Are the keys of a kwargs argument to Python function guaranteed to be type string?

Question

def func(**kwargs):
   for key, value in kwargs.items():
      # Is key always going to be a string?
      # Could it have spaces?
      pass

Two qu

Answer 1

The keywords in kwargs should follow the rules of variable names, full_name is a valid variable name (and a valid keyword), full name is not a valid variable name (and not a valid keyword).

From PEP 362 -- Function Signature Object:

A Parameter object has the following public attributes and methods:
name : str
- The name of the parameter as a string. Must be a valid python identifier name (with the exception of POSITIONAL_ONLY parameters, which can have it set to None.)

And, from the Docs:

2.3. Identifiers and keywords:
... Within the ASCII range (U+0001..U+007F), the valid characters for identifiers are the same as in Python 2.x: the uppercase and lowercase letters A through Z, the underscore _ and, except for the first character, the digits 0 through 9. ...