std.random2

[H. S. Teoh]

On Tue, Jan 08, 2013 at 07:46:46PM +0100, Joseph Rushton Wakeling wrote:
> On 01/08/2013 07:38 PM, ixid wrote:
> >I imagine there has been some detailed discussion of the std.nameX
> >idea of libraries so forgive me if this has been discussed.
> 
> I appreciate your concern on this point, but I don't think it's the
> right thing to focus on in this specific discussion.
> 
> What I really want address is: how do we get the design of std.random
> _right_?
> 
> How we go about incorporating that new design into Phobos with
> minimal hassle for users is a different issue and one we can face
> when the time comes.

For one thing, I'd say definitely make RNGs have reference semantics.
Passing by value just doesn't make sense; for large generators it
consumes too much stack space and risks stack overflow, and in any case
copying RNGs unintentionally causes duplicated sequences, which is very
bad.

For those cases where you *want* to copy an RNG, it should be made into
a forward range and then you use .save explicitly.

I wonder if it even makes sense to force RNGs to inherit from a common
base class, so that reference semantics are enforced even for
user-defined types. But this may be a bit too heavy-handed (and it will
alienate the no-GC crowd).


T

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