基本使用:
class User
def name
"Bob"
end
end
u = User.new
p u.name # "Bob"
m = u.method(:name)
p m.owner # User
p m.source_location # ["main.rb", 2]
对于继承和引入的方法, owner 会显示定义方法的命名空间:
module Helper
def name
"Bob"
end
end
class User
include Helper
end
class Student < User
def score
100
end
end
obj = Student.new
p obj.name # "Bob"
m = obj.method(:name)
p m.owner # Helper
p m.source_location # ["main.rb", 2]
p obj.score # 100
m = obj.method(:score)
p m.owner # Student
p m.source_location # ["main.rb", 12]
普通的方法通过字符串搜索还是比较容易找到的, 动态生成的方法就很依赖这样查找.
为了方便方法的阅读和查找, 一定要通过注释补全方法名.
class User
# define_method :dance_popping
# define_method :dance_waacking
[:popping, :waacking].each do |dance_type|
method_name = "dance_#{dance_type}"
define_method(method_name) do |*args|
"Hi #{method_name}: #{args}"
end
end
end
u = User.new
p u.dance_popping("Good") # "Hi dance_popping: [\"Good\"]"
p u.dance_waacking("Perfect") # "Hi dance_waacking: [\"Perfect\"]"
m = u.method(:dance_popping)
p m.owner # User
p m.source_location # ["main.rb", 6]
或者这样:
class User
# define_method :dance_popping
# define_method :dance_waacking
[:popping, :waacking].each do |dance_type|
method_name = "dance_#{dance_type}"
class_eval <<-RUBY, __FILE__, __LINE__ + 1
def #{method_name}(*args)
"Hi #{method_name}: \#{args}"
end
RUBY
end
end
u = User.new
p u.dance_popping("Good") # "Hi dance_popping: [\"Good\"]"
p u.dance_waacking("Perfect") # "Hi dance_waacking: [\"Perfect\"]"
m = u.method(:dance_popping)
p m.owner # User
p m.source_location # ["main.rb", 7]
通过 method_missing 实现的 “方法” 不适用:
class User
private def method_missing(symbol, *args)
"Hello #{symbol}: #{args}"
end
end
u = User.new
p u.sing("Pop", "Rock") # "Hello sing: [\"Pop\", \"Rock\"]"
p (u.method(:sing) rescue "undefined method :sing") # "undefined method :sing"