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Macro concatenate doesn't work with variable?
Posted: Sat May 04, 2024 2:15 am
by BarryG
I was looking at this topic ->
https://www.purebasic.fr/english/viewtopic.php?t=84189
And I wanted to try and help, but this test code doesn't work if I use a variable ("n") instead of a literal number like "1".
I assumed the macro would take the numeric value of "n" to concatenate it to the "MyLabel_" text? But it's just literally using the text "n" instead?
Code: Select all
Macro DynamicRestore(n)
MyLabel_#n
EndMacro
n=Random(3,1)
Restore DynamicRestore(1) ; Change "1" to "n" and it doesn't work?
Read.s label$
Debug label$
End
DataSection
MyLabel_1: : Data.s "MyLabel_1"
MyLabel_2: : Data.s "MyLabel_2"
MyLabel_3: : Data.s "MyLabel_3"
EndDataSection
The reason for my confusion is because in this example, the macro
IS using the numeric value of "n" to double it:
Code: Select all
Macro test(n)
n*2
EndMacro
n=50
Debug test(n) ; Outputs 100
So, what the?
Re: Macro concatenate doesn't work with variable?
Posted: Sat May 04, 2024 7:41 am
by Demivec
The macro functions by substituting the 'text' of its parameters at compile time. The text of the parameters is not interpreted in the macro but instead is interpreted by the compiler after the macro substitution occurs in the source code. The concatenation symbol '#' concatenates the text of the macro parameter with the adjacent text in the source of the macro, again before compiling and not at run time.
In the second code sample you posted the macro parameter is n and its substitution text is 'n'. So Debug test(n) is compiled as Debug n*2. At run time n=50 and the displayed result is 100.
Re: Macro concatenate doesn't work with variable?
Posted: Sat May 04, 2024 7:50 am
by Michael Vogel
Code: Select all
Macro DynamicRestore(n)
MyLabel_#n
EndMacro
n=2
Restore DynamicRestore(n)
Read.s label$
Debug label$
; ---------------------------------------------------------------------------------------
Global Dim Labels(3)
Labels(1)=?MyLabel_1
Labels(2)=?MyLabel_2
Labels(3)=?MyLabel_3
Procedure RestoreEx (*address)
CompilerIf (#PB_Compiler_Processor = #PB_Processor_x86)
!mov eax, [p.p_address]
!mov [PB_DataPointer], eax
CompilerElse
!mov rax, [p.p_address]
!mov [PB_DataPointer], rax
CompilerEndIf
EndProcedure
RestoreEx(Labels(n))
Read.s label$
Debug label$
End
DataSection
MyLabel_1: : Data.s "MyLabel_1"
MyLabel_2: : Data.s "MyLabel_2"
MyLabel_3: : Data.s "MyLabel_3"
MyLabel_n: : Data.s "MyLabel_NNNNN"
EndDataSection
Re: Macro concatenate doesn't work with variable?
Posted: Sat May 04, 2024 8:40 am
by juergenkulow
After adding MyLabel_n: in DataSection the preprocessor "-pp /tmp/a.pp" do Restore MyLabel_n:
Code: Select all
Macro DynamicRestore(n)
MyLabel_#n
EndMacro
n=Random(3,1)
Restore MyLabel_n
Read.s label$
Debug label$
End
DataSection
MyLabel_n:
MyLabel_1:
Data.s "MyLabel_1"
MyLabel_2:
Data.s "MyLabel_2"
MyLabel_3:
Data.s "MyLabel_3"
EndDataSection