Andrei Alexandrescu wrote:
Daniel Keep wrote:
Steven Schveighoffer wrote:
On Thu, 14 May 2009 09:55:08 -0400, Andrei Alexandrescu
<[email protected]> wrote:
Also, I dislike the signature int find() that returns -1 if not found.
Time and again experience shows that find() returning a range is much
better in real code because it works seamlessly when the
substring/element was not found (no more need for an extra test!)
Ech, returning -1 is the bane of Java and C#. The return value should
be the end of the string, regardless of whether it is a range or
index. I could never understand the mentality of returning -1 versus
end of
string.
-Steve
int idx = find(str);
if( idx == -1 ) doStuff;
- or -
if( idx == str.length ) doStuff;
I think Steve's point is that often you want to do something like:
auto before = str[0 .. find(str, something)];
or
auto after = str[find(str, something) .. $];
which behave nicely at limit conditions (when something isn't found). In
contrast, the version with -1 needs a separate varible and a test - a mess.
But most time, you want to know both _if_ something was found, and
where. Returning the length of the string makes checking if something
was found harder. That's also quite a mess.
Maybe a good way would be to return a pair of slices, before and after
something was found (ignoring that there are no MRVs):
(char[], char[]) myfind(char[] str, char[] tofind) {
int index = find(str, tofind); //returns str.length if not found
return str[0..index], str[index..$];
}
This would give the user lots of flexibility, without having to declare
useless temporaries, especially not for the first argument passed to
myfind().
For example: was something found?
bool found = myfind(bla, blubb)[1].length;
(That's still more elegant than to compare lengths.)
Andrei
