recursing ddoc macros two arguments at a time

[Walter Bright via Digitalmars-d]

On 1/16/2015 4:11 PM, Andrei Alexandrescu wrote:
> I thought this isn't possible: http://goo.gl/QTAUFb. This:
>
> $(TOCENTRY comparison.html, D Feature List)
> $(TOCENTRY builtin.html,    Rationale for Builtins)
> $(TOCENTRY ctod.html,       Converting C to D)
> $(TOCENTRY cpptod.html,     Converting C++ to D)
> $(TOCENTRY pretod.html, The C Preprocessor vs D)
> $(TOCENTRY cppcontracts.html,     D Contract Programming vs C++)
>
> can be simplified to this:
>
> $(TOCENTRIES
>          comparison,   D Feature List,
>          builtin,      Rationale for Builtins,
>          ctod,         Converting C to D,
>          cpptod,       Converting C++ to D,
>          pretod,       The C Preprocessor vs D,
>          cppcontracts, D Contract Programming vs C++
> )
>
> (The .html elimination is a minor detail.)
>
> The trick is to recurse twice using $+ every time:
>
> TOCENTRIES=$(TOCENTRY $1, $2) $(TOCENTRIES_REC $+)
> TOCENTRIES_REC=$(TOCENTRIES $+)
>
> Thought this is worth sharing. We could simplify a few more things with this.

Two thoughts:

1. Need to add this to the Ddoc documentation! Or at least a tip sheet on Ddoc.

2. Why use url shorteners like http://goo.gl/QTAUFb ? I don't generally care to 
click on links that I have no idea where they go. Here's the real link:

https://github.com/D-Programming-Language/dlang.org/pull/776/files#diff-582d0a2140b180aec5d08a9e6176399aR71