Nsryjdtyk

I have a python script as a string, as example:

exec("sent = {'test': 1}")

global sent

print(sent)

I executed it using exec function, then I accessed the variable using global python command. This way works without problem without using classes, but when I have the same code in a class, like:

class example:

    def fun1(self):

        exec("sent = {'test': 1}")

        global sent

        print(sent)



v = example()

print(v.fun1())

I get the following error:

NameError: name 'sent' is not defined

You are not passing the global dictionary to modify. Try:

 exec("sent = {}",globals())

You really should avoid using global variables. Regardless, here's how to do it:

class example:

    def fun1(self):

#        globals sent  # Not needed in this special case.

        exec("sent = {}", globals())

        print('in fun1, "sent" is now', sent )





v = example()

print(v.fun1())  # Result will be None because fun1() doesn't return anything.

print('after call to fun1(), global "sent" is', sent)

Output:

in fun1, "sent" is now {}

None

after call to fun1(), global "sent" is {}

A global declaration only does something inside a function or class method and even then is only needed when the global variable's value is going to be set to something.
However, as a special case, one isn't really needed here in the fun1() method because it explicitly passes globals() (but not a separate locals dict) when it calls exec(). It might be a good idea to put one in anyway to make it more clear what's going on.

Using exec() this way is explained in its documentation which says:

If only globals is provided, it must be a dictionary, which will be used for both the global and the local variables.

(emphasis mine)

Here's a way to avoid referencing a global variable at all in the method:

class example:

    def fun1(self):

        namespace = {}

        exec("sent = {}", namespace)

        sent = namespace['sent']  # Retrieve result.

        print('in fun1, "sent" is now', sent )

        return sent



v = example()

sent = v.fun1()

print('after calling fun1(), "sent" got set to', sent)

Output:

in fun1, "sent" is now {}

after calling fun1(), "sent" got set to {}