Starting in Ruby 1.9.3, we can create private constants:
从Ruby 1.9.3开始,我们可以创建私有常量:
module M
class C; end
private_constant :C
end
Is there a good documentation about what this does? Is there a way to get the names of only private constants similar to calling constants
关于它的作用是否有良好的文档?有没有办法获得类似于调用常量的私有常量的名称
2 个解决方案
#1
3
As of Ruby 2.1, while Module#constants
includes only public constants, if you set inherit=false
, you will get private constants as well. So if you find a constant in constants(false)
but not in constants
(and you don't care about inherited constants), that might be a more or less reliable way to tell if it's private.
从Ruby 2.1开始,虽然Module#常量仅包含公共常量,但如果设置inherit = false,则还会获得私有常量。因此,如果您在常量中找到常量(false)但不在常量中找到常量(并且您不关心继承的常量),那么这可能是一种或多或少可靠的方式来判断它是否是私有的。
class Module
def private_constants
constants(false) - constants
end
end
module Foo
X = 1
Y = 2
private_constant :Y
end
puts "Foo.constants = #{Foo.constants}"
puts "Foo.constants(false) = #{Foo.constants(false)}"
puts "Foo.private_constants = #{Foo.private_constants}"
# => Foo.constants = [:X]
# => Foo.constants(false) = [:X, :Y]
# => Foo.private_constants = [:Y]
This is undocumented, and I'm not sure if it's intentional, but empirically it works. I would back it up with unit tests.
这是没有证件的,我不确定它是否有意,但凭经验可行。我会用单元测试来支持它。
Update: It looks like this is a bug in Ruby, and may disappear in a future version.
更新:看起来这是Ruby中的一个错误,并且可能在将来的版本中消失。
#2
10
There is no such thing as private constants until Ruby 1.9.3. To get a list of all the constants though, you can simply use constants
.
在Ruby 1.9.3之前,没有私有常量这样的东西。要获得所有常量的列表,您可以简单地使用常量。
module Mod
CONST = "value"
end
Mod.constants #=> [:CONST]
From 1.9.3, private_constant
was added, but as nothing is really private, you can do...
从1.9.3开始,添加了private_constant,但由于没有什么是私密的,你可以做......
module Mod
CONST = "value"
private_constant :CONST
end
Mod.const_get(:CONST) #=> "value"
I don't think there is a way of getting a list of all the private constants but you can still test the presence of a particular name.
我不认为有一种获取所有私有常量列表的方法,但您仍然可以测试特定名称的存在。
Mod.const_defined?(:CONST) #=> true
#1
3
As of Ruby 2.1, while Module#constants
includes only public constants, if you set inherit=false
, you will get private constants as well. So if you find a constant in constants(false)
but not in constants
(and you don't care about inherited constants), that might be a more or less reliable way to tell if it's private.
从Ruby 2.1开始,虽然Module#常量仅包含公共常量,但如果设置inherit = false,则还会获得私有常量。因此,如果您在常量中找到常量(false)但不在常量中找到常量(并且您不关心继承的常量),那么这可能是一种或多或少可靠的方式来判断它是否是私有的。
class Module
def private_constants
constants(false) - constants
end
end
module Foo
X = 1
Y = 2
private_constant :Y
end
puts "Foo.constants = #{Foo.constants}"
puts "Foo.constants(false) = #{Foo.constants(false)}"
puts "Foo.private_constants = #{Foo.private_constants}"
# => Foo.constants = [:X]
# => Foo.constants(false) = [:X, :Y]
# => Foo.private_constants = [:Y]
This is undocumented, and I'm not sure if it's intentional, but empirically it works. I would back it up with unit tests.
这是没有证件的,我不确定它是否有意,但凭经验可行。我会用单元测试来支持它。
Update: It looks like this is a bug in Ruby, and may disappear in a future version.
更新:看起来这是Ruby中的一个错误,并且可能在将来的版本中消失。
#2
10
There is no such thing as private constants until Ruby 1.9.3. To get a list of all the constants though, you can simply use constants
.
在Ruby 1.9.3之前,没有私有常量这样的东西。要获得所有常量的列表,您可以简单地使用常量。
module Mod
CONST = "value"
end
Mod.constants #=> [:CONST]
From 1.9.3, private_constant
was added, but as nothing is really private, you can do...
从1.9.3开始,添加了private_constant,但由于没有什么是私密的,你可以做......
module Mod
CONST = "value"
private_constant :CONST
end
Mod.const_get(:CONST) #=> "value"
I don't think there is a way of getting a list of all the private constants but you can still test the presence of a particular name.
我不认为有一种获取所有私有常量列表的方法,但您仍然可以测试特定名称的存在。
Mod.const_defined?(:CONST) #=> true