# FIXME: easier to use tasks + shallow binding constructs

# some convenient words to fake objects/closures using variables and
# lists

# there are no true dynamic closures in pf for the simple reason that
# it's hard to do correctly dynamically without a garbage collector.

# the idea is this: object state is saved in a list. methods action on
# an object will set the current state to a couple of global
# variables, which will be restored back after we're done. please note
# that this is not re-entrant, and is really only good for emulating
# closures (objects with a single method 'doit'), not objects with
# methods that call each other.

# the syntax is:
# <list of variable symbols> context <enter-word> <leave-word>
# (x y) context [[[ ]]]
# : doit [[[ x @ y @ + x ! ]]] ;

: enter-context    >r unpack r> { execute ! } for-each ;
: leave-context    list:size >r { execute @ } for-each r> pack ;


: link-context 
     >r >r >r
     r  { undef swap link-variable! } for-each	# create variables
     r> ' find map				# get list of XTs
     dup reverse swap				# leave uses the reversed list
     ' enter-context r> link-curried
     ' leave-context r> link-curried ;

"( list enter leave -- )\tCreate context load/save words for variables contained in list." doc


: context read read link-context ;