Re: [boost] metactrl header [compile time asserts]

From: David Abrahams (abrahams_at_[hidden])
Date: 2000-07-23 16:28:49

The template mechanism is equivalent to a functional programming language.
What is this construct called in Lisp? Ugh, I think it's called 'if'.

What is the ?: operator called in C/C++?

BTW, I attended a Generic Programming conference with C&E in '98
http://www.cs.rpi.edu/~musser/gp/dagstuhl/gpdag.html where they talked about
generative programming. Most of it seemed to be a pile of buzzwords and
excitement with little to back it up, but they did present a complete lisp
interpreter implemented at compile-time with C++ templates!

----- Original Message -----
From: "Greg Colvin" <greg_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Sunday, July 23, 2000 4:42 PM
Subject: Re: [boost] metactrl header [compile time asserts]

> From: David Abrahams <abrahams_at_[hidden]>
> > I totally support all of Howard's arguments below :)
>
> Me too.  But what names to use?  Howard's names for 'IF'
> don't make it so clear what the meaning of the parameters
> is.  Maybe 'If' would do?
>
> Or if we are feeling very brave, how about something like
>    #define If whatever<
>    #define Then ,
>    #define Else ,
>    #define End >::type
> so that instead of the inscrutable
>    typedef If<flag, type1, type2>::type my_type;
> we can write
>    typedef
>       If flag Then
>          type1
>       Else
>          type2
>       End
>    my_type;
>
> And Howard thought he was getting punchy!
>
>
>
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