Michel Fortin wrote:
On 2009-02-19 00:50:06 -0500, Bill Baxter <[email protected]> said:
On Thu, Feb 19, 2009 at 2:35 PM, Andrei Alexandrescu
In general I'm weary of unwitting operator overloading, but I think this
case is more justified than others. Thoughts?
No. ~ means matching in Perl. In D it means concatenation. This
special case is not special enough to warrant breaking D's convention,
in my opinion. It also breaks D's convention that operators have an
inherent meaning which shouldn't be subverted to do unrelated things.
Indeed. That's why I don't like seeing `~` here.
What about turning it around and using 'in' though?
foreach(e; regex("a[b-e]", "g") in "abracazoo")
writeln(e);
The charter for "in" isn't quite as focused as that for ~, and anyway
you could view this as finding instances of the regular expression
"in" the string.
That seems reasonable, although if we support it it shouldn't be limited
to regular expressions for coherency reasons. For instance:
foreach(e; "co" in "conoco")
writeln(e);
should work too. If we can't make that work in the most simple case,
then I'd say it shouldn't with the more complicated ones either.
Well I'm a bit unhappy about that one. At least in current D and to
yours truly, "in" means "fast membership lookup". The use above is
linear lookup. I'm not saying that's bad, but I prefer the non-diluted
semantics. For linear search, there's always find().
By the way, regular expressions should work everywhere where we can
search for a string. For instance (from std.string):
auto firstMatchIndex = find("conoco", "co");
should work with a regex too:
auto firstMatchIndex = find("abracazoo", regex("a[b-e]", "g"));
If you mean typeof(firstMatchIndex) to be size_t, that's unlikely to be
enough. When looking for a regular expression, you need more than just
an index - you need captures, "pre" and "post" substrings, the works.
That's why matching a string against a regex must return a richer
structure that can't be easily integrated with std.algorithm.
Andrei
