Self-modifying forth

gistfile1.fth

: site-counter ( literal-int -- int )
    here cell - { addr }    \ store in 'addr' the address of the literal int preceding this in the user's code
    postpone dup            \ compile code to ...dup the int at the top of the data stack
    postpone 1+             \                 ...increment it
    addr postpone literal   \                 ...push the above 'addr' onto the data stack
    postpone !              \                 ...copy the incremented value INTO THE USERS CODE 
; immediate                 \ do all this at compile time

\ Now for a "normal" word defintion
: bar ( -- )
    0 site-counter          \ push zero onto the data stack and attach a counter
    100 site-counter        \ push 100 onto the data stack and attach a different counter to it
    . .                     \ print the two values on the stack
;

bar
\=> 100 0  ok

bar
\=> 101 1  ok

bar
\=> 102 2  ok