No way... FASM doesn't have arbitrary-length compile-time variables. There was a discussion on this limitation long time ago.

var = 'abc'    

var: 'abc'    

Code:

var: 'abc'    

It's just a pointer to the offset of 'a'.

var: db 'abc'    

push var
call [someLoaderAPI]
    

macro load_array var,src,n
 {
        rept n i:0
        \{
                match j,i
                \\{
                        load var\\#j byte from src+i
                \\}
        \}

        match i,n \{ var#_length equ i \}
 }

macro store_array var
 {
        n equ var#_length

        rept n i:0
        \{
                match j,i
                \\{
                        db var\\#j
                \\}
        \}
 }


dinp db 'my example data.'
;            ^
;          dinp+4

load_array myVar,dinp+4,5
; myVar0 = 'x'
;      1 = 'a'
;      2 = 'm'
;      3 = 'p'
;      4 = 'l'
; myVar_length = 5


gap db 'myVar = '

dout:
    db '0'+myVar_length,':'
store_array myVar
; This should print:
; myVar = 5:xampl