Why is using not() operator sometimes a SyntaxError? [duplicate]

Question

This works:

>>> not(True)
False
>>> a = {}
>>> a["hidden"] = False
>>> a["hidden"] = not(a["hidden"])
>>> a["hidden"]
True

but not this:

def toggleHelp(self, event):
    # https://stackoverflow.com/questions/10267465/showing-and-hiding-widgets#10268076
    if (self.special_frame["hidden"] == False):
        self.special_frame.grid_remove()
    else:
        self.special_frame.grid()
    self.special_frame["hidden"] == not(self.special_frame["hidden"])

error

 line 563
    self.special_frame["hidden"] == not(self.special_frame["hidden"])
                                      ^
SyntaxError: invalid syntax

in the init:

self.special_frame["hidden"] = False

What I am doing wrong ?

Answer 1

The problem is the use of == where you need =. This normally wouldn't cause a syntax error, but in your case, you have:

a == not(b)

which is the same as:

a == not b

This groups as:

(a == not) b

and that causes the syntax error.

An assignment operator, on the other hand, has lower precedence, so:

a = not b

groups as:

a = (not b)

which is fine.

Answer 2

I'm pretty sure you only need one equal sign, maybe that's the mistake. = is for assignement and == is used for comparison.