Okay, I'm trying to mock up a class object. It needs to do two
things:
1. Respond to #new with a object *I* provide, rather than a new
instance of the class; and
2. Contain a constant, such that code containing 'MyMockClass::FOO'
will work.
I can think of a naive implementation:
class MyMockClass
FOO="some value"
def self.set_instance(inst)
@instance=inst
end
def self.new(*)
return @instance
end
end
I'm wondering, though, is there a way to do this inline with
metaprogramming, and avoid defining the set_instance method? I've
tried something like this:
my_instance=...
Class.new :MyMockClass {
const_set :FOO, "some value"
define_method(:new) do |*|
return my_instance
end
}
But that doesn't work, because the define_method is creating an
instance method, not a class method. I've also tried to use a regular
old object, instead of a class object, but then the constant (FOO)
doesn't work. Any ideas?
Okay, I'm trying to mock up a class object. It needs to do two
things:
1. Respond to #new with a object *I* provide, rather than a new
instance of the class; and
2. Contain a constant, such that code containing 'MyMockClass::FOO'
will work.
[...]
I'm wondering, though, is there a way to do this inline with
metaprogramming, and avoid defining the set_instance method? I've
tried something like this:
my_instance=...
Class.new :MyMockClass {
const_set :FOO, "some value"
define_method(:new) do |*|
return my_instance
end
}
But that doesn't work, because the define_method is creating an
instance method, not a class method. I've also tried to use a regular
old object, instead of a class object, but then the constant (FOO)
doesn't work. Any ideas?
You're actually dealing with two classes: MyMockClass, and
MyMockClass's singleton class. So you would probably want to do
something like this:
# This is to make it look nicer (as per the
# pending RCR
module Kernel
def singleton_class
class << self; self; end
end
end
"Avdi Grimm" <Avdi_B_Grimm@raytheon.com> schrieb im Newsbeitrag
news:ur7hep6w5.fsf@raytheon.com...
Okay, I'm trying to mock up a class object. It needs to do two
things:
1. Respond to #new with a object *I* provide, rather than a new
instance of the class; and
2. Contain a constant, such that code containing 'MyMockClass::FOO'
will work.
I can think of a naive implementation:
class MyMockClass
FOO="some value"
def self.set_instance(inst)
@instance=inst
end
def self.new(*)
return @instance
end
end
I'm wondering, though, is there a way to do this inline with
metaprogramming, and avoid defining the set_instance method? I've
tried something like this:
my_instance=...
Class.new :MyMockClass {
const_set :FOO, "some value"
define_method(:new) do |*|
return my_instance
end
}
But that doesn't work, because the define_method is creating an
instance method, not a class method. I've also tried to use a regular
old object, instead of a class object, but then the constant (FOO)
doesn't work. Any ideas?
You don't really need to make it so complicated IMHO:
class MockClass
def initialize(obj) @obj = obj end
def new() @obj end
end
MockClass::Foo = MockClass.new "foo"
=> #<MockClass:0x10189e38 @obj="foo">
MockClass::Foo.new
=> "foo"
MockClass::Foo.new.object_id
=> 135024424
MockClass::Foo.new.object_id
=> 135024424
MockClass::Foo.new.object_id
=> 135024424
MockClass::Foo.new.object_id
=> 135024424
Alternative
class MockClass
def initialize(sym, obj) @obj = obj
self.class.const_set sym, self
end
def new() @obj end
end
p MyMockClass::FOO # "some value"
p MyMockClass.new # ""
Thanks, that looks exactly like what I was looking for. It reveals
that I don't understand Ruby metaprogramming quite as well as I
thought, though. Would you mind explaining what singleton_instance is
doing, and how it differs from just using 'self' in the class
definition?
