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Defined(Label, #PB_Label) problem ?
Posted: Tue Jan 15, 2019 12:58 pm
by benmalartre
Here is the problem I'm facing:
I want to check the existence of a label when creating an object
while the label is defined inside the module itself, it is not inside a procedure of the module
(in fact it is , I can assign it with ?Label, but the function Defined(Label, #PB_Label) says it's not)
I tested on both Windows and MacOS with the same result
here is some test code:
Code: Select all
DeclareModule Object
Declare Test()
DataSection
ObjectVT:
EndDataSection
Macro INI(obj)
CompilerIf Defined(obj#VT, #PB_Label)
Debug "LABEL FOUND"
CompilerElse
Debug "LABEL NOT FOUND"
CompilerEndIf
EndMacro
EndDeclareModule
Module Object
INI(Object)
Debug ?ObjectVT
Procedure Test()
INI(Object)
Debug ?ObjectVT
EndProcedure
EndModule
Object::Test()
which says:
LABEL FOUND
5368956240
LABEL NOT FOUND
5368956240
Is it a bug or normal behavior?
Re: Defined(Label, #PB_Label) problem ?
Posted: Tue Jan 15, 2019 1:07 pm
by NicTheQuick
It is possible to define local and global labels. In fact each defined label lives in the scope of a procedure, a module or even global. Maybe there is some weirdness going on with the Defined() command here.
Because it is not possible to use Goto with a global label inside of a procedure, it should also not be possible to use ?label inside a procedure. But in fact it is possible. Without this possibility a lot of OOP like modules out there would not work anymore.
Code: Select all
Goto error
Debug "1 never"
error:
Debug "1 always " + StrU(?error, #PB_Quad)
Procedure a()
Goto error
Debug "2 never"
error:
Debug "2 always " + StrU(?error, #PB_Quad)
EndProcedure
Procedure b()
Goto error
Debug "3 never"
error:
Debug "3 always " + StrU(?error, #PB_Quad)
EndProcedure
Procedure c()
Debug "4 what? " + StrU(?error, #PB_Quad)
EndProcedure
a()
b()
c()
Re: Defined(Label, #PB_Label) problem ?
Posted: Tue Jan 15, 2019 1:12 pm
by STARGÅTE
It seems like it's a problem in Procedures:
Code: Select all
Procedure Test()
Debug Defined(Test, #PB_Label)
Debug ?Test
DataSection
Test:
EndDataSection
EndProcedure
Test()
Re: Defined(Label, #PB_Label) problem ?
Posted: Tue Jan 15, 2019 6:03 pm
by Little John
Original code simplified (still doesn't work as expected (with PB 5.70 on Windows 10)):
Code: Select all
DataSection
ObjectVT:
EndDataSection
Debug Defined(ObjectVT, #PB_Label)
Debug ?ObjectVT
Procedure Test()
Debug Defined(ObjectVT, #PB_Label)
Debug ?ObjectVT
EndProcedure
Test()
Since
works properly outside and inside the procedure, but
only works properly outside the procedure, I think it's a bug with Defined() in Procedures.
If the label were not visible inside the procedure, then using
inside the procedure would raise an error.
Re: Defined(Label, #PB_Label) problem ?
Posted: Tue Jan 15, 2019 8:10 pm
by Josh
Defined only returns #True if the label was defined in the same scope and before the Defined command. This is all correct.
Since version 5.10 labels are local. I think it was a compromise to get the address of a label outside the scope to keep old code executable. Maybe it would have been enough if labels in a DataSection were global, but I don't see any problem, as it is now.
Re: Defined(Label, #PB_Label) problem ?
Posted: Tue Jan 15, 2019 8:30 pm
by benmalartre
Thanks all to have a look
I avoid the problem by declaring empty labels and not use Defined(Label, #PB_Label) inside of my procs
Re: Defined(Label, #PB_Label) problem ?
Posted: Wed Jan 16, 2019 8:05 pm
by NicTheQuick
I think Defined behaves from the same perspective as Goto would see the label.
Re: Defined(Label, #PB_Label) problem ?
Posted: Wed Jan 16, 2019 8:26 pm
by Josh
NicTheQuick wrote:I think Defined behaves from the same perspective as Goto would see the label.
No.
Goto can be placed before the label,
Defined would return a #False at the same position.