simen.kjaras at gmail.com
Tue Jan 25 07:33:06 PST 2011
spir <denis.spir at gmail.com> wrote:
> 1. Is the fact that we have so many ways to define the same thing a Good
> Thing, according to you?
> 2. What is the reason for Phobos defining param funcs as template
> params? Efficiency? Why?
Efficiency is one reason, as DMD is unable to inline functions passed as
parameters. It is also a kind of currying, allowing one to define the
function as foo!bar, and for instance store it in an alias.
> 3. What is the meaning of 'alias f'? How does it work? This is a totally
> enigmatic feature for me. Seems it allows placing anything of any type
> as template param. Far more versatile than common use of templates as
> 'simple' generics. Note that if I remove the seemingly useless 'alias'
> from version 1 , I get:
> Error: template instance hof1!(int,f) does not match template
> declaration hof1(P,f)
> (could not find any explanation on alias params anywhere -- pointers
> also welcome)
D templates take three kinds of parameters - types, aliases, and values.
While the other two are easy to understand, aliases are somewhat more
complex. In short, an alias can reference anything that has a name. The
details may be more complex, but that's the gist of it.
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