On 15 Feb 2017 04:47, Michael Van Canneyt <mich...@freepascal.org> wrote:
>
>
>
> On Tue, 14 Feb 2017, fredvs wrote:
>
> >> Please simply use "{$unitpath }"
> >
> > Huh, Mattias present me yesterday a beautiful "{$unitpath }".
> >
> > We played together all the night, without any trouble.
Just because things work now, doesn't mean they always will. Do you make
software to "play" and keep yourself busy, or do you want to get to business
and do something useful? If the latter option, then i think you'll want to make
sure things don't break because of wrong decisions in the past. And i believe
you'll want to keep things managable, simple and reusable. These are the
principles that form the basis for keeping configuration such as unit search
paths out of the source code.
I once restored a backup of my current project to a different directory than it
used to be in and had to fix many path references as a result. (Yes even in
sourcecode, because my project generates pascal code and calls fpc, so it also
generates a -Fu parameter and it used an absolute path because I'm stupid and
used an easy quick-fix at the time ;) ) Would you want to do that for every
source file you've got?
> > And this morning Matt said that I may not trust in {$unitpath }, that I
> > will
> > only have problems, that I should think at something else. ;-(
>
> He is correct.
And i agree. You're not talking about a bunch of shell scripts here you see.
While they are interpreted, units are compiled and some things are included
into the object file which means you'd need to recompile the unit in order to
use it in a safe, predictable and understandable way. The compiler usually
figures out which units need to be recompiled. Configuration is therefore not
something you want to put into sourcecode, as this may confuse the compiler.
This may result to it not recompiling a unit, which may lead to unpredictable
behaviour. That would mean your program does things that the source code cannot
explain. Believe me, this is hell, I've been there. (In a project about 10
years ago, a class was being rewritten from scratch. When debugging some weird
error, I noticed a variable that "magically" changed value even though it was
not assigned anywhere in the source code appart from the initialisation by the
constructor. It turned out to be an incorrect static cast to the old
class type, in a unit that was not being recompiled so the object (of the new
type) was used by that unit as if it was the old type. It cost me three days to
debug this nice little beasty and because debug info was not available, i had
to trace in assembly even. The cause? Configuration options incorrect. The unit
was implicitly linked..)
Greetz,
Tim
_______________________________________________
fpc-pascal maillist - fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
