Transience of .front in input vs. forward ranges

[H. S. Teoh]

On Tue, Nov 06, 2012 at 05:49:44AM +0100, Tommi wrote:
> On Tuesday, 6 November 2012 at 04:31:56 UTC, H. S. Teoh wrote:
> >The problem is that you can't do this in generic code, because
> >generic code by definition doesn't know how to copy an arbitrary
> >type.
> 
> I'm not familiar with that definition of generic code. But I do feel
> that there's a pretty big problem with a language design if the
> language doesn't provide a generic way to make a copy of a variable.
> To be fair, e.g. C++ doesn't provide that either.

OK I worded that poorly. All I meant was that currently, there is no
generic way to make a copy of something. It could be construed to be a
bug or a language deficiency, but that's how things are currently.

One *could* introduce a new language construct for making a copy of
something, of course, but that leads to all sorts of issues about
implicit allocation, how to eliminate unnecessary implicit copying,
etc.. It's not a simple problem, in spite of the simplicity of stating
the problem.


T

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