From: David Abrahams (dave_at_[hidden])
Date: 2006-07-03 08:39:02
Marc Mutz <marc_at_[hidden]> 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
> 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
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