Why do I get the error: nameError: name tk is not defined, while I definded name tk?

I am making a code editor. But when I type in my code editor the following code, it is getting a NameError.

import tkinter as tk

class App(tk.Tk):
    def __init__(self):
        super().__init__()
        self.label = tk.Label(self, text="iets") # here, tk isn't recognized
        self.label.pack()
        
app = App()
app.mainloop()

All the code of the input tkinter text widget is executed by a exec statement. The whole NameError is:

Traceback (most recent call last): File "C:\Users\Gebruiker\PycharmProjects\mylanguage\execute.py", line 24, in do exec(self.input) File "< string>", line 9, in File "< string>", line 6, in __ init__ NameError: name 'tk' is not defined

Why do i get this error? in the code I typed in I do have import tkinter as tk!

The hierarchy of my project is the following: I've 8 files: main.py, execute.py, output.py et cetera

From main.py, the tkinter app is created.
When i press button run, in execute.py the code is, as it says, executed.
Then the output or error is being displayed in a toplevel window from the file output.py.

execute.py:

...
    def do(self):
        sys.stdout.write = output
        try:
            set_last("")
            exec(self.input) #line 24
        except Exception:
            set_last("text.config(foreground='red')")
            error = traceback.format_exc()
            output(error)
...

when i add print(repr(self.input)) on top of do() it outputs:

import tkinter as tk

class App(tk.Tk):
    def __init__(self):
        super().__init__()
        self.label = tk.Label(self, text="iets")
        self.label.pack()
        
app = App()
app.mainloop()

See the whole project on github: https://github.com/keizertje/myl

thanks in advance!

Solution

sorry for the consternation, the reason of my problem was totally other than i expected! the problem was that when i put self.input in exec() the program starts with all global variables. how to fix? as acw1668 said: simply use exec(self.input, {}) and it worked! this empty dict means that at the start of executing there are no global variables.

so do() becomes:

    def do(self):
        sys.stdout.write = output
        try:
            set_last("")
            exec(self.input, {}) # here it's fixed!
        except Exception:
            set_last("text.config(foreground='red')")
            error = traceback.format_exc()
            output(error)