brasse
6th June 2006 20:00 UTC

Function parameters
Hello!

I have just started to use NSIS for one of my projects. In my installer script I want to use functions and I want to pass parameters to these function. As far as I can see the standard way of doing this is using the stack. If I have a function taking three parameters it will look something like this

Function GetRegValue
  Exch $R2 ; 3rd parameter, default
  Exch
  Exch $R1 ; 2nd parameter, name
  Exch
  Exch 2
  Exch $R0 ; 1st parameter, sub_key

  Push $R3 ; Save

  ReadRegStr $R3 HKLM $R0 $R1
  
  IfErrors use_default

  StrCpy $R2 $R3
  Goto end

use_default:
  ;StrCpy $R0 $R2

end:
  Pop $R3 ; Restore
  Pop $R0 ; Restore
  Pop $R1 ; Restore
  Exch $R2 ; Restore and return
FunctionEnd

All the Exch instructions to retrieve the arguments and store the values of the variables we need to use are kind of cryptic to say the least. Is this the best practice when it comes to parameters to functions in NSIS or is there a better way?

Regrads,
Mattias

CancerFace
6th June 2006 22:12 UTC

You could use a macro and pass the three parameters:

!macro GetRegValue VAR1 VAR2 VAR3
  !define Index "Line${__LINE__}"
  ClearErrors
  ReadRegStr $R3 HKLM $VAR1 $VAR2
  IfErrors ${Index}_use_default

  StrCpy ${VAR3} $R3
  Goto ${Index}_end

 ${Index}_use_default:
  StrCpy $R0 ${VAR3}

 ${Index}_end:
  !undef Index
!macroend

However I am not sure where you want the output. If the ReadRegStr fails then you copy the 3rd variable over to the 1st. However if it succeeds you copy the output to the 3rd variable (?)

In general you would call the macro like this:

!insertmacro $R0 $R1 $R2

Hope this helps ...
CF