scope of eval function in python

Question

Consider the following example:

i=7
j=8
k=10
def test():
    i=1
    j=2
    k=3
    return dict((name,eval(name)) for name in [\'i\',\'j\',\'k\'])
         


        

Answer 1

Generators are implemented as function scopes:

The scope of names defined in a class block is limited to the class block; it does not extend to the code blocks of methods – this includes generator expressions since they are implemented using a function scope.

So, the generator inside the dict() constructor has its own locals() dictionary. Now let's take a look at Py_eval's source code, specially when both globals() and locals() are None:

if (globals == Py_None) {
        globals = PyEval_GetGlobals();
        if (locals == Py_None)
            locals = PyEval_GetLocals();
    }

So, for your example PyEval_GetLocals() will be empty at the moment the loop is executing and globals() will be the global dictionary. Note that i, j and k defined inside the function are not in local scope of generator, rather they are in its enclosing scope:

>>> dict((name,eval(name, globals(), {})) for name in ['i', 'j', 'k'])
{'i': 7, 'k': 10, 'j': 8}