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From: Marc Mutz (marc_at_[hidden])
Date: 2006-07-03 03:03:02

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, b/c the interface is consistent. You have a point
when you say that std::string is a mutable type and you're building on it.
That doesn't mean, however, that you need to keep it's baggage. :)


Marc Mutz -- marc_at_[hidden], mutz_at_[hidden]
phone: +49 521 521 45 45; mobile: +47 45 27 38 95
Klarälvdalens Datakonsult AB, Platform-independent software solutions

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