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author | greybird <greybird91@gmail.com> | 2013-08-07 11:20:20 +0400 |
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committer | greybird <greybird91@gmail.com> | 2013-08-07 11:20:20 +0400 |
commit | 80c71ef1c849d4294e13c3dbfce6fad66a79e99a (patch) | |
tree | ed4510ea7b68d0b8e0a043de64dac1ffd71243d6 /ruby.html.markdown | |
parent | f5023cc9b35be5d1986a76ce1d6f44979a766afb (diff) |
Ruby. Difference between class instance variables and class variables
Diffstat (limited to 'ruby.html.markdown')
-rw-r--r-- | ruby.html.markdown | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/ruby.html.markdown b/ruby.html.markdown index a3bcbbd5..99817982 100644 --- a/ruby.html.markdown +++ b/ruby.html.markdown @@ -325,4 +325,50 @@ dwight.name #=> "Dwight K. Schrute" # Call the class method Human.say("Hi") #=> "Hi" +# Class also is object in ruby. So class can have instance variables. +# Class variable is shared among the class and all of its descendants. + +# base class +class Human + @@foo = 0 + + def self.foo + @@foo + end + + def self.foo=(value) + @@foo = value + end +end + +# derived class +class Worker < Human +end + +Human.foo # 0 +Worker.foo # 0 + +Human.foo = 2 # 2 +Worker.foo # 2 + +# Class instance variable is not shared by the class's descendants. + +class Human + @bar = 0 + + def self.bar + @bar + end + + def self.bar=(value) + @bar = value + end +end + +class Doctor < Human +end + +Human.bar # 0 +Doctor.bar # nil + ``` |