What is the python way to define a (non-class) type like:
typedef Dict[Union[int, str], Set[str]] RecordType
2 Answers
This would simply do it?
from typing import Dict, Union, Set
RecordType = Dict[Union[int, str], Set[str]]
def my_func(rec: RecordType):
pass
my_func({1: {'2'}})
my_func({1: {2}})
This code will generate a warning from your IDE on the second call to my_func, but not on the first. As @sahasrara62 indicated, more here
In case users look for a distinct nominal typedef:
from typing import Dict, Union, Set, NewType
RecordType = Dict[Union[int, str], Set[str]]
DistinctRecordType = NewType("DistinctRecordType", Dict[Union[int, str], Set[str]])
def foo(rec: RecordType):
pass
def bar(rec: DistinctRecordType):
pass
foo({1: {"2"}})
bar(DistinctRecordType({1: {"2"}}))
bar({1: {"2"}}) # <--- this will cause a type error
This snippet demonstrates that only explicit casting will do.
$ mypy main.py
main.py:14: error: Argument 1 to "bar" has incompatible type "Dict[int, Set[str]]"; expected "DistinctRecordType"
Found 1 error in 1 file (checked 1 source file)
