Re: %{expand:...} documentation

[Jeff Johnson <n3npq jbj gmail com>]

On Aug 27, 2007, at 2:26 PM, Jos Vos wrote:

> Hi,
>
> Where can I find documentation about how %{expand:...} exactly is
> defined and when it is useful?

The macro primitive %{expand:...} is like eval in shell.

All it does is continue a macro expansion from the beginning, not
the end, of whatever was justr expanded.

So if, say, you wanted to define
   %define foo	bing
    %define %{foo} bang
to have the result be
    %bing bang
then this construct accomplishes
%{expand:%%define %{foo} bang}

The 1st pass substitutes "bing" for %{foo}, the second pass
accomplishes the define.

> When browsing through spec files, I have the impression that it is
> unnecessarily used in a lot of cases.

Likely.

73 de Jeff