"Sean Kelly" <sean@f4.ca> wrote in message news:dt5d4e$i49$2@digitaldaemon.com...
> Walter Bright wrote:
>> C/C++ have gone the odd route of making the library *part of the language*, so, for example, a compiler can recognize strlen and replace it with custom code. To my mind this gives the worst of both worlds - no syntactic sugar and no library flexibility.
> I've heard this mentioned before and it seems a bit odd to me.  Does the spec actually mention this anywhere, or is it merely implied by having the library spec be a part of the language spec?

I think it's implied by it being part of the language spec. Regardless, it is true, and many compilers (including DMC) take advantage of it.

Georg Wrede wrote:
> Walter Bright wrote:
> 
>> "Georg Wrede" <georg.wrede@nospam.org> wrote in message news:43F53BE5.8020900@nospam.org...
>>
>>> Using regexps in C needs a total change of paradigm. Regexps are
>>> kind of "top down" things, wherease traditionally "peeking into
>>> strings" is bottom-up programming.
>>>
>>> You'd also have to learn regexps. The trivial things are trivial in
>>>  C-style too, and the non-trivial stuff gets avoided because of the
>>>  up-front investment. Folks rather do nested ifs and stuff.
>>>
>>> Conversely, many interpreted languages make it inefficient to do
>>> "peek" kind of programming, as compared to using regexps.
>>
>>
>> There are a lot of cool things you can do in script languages because
>> they are interpreted, and one doesn't care about efficiency. Those
>> things are simply incompatible with D. But I don't see any inherent
>> advantages script languages should have in implementing regex.
> 
> 
> Neither do I.
> 
> But the question was, how come regexps aren't _used_ as much as we'd expect.

My answer is that regular expressions simply aren't powerful enough for the kinds of string processing that I need to do regularly (no pun intended).  Regular expressions represent regular languages.  Not all languages are regular, of course.

<rant>
My other beef with regular expression are that there are so many competeing standards for them, and on top of that some are not even standardized (i.e. MS Visual Studio .NET 2003).

You never know if one implementation uses longest-match or one uses shortest-match; you never know how newlines are handled; you never know if Unicode is supported; you never know the run-time performance of your regex; you never know the syntax for selecting match indicies (0 based or 1 based, use '\1'? Record match with {} or with \(\) or with () ??) etc.

There are simply too many variables with regular expressions as they exist in all their forms to be relied upon.  Finally, they're just plain ugly and nearly impossible to debug.
</rant>

Following that rant, I can put a positive spin here and say that Ragel state machine compiler is an excellent model to work from!  One can insert custom code between state transitions for debugging and even for complex logic!  Why can't we have compiler-support for this type of power? :)

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James Dunne