[Python-Dev] Re: Update PEP 292 (original) (raw)

Brett C. bac at OCF.Berkeley.EDU
Fri Aug 20 01:12:54 CEST 2004

Barry Warsaw wrote:

On Thu, 2004-08-12 at 01:19, Tim Peters wrote:

I do object to this part: If the $ character appears at the end of the line, or is followed by any other character than those described above, it is treated as if it had been escaped, appearing in the resulting string unchanged. There's already a facility to escape ,andit′sdeadeasytouse., and it's dead easy to use. ,andit′sdeadeasytouse. isn't a frequently needed character either in most apps. So escaping $ "by magic" too is, I think, more likely to make typing errors harder to find than to do anyone real good. What would you do about $'s at the end of the string? I think the implementation would be much more complex if you didn't have this rule, e.g. you'd have to match $$ and the $-placeholder regexps would basically have to match everything. Then the .sub call would have to be more complex too, because it would have to check for the existence of those match groups and then raise an exception. Or something like that.

Got an implementation and it's simple. =) It only required one additional group at the end (r"(?<!$)($)$") in the regex and a test if it matched.

I tested against "$$" to be fine but for "blah "and"" and ""and"" to raise an exception. Those all work and the tests in test_pep292 all pass.

If Barry is okay with this I can apply the patch and update the tests and the PEP. Do need to know what exception to raise when this does occur, though. ValueError?

-Brett

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