Question

What is the reason of having globals() function in Python? It only returns dictionary of global variables, which are already global, so they can be used anywhere… I’m asking only out of curiosity, trying to learn python.

def F():
    global x
    x = 1

def G():
    print(globals()["x"]) #will return value of global 'x', which is 1

def H():
    print(x) #will also return value of global 'x', which, also, is 1

F()
G()
H()

I can’t really see the point here? Only time I would need it, was if I had local and global variables, with same name for both of them

def F():
    global x
    x = 1

def G():
    x = 5
    print(x) #5
    print(globals()["x"]) #1

F()
G()

But you should never run into a problem of having two variables with same name, and needing to use them both within same scope.

Answer 1

Python gives the programmer a large number of tools for introspecting the running environment. globals() is just one of those, and it can be very useful in a debugging session to see what objects the global scope actually contains.

The rationale behind it, I’m sure, is the same as that of using locals() to see the variables defined in a function, or using dir to see the contents of a module, or the attributes of an object.

Coming from a C++ background, I can understand that these things seem unnecessary. In a statically linked, statically typed environment, they absolutely would be. In that case, it is known at compile time exactly what variables are global, and what members an object will have, and even what names are exported by another compilation unit.

In a dynamic language, however, these things are not fixed; they can change depending on how code is imported, or even during run time. For that reason at least, having access to this sort of information in a debugger can be invaluable.