Question

Is it possible to call a function without first fully defining it? When attempting this I get the error: “function_name is not defined”. I am coming from a C++ background so this issue stumps me.

Declaring the function before works:

def Kerma():
        return "energy / mass"    

print Kerma()

However, attempting to call the function without first defining it gives trouble:

print Kerma()

def Kerma():
    return "energy / mass"

In C++, you can declare a function after the call once you place its header before it.

Am I missing something here?

Answer 1

One way that is sort of idiomatic in Python is writing:

def main():
    print Kerma()

def Kerma():
    return "energy / mass"    

if __name__ == '__main__':
    main()

This allows you to write you code in the order you like as long as you keep calling the function main at the end.