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

Brett C. bac at OCF.Berkeley.EDU
Fri Aug 20 18:29:00 CEST 2004

Barry Warsaw wrote:

On Thu, 2004-08-19 at 19:12, Brett C. wrote:

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 testpep292 all pass. What do you think about this compared to Tim's pattern, which is more strict than just complaining about $'s at the end of strings?

That is coming down to a question of convenience compared to explicitness. Do we want "Give me $1,000,000 now!" to raise ValueError, or do we want to let it pass through?

"Explicit is better than implicit" is good since it will cut down on errors (which is what Tim is arguing for along with "Special cases aren't special enough to break the rules").

But Raymond is pushing for "practicality beats purity" which is more or less true, but I am starting to agree with Tim that dollar amounts in an interpolated string probably won't hapeen that often. If anything the number will be what is interpolated in. So going for a more explicit version is seeming to be the better solution. Perk of the current implementation is that if someone wants a looser definition they can just change the regex themselves (you guys could even go as far as to break up the regex into individual class attributes and just have a property that does a '|'.join on them as a read method so it is even easier to just change the one group).

So I guess it's your call, Mr PEP Champion, on whether you want all individual, non-interpolating $ signs to lead to an error or just random orphaned ones at the end of the line.

-Brett

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