【デザインパターン】RubyのComposite

code:ruby

irb(main):105:0> tree.add(branch1)

=>

@children=

[#<Composite:0x0000000100a72870

@children=

[#<Leaf:0x0000000100c555e8 @parent=#<Composite:0x0000000100a72870 ...>>,

@parent=#<Composite:0x0000000100b405e0 ...>>]>

irb(main):106:0> tree.add(branch2)

=>

@children=

[#<Composite:0x0000000100a72870

@children=

[#<Leaf:0x0000000100c555e8 @parent=#<Composite:0x0000000100a72870 ...>>,

@parent=#<Composite:0x0000000100b405e0 ...>>,

@parent=#<Composite:0x0000000100b405e0 ...>>]>

・末端は必ずleaf、子のあるオブジェクトはCompositeになる

code:ruby

irb(main):110:0> branch3 = Composite.new

irb(main):111:0> branch3.add(Leaf.new)

=>

irb(main):112:0> branch1.add(branch3)

=>

@children=

[#<Leaf:0x0000000100c555e8 @parent=#<Composite:0x0000000100a72870 ...>>,

@parent=#<Composite:0x0000000100a72870 ...>>],

@parent=

@children=

[#<Composite:0x0000000100a72870 ...>,

@parent=#<Composite:0x0000000100b405e0 ...>>,

irb(main):113:0> client_code(tree)

RESULT: Branch(Branch(Leaf+Leaf+Branch(Leaf))+Branch(Leaf)+Leaf)

・最初同じ階層のものは同じオブジェクトになるかと思ったけど上記の例は違う

・Componentのオブジェクトに対してはaddとかremoveとかできない

code:markdown

tree (root)

├── branch1

│ ├── Leaf (最初からあった)

│ ├── Leaf (最初からあった)

│ └── branch3 (新しく追加)

│ └── Leaf

├── branch2

│ └── Leaf

└── Leaf (rootの直下)