Newbie - How to iterate list or scalar ?

[Diez B. Roggisch]

Andy Dingley wrote:

> I seem to be writing the following fragment an awful lot, and I'm sure
> it's not the best and Pythonic way to do things. Any advice on better
> coding style?
> 
> pluginVersionNeeded is a parameter passed into a method and it can
> either be a simple scalar variable, or it can be a list of the same
> variables.  My problem is how to iterate it, whether it's a a list or
> not.
> 
> I can't simply throw it into the for...in loop -- if the scalar
> variable were to be a string (which is considered to be atomic in my
> application) then Python sees this string as iterable and iterates over
> the characters in it!
> 
> 
>     versionsNeeded = pluginVersionNeeded
>     if isinstance( versionsNeeded, list):
>         versionsToTest = versionsNeeded
>     else:
>         versionsToTest = [ versionsNeeded ]
>     for versionNeeded in versionsToTest:
>         pass

Use a function. 

def listify(v):
    if not isinstance(v, list):
        return [v]
    return v

versionsToTest = listify(versionsNeeded)

Diez