Tuesday, March 11, 2008

Relationship of Object and Kernel

# Object mixes in the Kernel module, making the built-in kernel functions globally accessible. The instance methods of Object are defined by the Kernel module.

p Kernel.instance_methods(false).length # 42 # Object instance methods
p Kernel.methods(false).length # 65 # Kernel module methods
p Module.instance_methods(false).length # 34 # Module instance methods, Kernel module is instance of Module class.
p Kernel.methods.length # 134

kernel_instance_methods = Kernel.instance_methods(false)
kernel_module_methods = Kernel.methods(false)
module_instance_methods = Module.instance_methods(false)

kernel_methods = [] # 134

Kernel Module include module methods(such as puts/p/gsub...) and module instance methods(such as __id__/__send__/id/send/object_id...), Object class has not defined instance methods, its instance methods are mixed in from Kernel module.

Kernel.methods include three group methods: object instance methods and Kernel module methods and instance methods of class Module.
class A
def self.method1
p A.method1
# A
p A.methods(false)
# ["method1"]

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