[phobos] expand for std.metastrings

[Robert Jacques]

On Tue, 02 Nov 2010 16:08:11 -0400, kenji hara <k.hara.pg at gmail.com> wrote:
> The points of text vs expand are:
> - text is comma separated formatting, expand is inlined formatting.

Personally, I consider comma separated formatting to be inlined, or at  
least inline style, but I understand your point.

> - text is general formatting function, expand is mostly useful in
> compile-time, and specialized D code formatting for code generation.

And text is both general and works at compile time.

> - editor highlighting issue - my editor does not color q{}, so
> generating code are colored with normal syntax highlighting. If I use
> text and its formatting, code readability will be wrong. I don't like
> it.

I think this is the biggest advantage of it. Well, that and familiarity to  
Perl, PHP, etc, users.
But the amount/size of code inside these strings need to be pretty large  
before it gets really annoying. For me, your generateFun example (which is  
the only use of expand in interfaces.d) is a two liner, and is simply not  
big enough to start sweating about these issues to me. And most of my  
large mixins for me are generated dynamically; my need for expanding  
variables in long strings is pretty minimal. You wouldn't have/know of a  
good example of a long explicit string mixin requiring non-trivial  
expansion, would you?

I recognize the benefits of expand, but I'm just concerned about  
introducing yet-another string formating routine, particularly one that  
looks low-yield in terms of power and is rather complex, into phobos.

Part of this problem could be addressed with better documentation, which  
highlights the shell-like syntax and the differences between expand, text,  
Format and ~.