Ruby class object

Intro of ruby class data structure

Transcript

1. Ruby Something about object and class Thursday, 3 May, 12
2. Keywords @ @@ iv_tbl klass super module m_tbl class self Thursday, 3 May, 12
3. Revisit OO what is classes? It is just an ADT(Abstract Data T ypes) http://www.youtube.com/watch? v=GDVAHA0oyJU Thursday, 3 May, 12
4. Class A Oject super klass klass klass Simple Class Thursday, 3 May, 12
5. Method Lookup 1. follow receiver’s klass pointer the search the m_tbl 2. follow super pointer and search the m_tbl 3. Repeat 1,2 4. invoke method_missing on original receiver, and go though 1-3 again. Thursday, 3 May, 12
6. A Oject super Mixin Minix Super klass objA klass Module Thursday, 3 May, 12
7. module A def hello :helloA end end module B include A def hello :helloB end end module C include A def hello :helloC end end class D include C include B end D.new.hello Thursday, 3 May, 12
8. D super B B klass objectD klass C C super klass A A A super klass klass super Modules Thursday, 3 May, 12
9. @ @@ Both @ and @@ are value stored at `iv_tbl` instance_variable_get class_variable_get class A @var = :classinst def initialize @var = :inst @@var = :class end def ivar @var end def cvar @@var end end a = A.new a.ivar a.cvar a.var A.instance_variable_get(:@var) a.instance_variable_get(:@var) a.instance_variable_get(:@@var) a.class_variable_get(:@var) a.class_variable_get(:@@var) http://rhg.rubyforge.org/chapter06.html Thursday, 3 May, 12
10. @@ often have real use @@ Will dependent on the inheritance hierarchy class A @@x = 3 end class B < A @@x = 4 end A.class_variable_get(:@@x) Thursday, 3 May, 12