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Merged
JukkaL merged 14 commits into from
Mar 18, 2017
Merged

Implement default values on NamedTuple #2719

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40c32d3
implement namedtuple defaults
JelleZijlstra Jan 19, 2017
def572f
fix lint
JelleZijlstra Jan 19, 2017
8ce550a
temp: attempt defaults
JelleZijlstra Jan 20, 2017
6ba17b3
make test not use index to avoid interaction with line number bug
JelleZijlstra Jan 20, 2017
df36213
add more tests, add _field_defaults
JelleZijlstra Jan 20, 2017
44f381f
remove remnants of failed attempt
JelleZijlstra Jan 20, 2017
c8715b8
test that type errors inside the default are caught
JelleZijlstra Jan 20, 2017
6ad489b
don't analyze namedtuple decorators
JelleZijlstra Jan 23, 2017
291c059
add a test for strict_optional
JelleZijlstra Jan 23, 2017
88b63fb
don't use cast in test
JelleZijlstra Jan 24, 2017
1fe9792
fewer checks for is_namedtuple
JelleZijlstra Jan 24, 2017
51c3dc4
Merge branch 'master' into namedtupledefault
gvanrossum Mar 13, 2017
91acfc7
Merge branch 'master' into namedtupledefault
JelleZijlstra Mar 18, 2017
3df509a
add a few more tests
JelleZijlstra Mar 18, 2017
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add more tests, add _field_defaults
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@JelleZijlstra
JelleZijlstra committed Jan 23, 2017
commit df36213e546e0aefff8ba53c7ff826f90c8652dc
1 change: 1 addition & 0 deletions mypy/semanal.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1829,6 +1829,7 @@ def add_field(var: Var, is_initialized_in_class: bool = False,
tuple_of_strings = TupleType([strtype for _ in items], basetuple_type)
add_field(Var('_fields', tuple_of_strings), is_initialized_in_class=True)
add_field(Var('_field_types', dictype), is_initialized_in_class=True)
add_field(Var('_field_defaults', dictype), is_initialized_in_class=True)
add_field(Var('_source', strtype), is_initialized_in_class=True)

tvd = TypeVarDef('NT', 1, [], info.tuple_type)
Expand Down
55 changes: 46 additions & 9 deletions test-data/unit/check-class-namedtuple.test
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Expand Up @@ -294,6 +294,10 @@ class X(NamedTuple):
y: str

reveal_type(X._fields) # E: Revealed type is 'Tuple[builtins.str, builtins.str]'
reveal_type(X._field_types) # E: Revealed type is 'builtins.dict[builtins.str, Any]'
reveal_type(X._field_defaults) # E: Revealed type is 'builtins.dict[builtins.str, Any]'

[builtins fixtures/dict.pyi]

[case testNewNamedTupleUnit]
# flags: --fast-parser --python-version 3.6
Expand Down Expand Up @@ -349,10 +353,17 @@ import typing

class X(typing.NamedTuple):
x: int
y = None # type: int # E: Invalid statement in NamedTuple definition; expected "field_name: field_type"
x.__init__: int # E: Invalid statement in NamedTuple definition; expected "field_name: field_type"
y = 1
x.x: int
z: str = 'z'
aa: int # E: Non-default NamedTuple fields cannot follow default fields
aa: int

[out]
main:6: error: Invalid statement in NamedTuple definition; expected "field_name: field_type"
main:7: error: Invalid statement in NamedTuple definition; expected "field_name: field_type"
main:7: error: Type cannot be declared in assignment to non-self attribute
main:7: error: "int" has no attribute "x"
main:9: error: Non-default NamedTuple fields cannot follow default fields

[builtins fixtures/list.pyi]

Expand Down Expand Up @@ -380,7 +391,7 @@ main:8: error: Unsupported type Type["N"]

[case testNewNamedTupleWithDefaults]
# flags: --fast-parser --python-version 3.6
from typing import NamedTuple
from typing import List, NamedTuple, Optional

class X(NamedTuple):
x: int
Expand All @@ -390,6 +401,31 @@ reveal_type(X(1)) # E: Revealed type is 'Tuple[builtins.int, builtins.int, fall
reveal_type(X(1, 2)) # E: Revealed type is 'Tuple[builtins.int, builtins.int, fallback=__main__.X]'

X(1, 'a') # E: Argument 2 to "X" has incompatible type "str"; expected "int"

@ilevkivskyi ilevkivskyi Jan 19, 2017

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I would add few more test cases. For example, the None default value mentioned above, user defined classes as field types, wrong types like x: str = 5, etc.

@ilevkivskyi ilevkivskyi Jan 19, 2017

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Also it makes sense to add tests with classes inheriting form a named tuple with default values.

@JelleZijlstra JelleZijlstra Jan 20, 2017

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Thanks for these suggestions! The x: str = 5 case actually wasn't checked, and I had some trouble coming up with a way to make that throw an error, because the body of the NamedTuple is currently almost completely ignored. I managed to fix it by typechecking the body like a normal class. This has the side effect that some errors (stuff like x[0]: int) produce multiple errors on the same line, but that doesn't seem like a big deal.

X(1, z=3) # E: Unexpected keyword argument "z" for "X"

class HasNone(NamedTuple):
x: int
y: Optional[int] = None

@ilevkivskyi ilevkivskyi Jan 20, 2017

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Thank you for writing more tests. I will be even more happy if you add few more tests for these (also with --strict-optional)


reveal_type(HasNone(1)) # E: Revealed type is 'Tuple[builtins.int, builtins.int, fallback=__main__.HasNone]'

class Parameterized(NamedTuple):
x: int
y: List[int] = []

reveal_type(Parameterized(1)) # E: Revealed type is 'Tuple[builtins.int, builtins.list[builtins.int], fallback=__main__.Parameterized]'
Parameterized(1, ['not an int']) # E: List item 0 has incompatible type "str"

class Default:
pass

class UserDefined(NamedTuple):
x: Default = Default()

reveal_type(UserDefined()) # E: Revealed type is 'Tuple[__main__.Default, fallback=__main__.UserDefined]'
reveal_type(UserDefined(Default())) # E: Revealed type is 'Tuple[__main__.Default, fallback=__main__.UserDefined]'

[builtins fixtures/list.pyi]

[case testNewNamedTupleWrongType]
# flags: --fast-parser --python-version 3.6
Expand All @@ -401,14 +437,15 @@ class X(NamedTuple):

[case testNewNamedTupleInheritance]
# flags: --fast-parser --python-version 3.6
from typing import NamedTuple
from typing import cast, NamedTuple

class X(NamedTuple):
x: int
x: str
y: int = 3

class Y(X):
def method(self) -> int:
return self.x + self.y
def method(self) -> str:

@JukkaL JukkaL Mar 18, 2017

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Test calling base class __init__ in a subclass of a named tuple.

return self.x + cast(str, self.y)

@ilevkivskyi ilevkivskyi Jan 23, 2017

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To be honest, I don't like casts of unsafe expressions in tests, but formally this test works as it should.
Maybe you could modify it?

@JelleZijlstra JelleZijlstra Jan 24, 2017

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I'll just change it to access self.y without using it. I did str(self.y) first but that doesn't work because the fixture doesn't have it.


reveal_type(Y(1)) # E: Revealed type is 'Tuple[builtins.int, builtins.int, fallback=__main__.Y]'
reveal_type(Y('a')) # E: Revealed type is 'Tuple[builtins.str, builtins.int, fallback=__main__.Y]'
Y(y=1, x='1').method()