Re: [boost] sorting library proposal

Subject: Re: [boost] sorting library proposal
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2009-06-04 11:36:36

Steven Ross wrote
On Thursday, June 04, 2009 10:41 AM
>
> Is there a good way to issue a compile-time warning telling
> people that integer_sort or float_sort isn't being used,
> because they passed in an incompatible data type?  I see
> static assertions, but what I need is an equivalent static
> warning, after which I use std::sort.

I'm not aware of any.

> Also, I'm using a simple if to decided this:
>
> if(sizeof(Div_type) <= sizeof(size_t))
>
> because enable_if appears to only work with classes.  I'm

enable_if_c works with any Boolean expression.

> assuming here that the compiler is smart enough to figure
> out that the expression is constant and to only bring in the
> code if it's true.  It would be nice to be able to eliminate
> the compiler warnings about size, and issue a more concise
> and meaningful message telling the user that their data type
> is too big for integer_sort (or incompatible with
> float_sort, as appropriate).

If you forward to an implementation class template with a bool template parameter defaulted to sizeof(Div_type) <= sizeof(size_t), you can partially specialize for the false case to provide the alternative implementation.  Thus, your algorithm invokes a static member function of the implementation class to select the appropriate implementation via compile time dispatch.

_____
Rob Stewart                           robert.stewart_at_[hidden]
Software Engineer, Core Software      using std::disclaimer;
Susquehanna International Group, LLP  http://www.sig.com

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