Any var-type return for Functions

[Psychophanta]

Currently, procedures can return only PB internal native variable types, but it is more and more necessary to allow to return any variable type.
Sorry if this suggest was post in the past, but i don't find.

[Dräc]

[refresh ]
Is using structure has ProcedureReturn planned for an immediate future of the PB version? (and available for Interface also...)

[Kaeru Gaman]

no.
Structures are always passed byRef.
that means you pass the pointer of a structure to be filled to the Procedure.
the Return Value can also be a pointer to a structure.

the Return Value of a Procedure is at max a Quad.
sure you can put this Quad into a StructureUnion.

Code: Select all

Structure DoubleCoord
  C1.COORD
  C2.COORD
EndStructure

Structure Passer
  StructureUnion
    StrP.DoubleCoord
    QuaP.q
  EndStructureUnion 
EndStructure

Procedure.q GetCoords( X.w, Y.w )
  Protected OutCoords.Passer        ; define an internal Passer
  OutCoords\StrP\C1\x = X + 100       ; fill the structured Part
  OutCoords\StrP\C1\y = Y - 100
  OutCoords\StrP\C2\x = X - 100
  OutCoords\StrP\C2\y = Y + 100
  ProcedureReturn OutCoords\QuaP    ; return the quad Part
EndProcedure

Define TestCoords.Passer

TestCoords\QuaP = GetCoords( 200, 500 )         ; fetch a quad

Debug "C1\x = " + Str( TestCoords\StrP\C1\x )   ; debug the structured content
Debug "C1\y = " + Str( TestCoords\StrP\C1\y )
Debug "C2\x = " + Str( TestCoords\StrP\C2\x )
Debug "C2\y = " + Str( TestCoords\StrP\C2\y )

but this is rather unusual, and only possible for structures that cover maximum 64bit.

[Dräc]

Oh! I was’nt aware that you are on the PB development team, Kaeru Gaman

[netmaestro]

Note though that if you want to ProcedureReturn a pointer to a structure and have all members of the structure available to the caller you must use AllocateMemory or a persistent scope like global or the memory is freed on exit.

[Kaeru Gaman]

Oh! I was’nt aware that you are on the PB development team, Kaeru Gaman

..no need to be on the team to answer this, because we just had a discussion about this lately,
and Freak himself stated that it is not at all planned to change the returning from how it is now.

the ReturnValue is in EAX for Long or smaller, for Quad or Double there is one additional Register used.
Freak said, they are not thinking about changing this way.

[Dräc]

Ok! Thx Kaeru Gaman!