execute string with function into a function

Question

how to make the function test() work correctly?

Python 3.4.1

a function into string does not work well when this string is inside a function. how define this function that inside a string?

def func(x):
   return x+1
def test(a,b):
   loc = {'a':a,'b':b}
   glb = {}
   exec('c = [func(a+i)for i in range(b)]', glb,loc)
   c = loc['c']
   print(c)

print('out the function test()')
a= 1
b= 4
c = [func(a+i)for i in range(b)]
print(c)

'''results:

out the function test()
[2, 3, 4, 5]
>>> test(1,4)
Traceback (most recent call last):
  File "<pyshell#1>", line 1, in <module>
    test(1,4)
  File "C:\Users\Rosania\Documents\Edilon\Python examples\apagar.py", line 6, in test
    exec('c = [func(a+i)for i in range(b)]', glb,loc)
  File "<string>", line 1, in <module>
  File "<string>", line 1, in <listcomp>
NameError: name 'func' is not defined

'''

What in the blue blazes are you actually trying to do, and why? — Two-Bit Alchemist
– Two-Bit Alchemist, Commented Jan 12, 2015 at 23:01
At the very least, your glb should be {'func': func} otherwise the string you're execing obviously gives that "name 'func' is not defined" NameError you report -- where did you think it could resolve that name?! — Alex Martelli
– Alex Martelli, Commented Jan 12, 2015 at 23:02

Chad Miller · Accepted Answer · 2015-01-12 23:01:52Z

2

This is kind of evil to eval a string.

Assuming you know what you're doing...

Put "func" in the locals dict too. Your eval environments must know about everything you expect to reference in your eval'd string.

loc = {'a':a, 'b':b, 'func':func}

answered Jan 12, 2015 at 23:01

Chad Miller

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3 Comments

Edilon Junior Over a year ago

did not work test(1,4) Traceback (most recent call last): File "<pyshell#2>", line 1, in <module> test(1,4) File "C:\Users\Rosania\Documents\Edilon\Python examples\apagar.py", line 6, in test exec('c = [func(a+i)for i in range(b)]', glb,loc) File "<string>", line 1, in <module> File "<string>", line 1, in <listcomp> NameError: name 'func' is not defined >>>

Edilon Junior Over a year ago

maybe test() should be a class?

Edilon Junior Over a year ago

this is my true code, take a look: stackoverflow.com/questions/27913960/…

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