Re: Proper usage of multiple rules for the same targets

[Thomas Martitz]

Am 06.09.18 um 14:56 schrieb Paul Smith:
> On Thu, 2018-09-06 at 08:05 +0000, Tiphaine Turpin wrote:
> > The static pattern solution looks very nice, thanks. It seems to work
> > fine in the real Makefile. And there is no visible performance
> > impact, as far as I can tell (I'm not sure about how efficiently
> > static pattern rules are implemented).
> Static pattern rules are just another way of writing explicit rules.
> As such, they're more efficient than pattern rules (since they are
> applied directly when the target is needed, and no pattern matching or
> searching is necessary).


I found the thread interesting to read, I recently came across static 
pattern rules as well and like them. Since you mention efficiency, I 
wonder if there's a threshold when pattern rules become more efficient 
than tons of explicit rules (imagine explicit rules for every .o in huge 
projects). Is there a number of objects when pattern rules are 
recommended over explicit rules or are explicit rules better regardless 
of the number of them? I would imagine that pattern rules require less 
memory and that the lookup for 10000s of explicit rules becomes a 
performance issue, too.

This is a theoretical question, I haven't had performance problems with 
any type (classic, static pattern or implicit pattern rules).

Best regards.