datadef@directives equ db,dw,du,dd,dp,dq,dt
datarsv@directives equ rb,rw,rd,rp,rq,rt
def.rb equ db
def.rw equ dw
def.rd equ dd
def.rp equ dp
def.rq equ dq
def.rt equ dt
;==============================================================
macro set var,value {var equ value }
;==============================================================
macro virtual@overridedefs [datadef] {
        struc datadef [val:?] \{ \common
                        \local ..anonimous
                        ..anonimous datadef val
                        match any,@virtbase \\{ define . ..anonimous + any \\} \} }
;==============================================================
macro virtual@overridersvs [datadef] {
        match ddd,def.#datadef \{
        struc datadef count \\{ \\common
                        \\local ..anonimous
                        ..anonimous ddd count dup (?)
                        match any,@virtbase \\\{ define . ..anonimous + any \\\} \\} \} }
;==============================================================
macro virtual@restoredefs [datadef] { restruc datadef }
;==============================================================
macro extendvirtual {
        macro virtual statement& \{
                match ,statement \\{
                        \\local ..anonimous
                        label ..anonimous
                        @virtbase equ ..anonimous \\}
                match =at base,statement \\{
                        @virtbase equ base \\}

                match any,datadef@directives \\{ virtual@overridedefs any \\}
                match any,datarsv@directives \\{ virtual@overridersvs any \\}
                virtual at 0 \}
        macro endv \{
                virtual@restoredefs datadef@directives,datarsv@directives
                restore @virtbase
                end virtual \} }
@virtbase equ
; use case: ========================
extendvirtual
virtual at 0+fixer
        a dd ?
        b db 6
endv; end virtual

use32
fixer = 5
mov eax,[a] ;a is 5, and dword size specifier stored in a
display 'a=',a+'0',13,10,'b=',b+'0',13,10; must show a=5,b=9

fixer = 3
mov al,[b]  ;b is 7, and byte size specifier stored in b
display 'a=',a+'0',13,10,'b=',b+'0'; must show a=3,b=7