[英]Ruby: undefined method * for nil nilclass
I got the undefined method * for this code running in irb. 对于在irb中运行的此代码,我有未定义的方法*。 I'm using ruby 2.0.0p195 (2013-05-14) [i386-mingw32] on Windows 7 x32.
我在Windows 7 x32上使用ruby 2.0.0p195(2013-05-14)[i386-mingw32]。 It does two simple classes for geometrical shapes.
它为几何形状做了两个简单的类。
class Shape
ERR = 'Error: area or perimeter method missing.'
PI = 3.14159265358
attr_accessor :id
def initalize(id = 'shape')
@id = id
end
def get_area
raise ERR
end
def get_perimeter
raise ERR
end
def to_s
"id: #{@id}, area: #{get_area}, perimeter: #{get_perimeter}"
end
end
class Triangle < Shape
attr_accessor :a, :b, :c, :h
def initalize(id = 'triangle', a = 1, b = 2, c = 3, h = 4)
@id = id
@a, @b, @c, @h = a, b, c, h
end
def get_area
@b * @h * 0.5
end
def get_perimeter
@a + @b + @c
end
end
These are the commands with irb. 这些是带有irb的命令。
irb(main):001:0> load 'shapes.rb'
=> true
irb(main):002:0> tri = Triangle.new
=> #<Triangle:0x22d17c8>
irb(main):003:0> puts tri
NoMethodError: undefined method `*' for nil:NilClass
from shapes.rb:41:in `get_area'
from shapes.rb:28:in `to_s'
from (irb):3:in `puts'
from (irb):3:in `puts'
from (irb):3
from D:/Ruby/bin/irb:12:in `<main>'
You misspelled the method initialize
and you wrote initalize
. 您拼写了
initialize
方法,并写了initalize
。
That's why one of your variables is nil
and the tipical exception NoMethodError: undefined method ... for nil:NilClass
is raising. 这就是为什么您的变量之一为
nil
并且出现NoMethodError: undefined method ... for nil:NilClass
异常NoMethodError: undefined method ... for nil:NilClass
。
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