Python 3.6 inspect.signature() doesn't show arguments

Question

I have a function:

def report(start=1, quantity=100, days_left=7, min_app_version=None):

I want to get argument names and default values, something like

{'start':1, 'quantity':100, 'days_left':7, 'min_app_version':None}

(or at least two lists) from outside this function

when I do

import inspect
print(inspect.signature(report))

I get

(*args, **kwargs)

Why doesn't 'inspect.signature' see function arguments?

SOLVED: THE PROBLEM WAS BECAUSE OF A DECORATOR

I have Python 3.6 installed and works ok: the signature printed is `(start=1, quantity=100, days_left=7, min_app_version=None)` — Andrej Kesely, Jul 09 '18 at 15:26
Does `report` have any annotations or modified dynamically in any way? What does `inspect.getfullargspec(report)` show? — FHTMitchell, Jul 09 '18 at 15:28
@FHTMitchell it shows: FullArgSpec(args=[], varargs='args', varkw='kwargs', defaults=None, kwonlyargs=[], kwonlydefaults=None, annotations={}) — dimkor, Jul 09 '18 at 15:32
Great, glad you found a solution. You should post an answer to your own question (and show the code with the decorator). — FHTMitchell, Jul 09 '18 at 15:34

score 5 · Accepted Answer · answered Jul 09 '18 at 15:47

Even better than removing the decorator, you can tell the decorator to make the function wrapper look like the wrapped function to inspection tools using functools.wraps

Instead of

def decorator(f):
    def wrapper(*args, **kwargs):
        print("Wrapped")
        return f(*args, **kwargs)
    return wrapper

@decorator
def report(start=1, quantity=100, days_left=7, min_app_version=None):
    pass

print(inspect.signature(report))
# (*args, **kwargs)

You can do

from functools import wraps

def decorator(f):
    @wraps(f)
    def wrapper(*args, **kwargs):
        print("Wrapped")
        return f(*args, **kwargs)
    return wrapper

@decorator
def report(start=1, quantity=100, days_left=7, min_app_version=None):
    pass

print(inspect.signature(report))
# (start=1, quantity=100, days_left=7, min_app_version=None)

dimkor · Answer 2 · 2018-08-18T00:01:28.947

2

If anyone ever get stuck with this error, just delete the function decorator.

@time_count
def report(start=1, quantity=100, days_left=7, min_app_version=None):

You can also help yourself with: How to strip decorators from a function in Python

edited Aug 18 '18 at 00:01

answered Jul 09 '18 at 15:35

dimkor

71
1
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Python 3.6 inspect.signature() doesn't show arguments

2 Answers2