On 23.10.2011 17:46, Dmitry Olshansky wrote:
On 23.10.2011 11:28, Rainer Schuetze wrote:
On 22.10.2011 21:05, Dmitry Olshansky wrote:
On 22.10.2011 20:56, Rainer Schuetze wrote:
I haven't followed the discussion closely, and I cannot really comment
on the core regex functionality, but I did actually use FReD as a
replacement of a buggy std.regex once.
In that case I wanted to have a lazily created static regex, but I did
not find an official way to test whether a Regex has been initialized:
static Regex!char re;
if(!isInitializedRE(re))
re = regex(r"^(.*)\(([0-9]+)\):(.*)$");
So I implemented isInitializedRE() as "re.ir !is null" for std.regex
and
"re.captures() > 0" for fred, but that fails for being a "drop-in
replacement".
Coincidentally, you still can access re.ir property in this way.
Wow, I wonder how far with backwards compatibility I can go :)
In both cases this relies on undocumented features.
Even now I can suggest a more portable and entirely generic way:
if(re == Regex!(char).init)
{
//create re
}
Though that risks doing more work then needed.
I think, both versions use implementation specifics, maybe there should
be a documented way to test for being initialized.
Definitely. How about adding an empty property + opCast to bool, with
that you'd get:
if(!re)
{
//create re
}
and a bit more verbose:
if(re.empty)
{
//create re
}
I think, this might be confused with normal usage, like "is this regex
the empty string?" (Is "" a valid regex?). Maybe a more explicite
"valid()" predicate would be fine.
"" is a valid regex that matches anywhere, with global flag it will
match before any codepoint + once at end.
I'm not sure using 'valid' is good, it may mislead user to check it all
over the place e.g.:
auto r = regex("blah");
if(r.valid())
....
You may be right. Maybe 'initialized', otherwise 'empty' isn't too bad
as well. But I think it should be explicite, so I would not add opCast
to bool.
