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#
# == Rosetta example: Add a variable to a class instance at run time
#
# Demonstrate how to dynamically add variables to an object (a class instance) at run time.
# https://rosettacode.org/wiki/Add_a_variable_to_a_class_instance_at_runtime#Tcl
#
package req nx
package req nx::test
#
# The class +Empty+ does not provide any structural or behavioral
# features on behalf of future instances, they will remain empty.
#
nx::Class create Empty
#
# Provide one instance of +Empty+ to add an object variable to ...
#
Empty create ::e
# Is +e+ truly empty?
? {::e info vars} ""
#
# NX offers different types of object-variable managers: properties,
# variable slots, and plain Tcl per-object variables. Below, we
# showcase variable slots (although the others can be added
# dynamically alike).
#
# a) Declare a variable slot +foo+; +-accessor+ will provide
# getter/setter methods for this one object +e+ automatically.
::e object variable -accessor public foo
# b) Define a value for the variable slot +foo+
? {::e foo set 1} 1
# c) Is there a Tcl variable managed by the variable slot?
? {::e info vars} "foo"
# d) Retrieve +foo+'s value
? {::e foo get} 1
#
# A second instance of +Empty+ has no such capability: +foo+
#
Empty create ::f
# a) Is there any Tcl variable, one named +foo+? No ...
? {::f info vars} ""
# b) Are there getter/setter methods for a +foo+? No ...
? {::f foo set} "::f: unable to dispatch method 'foo'"
# c) Is there a variable slot +foo+? No ...
? {::f info object variables foo} ""
#
# In NX, once dynamically added, a variable slot can also be dynamically removed again.
#
::e delete object variable foo
# a) Is the variable slot +foo+ gone? Yes ...
? {::e info object variables foo} ""
# b) Is the Tcl variable gone? Yes ...
? {::e info vars} {}
# c) Are the getter/setter methods gone? Yes ...
? {::e foo get} "::e: unable to dispatch method 'foo'"
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