Class ToCanonical

source code

                 object --+    
                          |    
basevalidator.BaseValidator --+
                              |
                             ToCanonical

Reduce strings to a canonical form.

A common problem in cleaning user input is to catch trivial variants, e.g. how to recognise 'foo-bar', 'Foo-bar', ' foo-bar ' and 'foo_bar' as being the same value. This function achieves that by stripping flanking spaces, converting letters to uppercase and converting internal stretches of spaces, underscores and hyphens to a single underscore. Thus, all of the previous values would be converted to 'FOO_BAR'.

For example:

>>> v = ToCanonical()
>>> v ('aBcD')
'ABCD'
>>> v ('  ab cd_')
'AB_CD_'
>>> v ('AB-_ CD')
'AB_CD'