Extract function argument from string

Question

I have something as follows:

mystring="myobject"
def foo(object):
 pass

And I would like to call foo(myobject) using mystring directly, in the same way like getattr(myclass, "mymethod").

Any help would be welcome. Thanks

• Jithin Pavithran: Can you detail more about what you need? Maybe the syntax you think should exist. I'm not clear whether you are looking for exec() function or a way to get argument of foo() inside foo() using something like getattr(). I can't think of a context where you will find the 2nd one handy.

Answer 1

You can resolve the value of myobjectfrom the module where it is defined with getattr. If it is in the main module, this should work:

import __main__
mystring = 'This is a test.'
def foo(object):
 print object
variableName = 'mystring'
foo(getattr(__main__, variableName))
variableName = 'variableName'
foo(getattr(__main__, variableName))

This should print

This is a test.

variableName

The import of the main module is necessary for variables from the main scope.

Edit: You can also get the content of the string with very dangerous eval(). Just replace foo(getattr(__main__, variableName)) with foo(eval(variableName)).

• Jithin Pavithran: How is this different from foo(mystring)? Yes it is, if there is some other mystring residing in a scope closer to foo().
• clemens: My code looks up for variable named mystring. The reason for that is, that you could use a variable instead of a string literal. See my edit.
• clemens: I've updated my post. If you use the content of mystring multiple times, you should parse it once with myvalue = eval(mystring), and use myvalue as parameter.
• Anass Elidrissi: @macmoonshine Thank you for the answer, except that I don't want ` object ` to be a string. To clarify: Let's say I have mystring = '[ (1,1), (2,2), (3,3) ]' , I want to call foo([ (1,1), (2,2), (3,3) ]) . There is the possibility to use exec('foo('+mystring+')' ) , but if foo had many arguments or the list inside mystring was used frequently, that wouldn't be quite efficient, and the exec is quite annoying with the return .
• clemens: Did you see my edit and my comment? What do you mean with your last sentence?