validation - how do I convert a string to a valid variable name in python?

Question

I need to convert an arbitrary string to a string that is a valid variable name in python.

Here's a very basic example:

s1 = 'name/with/slashes'
s2 = 'name '

def clean(s):
    s = s.replace('/','')
    s = s.strip()
    return s

print clean(s1)+'_'#the _ is there so I can see the end of the string

That is a very naive approach. I need to check if the string contains invalid variable name characters and replace them with ''

What would be a pythonic way to do this ?

Answer 1

Well, I'd like to best Triptych's solution with ... a one-liner!

>>> def clean(varStr): return re.sub('W|^(?=d)','_', varStr)
...

>>> clean('32v2 g #Gmw845h$W b53wi ')
'_32v2_g__Gmw845h_W_b53wi_'

This substitution replaces any non-variable appropriate character with underscore and inserts underscore in front if the string starts with a digit. IMO, 'name/with/slashes' looks better as variable name name_with_slashes than as namewithslashes.