Use of labels in PB/DLL

[Bern Ertl]

I would just like a clarification on the scoping rules for labels.

It appears that labels are local to SUBs/FUNCTIONs as long as they
are referenced via GOTO/GOSUB, but global when referenced via
assembly jump instructions.

I've had to make all labels referenced via my inline assembler
routines unique while labels referenced via PB/DLL statements
are not (necessarily) unique.

I didn't see any explanation for using unique labels with ASM
instructions in the manual...



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Bernard Ertl

[Cecil Williams]

Bern,

One could alleviate this problem by not using labels in the
high level programming portions of your modules. I know you
probably don't want to hear it but all high level programming
languages discourage this practice. I used to do the label
gig a long time ago, but no longer.

Assembler, on the other hand, it's a necessary evil. However,
it's usually easier to follow in asm notation than standard
Basic or C/C++ or whatever coding.

Personally, nothing is more irritating than trying to follow
labels stuck all over the place. Give me procedures (subs
or functions)any day. Just a programming preference!!!!

Cheers,
Cecil

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[Peter Scheutz]

Originally posted by Bern Ertl:
I would just like a clarification on the scoping rules for labels.

It appears that labels are local to SUBs/FUNCTIONs as long as they
are referenced via GOTO/GOSUB, but global when referenced via
assembly jump instructions.

I can confirm you observation. Found out the hard way too..

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Best Regards
Peter Scheutz

[Lance Edmonds]

R&D advise that in the next update to the compiler, labels will be 100% local in scope, even to inline assembler code. It would not be wise to exploit the current ability unless you don't want to be able to recompile in the future.

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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Steve Hutchesson]

Bern,

Using unique labels is still a necessity in this version as most
of us have found out but Lance mentioned that later versions will
make labels local to each procedure which in most instances will
make label usage easier to manage.

I know where Cecil is coming from as I have seen some really badly
written code that had badly named labels all over the place. Problem
is that there are many tricks in speed terms, even in high level
language where exiting a loop with a GOTO is just more efficient
so I am inclined to use long label names so I know what they are
for.

Your worst nightmare is a multi level deep loop with labels like
X: Y: etc.. which are non referential.

I prefer labels named like Loop_Start: Loop_Exit: so that you
can use code like

If [condition] Then GOTO Loop_Exit

and you don't get the problem of unintelligible locations.

Regards,

[email protected]

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[Bern Ertl]

Everyone,

Thanks for the clarification.

I too prefer not to use labels, but sometimes it is necessary.




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Bernard Ertl