[Python-Dev] pre.sub's broken under 2.2

[Tim Peters]

[/F]
> just for the record, one of those "let's change a lot of
> code that we don't understand, just because we can"

In the case of try + bare-except, it was more a case of "let's change code
we don't understand because it's impossible to guess its intent and that's
bad for future maintenance".

> things broke the "pre" module in 2.2.
>
> someone changed:
>
>             try:
>                 repl = pcre_expand(_Dummy, repl)
>             except:
>                 m = MatchObject(self, source, 0, end, [])
>
> to
>
>             try:
>                 repl = pcre_expand(_Dummy, repl)
>             except error:
>                 m = MatchObject(self, source, 0, end, [])
>
> but in the most common use case (replacement strings
> containing group references), the pcre_expand function
> raises a TypeError exception...

Like I said <wink>.  The except clause should list the exceptions it
specifically intends to silence, and something as obscure as this case
deserves a comment to boot.

I also note that if this passed the tests, then the test suite wasn't even
trying "the most common use case".

there's-more-than-one-kind-of-breakage-illustrated-here-ly y'rs  - tim