dale at riverhall.NOTHANKS.co.uk
Thu Jan 30 21:15:11 CET 2003
Alex Martelli <aleax at aleax.it> wrote:
>A class is string-like if it acts like a string. If a
>class lets its instances be concatenated to strings, it's
>pretty string-like -- all of str, unicode and UserString
>do, and no other type that's either built-in or the standard
>library. Making this easily checked feature the single
>discriminant of "string-likeness" appears quite OK to me
>for most purposes. You can wrap the test into highly readable
>form by the simple trick of defining a function;-)...e.g.:
> try: return x+'!'
> except TypeError: return False
There's a bit of a language deficiency here if you have to resort to
this type of obscure trick. To test for strings, I have always coded
type(var) in (str, unicode)
isinstance(var, (str, unicode))
But, where it mattered, I have also been able to make sure that my
string-like objects are subclasses of str.
It makes you think.
Riverhall Systems Ltd
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