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rosetta-delegates.html
Listing of doc/example-scripts/rosetta-delegates.tcl
Rosetta Example: Delegates
For details see https://rosettacode.org/wiki/Delegates
package req nx nx::Class create Delegator { # The class Delegator has a property named "delegatee" which is an # object: :property delegatee:object # The method "operation" decides, whether it deletates the action to # another object, or it performs the action itself. :public method operation {} { if {[info exists :delegatee]} { ${:delegatee} operation } else { return "default implementatiton" } } } nx::Class create Delegatee { # The class "Delgatee" might receice invocations from the class # "Delegator" :public method operation {} { return "delegatee implementatiton" } }
Demonstrating the behavior in a shell:
Create a Delegator
, which has no delegatee
defined. Therefore
delegator performs the action by itself, the default implementation.
% set a [Delegator new] % $a operation default implementatiton
Now, we set the delegatee
; therefore, the delegatee will perform
the action.
% $a configure -delegatee [Delegatee new] % $a operation delegatee implementatiton