[ccan] [PATCH 2/4] order_functions: Scalar comparison functions

[David Gibson]

On Tue, Jun 02, 2015 at 10:36:41AM +0930, Paul 'Rusty' Russell wrote:
> David Gibson <david at gibson.dropbear.id.au> writes:
> > Extend the order_functions module to provide simple, standard, comparison
> > callbacks for scalar types (i.e. integer and floating point types).
> >
> > In addition to the usual variants comparing a plain scalar, this also
> > provides helper macros to construct a suitably typed callback and context
> > pointer to order structures by a specified scalar field.
> 
> This is *so awesome!*, I think many of my funcs can be
> trivially replaced by these.
> 
> Two things:
> 1) Should we just expose the macro in the header, and be done?
>    Hmm, I'd say not, since asort() won't be inlined anyway.

Um.. I'm not entirely sure what you're getting at here.

>    But maybe s/SCALAR_ORDER/ORDER_SCALAR/ for namespace reasons
>    and leave that in the header, with a /* You can build your own! */
>    comment?

I wondered about that.  The wrinkle is that the macro generates
exported functions, whereas in the most common case of creating your
own they'll want to be static.

Obviously the macro will only work for types which have C builtin <, >
and == implementations.  That doesn't actually leave a lot of options
that aren't already covered in the module - basically just typedef
aliases to integer types.  I'm not sure how worthwhile leaving the
macro in the header just for that is.

> 2) I'd prefer, despite the extra typing, to have the explicit
>    declarations in the header anyway.  It's just far more readable.

By this I'm assuming you mean get rid of the _DECL_ONAME_* macros and
just fully expand them in the header?

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson
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