Marc Mutz <marc@klaralvdalens-datakonsult.se> writes:
On Monday 03 July 2006 00:14, Jeff Garland wrote:
I assume you meant
s = s.trim();
After renaming trim_copy(), yes. Otherwise no.
Well, that's very persuasive although I think it's harder to write
something modifies a collection of objects in place -- no?
Very good point. With a mutating trim(), people are tempted to write
std::for_each( v.begin(), v.end(), mem_fn( &super_string::trim ) );
which, strictly speaking, is not explicitly allowed by the std, IIRC. With a
const trimmed(), the user would be forced to use
std:transform(v.begin(),v.end(),v.begin(),mem_fn(&super_string::trimmed));
which much better conveys what the code does.
Don't get me
wrong, I'm pretty fond of immutable value types. Most of date_time is
written as immutable value types with a couple exceptions. However, in
this case I'm building on a base type that's already mutable and it seems
to me that it's pretty natural to say s.replace_all(...).
It's only natural b/c it's what people are used to. It's much easier, IMHO, to
work with immutable types,
In general, yes, and I would oppose the acceptance of a new C++ string class into Boost if it weren't immutable. And once you know it's immutable, you don't need naming contortions like "trim_copy." "trim" will do nicely. -- Dave Abrahams Boost Consulting www.boost-consulting.com