Zarutian 4. september: Subtext [
1] is a visual programming language and environment, but that doesn't tell the whole story so follow that link to get more info.
First rough draft of possible implemention in Tcl:
- a node is a autonamed variable, possible traced
- a function is several nodes
# not tested yet
array set the_data_array {}
array set the_prog_array {}
proc get-value {identifier} {
variable the_data_array
variable the_prog_array
set from_storage [set the_prog_array($identifier)]
if {[lindex $from_storage 0] == "data"} {
return [set the_data_array($identifier)]
}
if {[lindex $from_storage 0] == "function"} {
set incoming_links [lindex $from_storage 2]
set outgoing_links [lindex $from_storage 3]
set program [lindex $from_storage 4]
# check if any incoming nodes changed:
set recaculate false
foreach link $incoming_links {
set link_identifier [lindex $link 0]
set old_value [lindex $link 1]
if {$old_value != [set the_data_array($link_identifier)]} {
set recaculate true
break
}
}
if {$recaculate} {
set vars_and_values [list]
set counter 0
foreach link $incoming_links {
set link_identifier [lindex $link 0]
lappend vars_and_values "input[incr counter]"
lappend vars_and_values [set the_data_array($link_identifier)]
}
array_multiset [eval_with [set the_data_array($program)] $vars_and_values] the_data_array $outgoing_links
}
}
}
proc array_multiset {values arrayname indexes} {
# this proc returns nothing but has write sideeffects on the array $arrayname
upvar $arrayname thearray
#checking that arrayname is indeed an array
if {![array exists thearray]} {
error "arrayname must refer to an array"
}
set value_index 0
set value_index_max [llength $values]
foreach index $indexes {
set thearray($index) [lindex $values $value_index]
}
}
proc eval_with {script vars_and_values} {
multiset $vars_and_values
# to prevent possible security hole
# the script below reffers to the first
# parameter of the procedure with [lindex [info level 0] 1]
# instead of $script because script might been set in
# the muliset call
return [eval [lindex [info level 0] 1]]
}
proc multiset {vars_and_values} {
foreach {var value} {
upvar $var tmp
set $tmp $value
}
}
