how to import

[Fredrik Lundh]

Fedor wrote:

> [test1.py]
> #This setup doesn't work:
> import mx.DateTime
> class A:
>     def __init__(self):
>         print mx.DateTime.now()
>     def test(self):
>         print mx.DateTime.now()
>         import mx.ODBC
> a=A()
> #Results in: 2002-11-06 19:22:14.49
> a.test()
> #Results in: UnboundLocalError: local variable 'mx' referenced before
> assignment

full story:

http://www.python.org/doc/current/ref/naming.html
http://www.python.org/doc/current/ref/import.html

summary:

"import" behaves like any other assignment statement.

inside the test method, the "import mx.ODBC" statement attempts to
assign a value (the module object) to the "mx" variable.

the compiler notices this, and flags "mx" as a local variable.  since "mx"
is a local variable, you cannot refer to it before it has been assigned a
value.

to fix this, either add a "global mx" statement to the method, or move
the import statement to the top of the method.

</F>