This small snippet came about as a result of this discussion on python-ideas, requesting a new syntax for dynamically reevaluating a function each time it is called.
This snippet implements a simple decorator to do so without added syntax.
Python, 49 lines
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Copy to clipboard1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 | #! /usr/bin/env python3
from inspect import getsource
from functools import wraps
# get the globals out of the way
a, b, c = 0, 1, 2
def runtime(f):
"""Evaluates the given function each time it is called."""
# get the function's name
name = f.__name__
# and its source code, sans decorator
source = remove_decorators(getsource(f))
@wraps(f)
def wrapped(*args, **kwargs):
# execute the function's declaration
exec(source)
# since the above overwrites its name in the local
# scope we can call it here using eval
return eval("%s(*%s, **%s)" % (name, args, kwargs))
return wrapped
def remove_decorators(source):
"""Removes the decorators from the given function"""
lines = source.splitlines()
new_source = '\n'.join((line for line in lines if not line.startswith('@')))
return new_source
@runtime
def example1(x, y=[]):
y.append(x)
return y
@runtime
def example2(x=a**2+2*b+c):
return x
if __name__ == "__main__":
print("Testing example1")
print(example1(1))
print(example1(2))
print(example1(3))
print()
print("Testing example2 with default values")
print(example2())
print("Changing a to 5")
a = 5
print(example2())
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