浅拷贝:
a = [1, 2, 3, 4]
b = a
a << 5
pp a, b
#=> [1, 2, 3, 4, 5]
#=> [1, 2, 3, 4, 5]
深拷贝:
a = [1, 2, 3, 4]
b = a.dup
a << 5
pp a, b
#=> [1, 2, 3, 4, 5]
#=> [1, 2, 3, 4]
浅拷贝:
a = [1, 2, 3, 4]
b = a
a << 5
pp a, b
#=> [1, 2, 3, 4, 5]
#=> [1, 2, 3, 4, 5]
深拷贝:
a = [1, 2, 3, 4]
b = a.dup
a << 5
pp a, b
#=> [1, 2, 3, 4, 5]
#=> [1, 2, 3, 4]