RosettaCodeData/Task/Add-a-variable-to-a-class-i.../Icon/add-a-variable-to-a-class-i...

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link ximage
procedure main()
c1 := foo(1,2) # instance of foo
write("c1:\n",ximage(c1))
c1 := extend(c1,["c","d"],[8,9]) # 2 new fields
write("new c1:\n",ximage(c1))
c1 := extend(c1,["e"],[7]) # 1 more
write("newest c1:\n",ximage(c1))
end
class foo(a,b) # dummy class
end
procedure extend(instance,newvars,newvals) #: extend a class instance
every put(f := [],fieldnames(instance)) # copy existing fieldnames
c := ["tempconstructor"] ||| f # new constructor
every put(c,!newvars) # append new vars
t := constructor!c # new constructor
x := t() # new instance
every x[v := !f] := instance[v] # same as old instance
x.__s := x # new self
if \newvals then
every i := 1 to min(*newvars,*newvals) do
x[newvars[i]] := newvals[i] # add new vars = values
return x
end