Rules for Python local assignment

The code is as follows:

MyVar = 1

Def myfunc ():
MyVar + = 1

MyFunc ()

will prompt for error:

Unboundlocalerror:local variable ' myVar ' referenced before assignment

Python proposes the following hypothesis: If you assign a value to a variable anywhere within the body of the function, Python adds the name to the local namespace.

Statement MyVar + = 1 assigns a value to the name MyVar, the MyVar is part of the local namespace of the function MyFunc, and it does not currently have an associated value, resulting in an error.

WORKAROUND: Use the global statement

The code is as follows:

MyVar = 1

Def myfunc ():
Global MyVar
MyVar + = 1

MyFunc ()

Scope Search Rules:

L: Native (local)

E: Closed (eclosing)

G: Overall (global)

B: Built-in (built-in)

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