Re: Preferred style of use-clauses

[vilot@wanginst.UUCP (Michael Vilot)]

In article <2938@sdcrdcf.UUCP> lwall@sdcrdcf.UUCP (Larry Wall) writes:
>
>If you are in a situation where the types of your subprogram arguments are
>clear, and your abstract types are all nicely confined to packages so that
>you don't rely on hiding mechanisms of dubious value, I see no reason to
>avoid the use of multiple USE clauses, even in large projects, even where
>it results in overloading.  

Consider  one more reason to  have USE  clauses:  changing a package's
imported environment  explicitly.  Suppose   you  have  built a   test
version of a system which instruments some features you are interested
in.  Now,  suppose you have  to get the  same  system into "production
shape" (i.e. faster and/or smaller), and you're not  interested in the
instrumentation.  It may be far easier to go from:

with Heavily_Instrumented_Package; use Heavily_Instrumented_Package;
procedure The_System is
begin
	Do_Interesting_Stuff;
end;

	... to:

with Simpler_and_Faster_Package; use Simpler_and_Faster_Package;
procedure The_System is
begin
	Do_Interesting_Stuff;
end;

	... than to replace all occurrences of the fully qualified
names.

	Of course, in a well-run project, the need for two versions is
all seen in advance, and the change should "never be needed" :-)