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Subject: Re: [boost] Call for interest - BOOST_AUTO_FUNCTION
From: Matt Calabrese (rivorus_at_[hidden])
Date: 2010-10-18 06:29:20

On Mon, Oct 18, 2010 at 4:41 AM, Matt Calabrese <rivorus_at_[hidden]> wrote:
> I could change the way the macro works by making it one single macro
> invocation. That's probably the better solution even though it was something
> I originally wanted to avoid. Not having to put "end" is a good enough
> reason for me to change the design.
> --
> -Matt Calabrese

Sorry for the triple reply. Even though it's not a difficult change, I'm
torn. My gripe with making it one macro is it implies extra surrounding
parentheses and simply looks a bit more cluttered and confusing. That sounds
like it's not a big deal, which it may not be, but it does at the very least
make the original use-case more complicated. After all, the reason it was
called "auto function" to begin with is because its original intent was to
deduce the return type. If you separate the declaration from implementation,
the return type isn't even deducible anymore, so it seems at least somewhat
questionable to change the design to support such a feature. For instance

template< typename T >
( ( if is_integral< T > )
  return arg + 1

as opposed to

template< typename T >
  ( if is_integral< T >)
  return arg + 1

The first one, at least to me, seems more complicated and less resembles a

It's true that "break" is one more thing to know, but making the entire
thing one macro invocation makes the original use-case -- automatically
deduced return types -- more complicated.

I could always just make a 2nd macro which puts everything into a single
invocation without requiring "break" by just implementing it in terms of my
current macro. Then I could expose them both and let users decide what they

Either way, it should be easy to implement the changed design on top of the
current design by wrapping, but not the other way around, so I think I'll
just continue on as I am now and figure things out later.

-Matt Calabrese

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