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From: Jeff Garland (jeff_at_[hidden])
Date: 2006-07-03 09:08:54

Marc Mutz wrote:

> 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.

There's no restriction on for_each. I think the value of transform versus
for_each for this case is marginal at best. As for trim versus trimmed, I'm
afraid I don't like trimmed much. It's 'past tense'. To my ear it strikes as
odd -- like the operation is already done. I normally think of mutating
functions a present tense verbs. Just looking around a bit,
Boost.string_algo-trim, QTString-trimmed, Java.String-trim, RWCString-strip --
so it's not that consistent. As much as anything I'm leveraging
Boost.string_algo here, so consistent naming is a virtue.

Hopefully this won't make you mad, but your prior email made me realize that
the mutating functions should return a self reference so now you can write:

  s.trim().to_upper().append(" more stuff ");

The other thing it made me realize is that it would be handy to have
additional overloads on the number of parameters in append/insert_at. So in
the next version you'll be able to write:

double dbl = 1.12345;
int i = 100;

s.append(dbl, " a string ", i);
//"1.12345 a string 100"

I'll probably do something like boost.tuple and support up to 10 arbitrary
parameters. And at the suggestion of someone else, I'm also adding
boost.format into the mix:

s.append_formatted(dbl, "-some string-", i, "%-7.2f %s %=5d");
//"1.12 -some string- 100 "

So I'm afraid I'm making it more mutable, not less ;-)


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