The MASM Forum Archive 2004 to 2012

Hello!

This is my simple problem: I've tried to declare a structure like this
MyObject     STRUCT
        Function1        PROC      :DWORD
        Function2        PROC      :DWORD
        Function3        PROC      :DWORD
MyObject      ENDS

and, then, to call a function like this

push 10h
call    dword ptr [eax+MyObject.Function1]

Now this doesn't work. It only works if I rreplace PROTO definitions with DWORD's.
I would like to know why, and where can you use that kind of structure?

Thanks,
Nick

Nick,

Structures and unions are data structures where a prototype is a type checking mechanism for invoke calls, they are not the same animal.

Hi, hutch
:bg

Ok, but where can be used this structure? I've tried to use it like this, but this is not the way...

ProcedureStr   STRUCT
   Function1      PROTO   :DWORD
ProcedureStr   ENDS

ProcedureStr.Function1      PROC  A_Argument:DWORD
mov eax, A_Argument
ret
ProcedureStr.Function1      ENDP


.
.
.
INVOKE ProcedureStr.Function1, 100h

Nick

I've came to this when I was thinking about a macro for calls to COM objects. I thought that I could do something like this:
OBJStructure  STRUCT
    Function1   PROTO :DWORD, DWORD
    Function2   PROTO :DWORD
OBJStructure  ENDS

.DATA
PointerToObj   OBJStructure ptr   0

.CODE
MyMacro   PointerToObj.Function1, Arg1, Arg2

and, within MyMacro to do a typecheck like INVOKE does, using PROTO in that structure, and, if everything is OK, to do something like this in the end:
call dword ptr [eax+OBJStructure.Function1]
But I'm stuck with this problem.
I found a way arround that seem to work till now:
OBJStructure  STRUCT
  union
    Function1   PROTO :DWORD, DWORD
    Function1_   DWORD   ?
  ends
  union
    Function2   PROTO :DWORD, DWORD
    Function2_   DWORD   ?
  ends
OBJStructure  ENDS

but this is ugly... :)
I was hoping that there is a way to know - within macro - at wich offset form the start of a structure is the proto the caller needs.

here are my iFunc/iFuncVar macros. In the .inc file there are examples of their usage.

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Hello, Ultrano! Thanks for that!
But I was thinking that all this can be done in a standard way, using PROTO. As I said earlier, I've found a way to use that structure, but I can't get the PROTO within it, so I can't compare arguments against the proto.... I better attach an example:

Nick

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Hello,
Why don't use :

Quote
pcomethod1      TYPEDEF PROTO :DWORD
comethod1           TYPEDEF PTR pcomethod1


  STIPersistFile            STRUCT DWORD
   ;   Iunknown commune a toutes les interfaces
      Fonction       comethod1       ?
          //
STIPersistFile            ENDS

                       ToutEnMasm

               

Hi!
Thanks for reply! But will I be able to follow back a symbol till his PROTO (suposing that I have lots of structures and objects, so I have to rely on that symbol name, as in zip file)?
No doubt, neither my method can follow back, and this looks better.

Ok, I will post thisquestion, even if it sound silly:
Why you can put PROTO in a STRUCT, if you can't retive a offset from the begining of that structure?

Nick

Hello,
For the addres of the structure , there is two cases.
***** For interfaces , the adress is given by an API
***** FOR prototypes in the source code,create a data in .data (must be initialised data,not .data?)
       
sample

MYPROGS STRUCT
        first method3 ?
MYPROGS ENDS

.data
     myprogs MYPROGS <>
.code
     lea ebx,myprogs            ;and you have the pointer on the structure usable with invoke
     


I see thet, ToutEnMasm , merci for reply!
In fact, I was interested in that because of COM objects, and this won't help there, science there is no point in creating a structure in .DATA, .DATA? or .CONST section.

Best regards,
Nick