard forms.

   It may still be nice to have at least two different modes:

   1. Show a type.
   2. Show the difference between two types. We'd fall back to showing both types, but in some cases it can be useful to highlight how the two (complex) types are different/incompatible. A simple implementation would just align the types on top of each other so that the difference is easy to spot.
3. ddfisher commented on May 26, 2016

   

   ddfisher

   on May 26, 2016

   CollaboratorAuthor

   More actions

   Yeah, showing stuff like *args information seems good. I think we should aim for a sort of PEP 484++ syntax, which is a superset of PEP 484 syntax with additional information where appropriate (and we should try to think a carefully what that additional info looks like).

   I like the idea of alignment for the type difference mode. I don't think there should be any other difference in how the types are printed, though. In particular, I think we should always print full types and never abbreviate.
4. berdario commented on Jun 15, 2016

   

   berdario

   on Jun 15, 2016

   More actions

   I just stumbled upon this problem as well... I wondered why the error happened only when using classes that I defined (like RateType and not by using primitives (int, str))... until I realized it might've been the length of the string representation of the type itself, and I managed to reduce the test case I was using to

   from typing import Tuple
   
   class AAAAAAA: pass
   
   class BBBBBBBBBBBBB: pass
   
   def f(v: Tuple[AAAAAAA, AAAAAAA, BBBBBBBBBBBBB]):
       pass
   
   f((BBBBBBBBBBBBB(), AAAAAAA(), AAAAAAA()))
   

   which yields the puzzling error:

   Argument 1 to "f" has incompatible type tuple(length 3); expected tuple(length 3)
   
5. ilevkivskyi commented on May 18, 2018

   

   ilevkivskyi

   on May 18, 2018

   Member

   More actions

   Mypy now shows full types when necessary so this may be closed.
6. ilevkivskyi

   closed this as completedon May 18, 2018