[RFC] replaceInto

[Timon Gehr]

On 03/04/2012 09:48 PM, Dmitry Olshansky wrote:
> This is proposal was dictated by a simple sudden need when designing
> with ranges in mind. It's to introduce into Phobos the idiomatic
> function replaceInto taking an output range to store the result in.
>
> The signature revolves around:
> void replace(..., Sink)(..., Sink sink)
> if(... && isOutputRange!Sink)
>
> Motivating example (std.array replace):
>
> auto writer = stdout.lockingTextWriter; //or pick an Appender
> foreach(line; stdin.byLine)
> writer.put(replace(line, "Nick", "Nicholas"));
>
>
> Skiping hardcoded strings, and lockingTextWriter (it has problems) at
> the very deep level we see - what exactly? A horrible inefficiency, of
> course! There is no need to allocate space for replaced string and even
> doing it on buffer in-place risks allocation.
>
> With proposed replaceInto:
>
> auto writer = stdout.lockingTextWriter; //or pick an Appender
> foreach(line; stdin.byLine)
> replaceInto(line, "Nick", "Nicholas", writer);
>
> Look ma, no allocations!
>
> Same goes for e.g. std.regex replace, coincidence, coincidence :)
>
> P.S. A DIP 9 flashback?
>
>

Yes, we need this.