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Rosetta Example: Object serialization

package req nx
package req nx::serializer

nx::Class create Being {
  :property {alive:boolean true}

nx::Class create Animal -superclass Being {
  :property name
  :public method print {} {
    puts "i am ${:name} alive ${:alive}"

Demonstrating the behavior in a shell:

Create a few animals

% Animal new -name "Fido"
% Animal new -name "Lupo"
% Animal new -name "Kiki" -alive false

Print the created animals

% foreach i [Animal info instances] { $i print }

The loop prints:
i am Kiki alive false
i am Lupo alive true
i am Fido alive true

Serialize the animals to a file

% set fpath [::nsf::tmpdir]/dump
% set f [open $fpath w]
% foreach i [Animal info instances] { puts $f [$i serialize] }
% close $f

Destroy all animal instances:

% foreach i [Animal info instances] { $i destroy }
% puts ===========

Print the existing animals (will print nothing)

% foreach i [Animal info instances] { $i print }
% puts ===========

Load the animals again …

% source $fpath

and print it. The print output is the same as above

% foreach i [Animal info instances] { $i print }