mapping None values to ''

[Tim Chase]

> i wish to map None or "None" values to "".
> eg
> a = None
> b = None
> c = "None"
> 
> map( <something>  ,  [i for i in [a,b,c] if i in ("None",None) ])
> 
> I can't seem to find a way to put all values to "". Can anyone help?
> thanks

I'd consider this a VeryBadIdea(tm).  However, given Python's 
introspective superpowers, it *can* be done (even if it most 
likely *shouldn't* be done).  That caveat out of the way, here goes:

 >>> for scope in [locals, globals]:
...     s = scope()
...     for vbl, value in s.items():
...             if value == None or (type(value) == type("") and 
value == 'None'):
...                     s[vbl] = ''


seems to do the trick.  You may, likely, just want to operate on 
locals, not every last global variable in your project, in which 
case you can just use

	s = locals()
	for vbl, value in s.items():
		...

There may be some better way to determing whether an item is a 
string than my off-the-cufff

	type(value) == type("")

but it worked to prevent trying to compare non-strings to the 
string 'None' later in the sub-clause of the if statement.

Note that if you wrap this in a function, you'll may have to pass 
in locals() as a parameter because otherwise, inside your 
function, you'll have a different set of available locals that 
you did when you called the function. :)

Beware your foot when shooting this gun...it likes to aim at feet.

-tkc