xxxInPlace or xxxCopy?

[Jerry Quinn]

Andrei Alexandrescu Wrote:

> On 1/19/11 6:53 PM, Jonathan M Davis wrote:
> > On Wednesday, January 19, 2011 15:33:16 Andrei Alexandrescu wrote:
> >> I'm consolidating some routines from std.string into std.array. They are
> >> specialized for operating on arrays, and include the likes of insert,
> >> remove, replace.
> >>
> >> One question is whether operations should be performed in place or on a
> >> copy. For example:
> 
> So I guess vote stays unchanged :o).
> 
> >> Thoughts?
> >
> > Haven't we been using the approach that string operations generally make copies
> > (in many cases slices) and marking functions that do it in place with InPlace?
> 
> Problem is, even though the example uses strings, the functions apply to 
> all arrays.

The big difference is operating on immutable arrays vs mutable ones.  For immutable arrays, you  have to do copies.  But mutable ones allow in-place editing.  If I'm working with mutable arrays of ints, I don't want to have to type InPlace after every function and I *really* don't want the array to be copied or efficiency will go down the tubes.

Nor do I want to add Copy to every string operation.  This might be an argument to leave the string functions where they are.  To a certain extent, strings are special, even though they really aren't.

Is it too ugly to contemplate algorithms doing in-place operations on mutable arrays and return a copy instead for immutable ones?