I'm trying to add a method dynamically to a class by opening an existing
class, and it actually works. What I don't understand is why it doesn't
show up when I use the "methods" method on it afterwards.
What I do is something like this:
Code:
def method_missing name, *args
Array.class_eval "def #{name} *args; #{str}; end"
end
Afterwards I can call that method on every object of this class (new or
otherwise). However, it doesn't show up in Array.methods.
The Array.methods.length is the same both before and after that line is
executed and adds the method. However, if I do a self.methods.length the
number of methods has increased.
My question is therefore this: how can I add a method to a class (e.g.
Array) and have it show up when I do a <class>.methods on it?
It is not being defined for the Array class, but rather for instances of the
Array class. Try:
Array.instance_methods
···
On Mon, May 17, 2010 at 6:25 PM, Sam Uel <cannedlobstah@gmail.com> wrote:
Hi!
I'm trying to add a method dynamically to a class by opening an existing
class, and it actually works. What I don't understand is why it doesn't
show up when I use the "methods" method on it afterwards.
What I do is something like this:
Code:
def method_missing name, *args
Array.class_eval "def #{name} *args; #{str}; end"
end
Afterwards I can call that method on every object of this class (new or
otherwise). However, it doesn't show up in Array.methods.
The Array.methods.length is the same both before and after that line is
executed and adds the method. However, if I do a self.methods.length the
number of methods has increased.
My question is therefore this: how can I add a method to a class (e.g.
Array) and have it show up when I do a <class>.methods on it?
Fred.class_eval "def #{name} val; puts val; end"
send(name, args)
end
end
fr=Fred.new
fr.somefunc "1st time - called by the var fr"
fr.somefunc "2nd time - called by the var fr"
Fred.new.somefunc "3rd time, this one's a new instance"
The code above gives the following output:
inside method_missing
1st time - called by the var fr
2nd time - called by the var fr
3rd time, this one's a new instance
^^ Notice how the message "inside method_missing" only shows up once.
Everything is OK so far, the method somefunc seems to have correctly
added itself as an instance method to the class Fred.. but the following
confuses me:
^^ Notice how the message "inside method_missing" only shows up once.
Well it is not missing anymore as you define it when it is missing, it
is not defined temporarily.
Everything is OK so far, the method somefunc seems to have correctly
added itself as an instance method to the class Fred.. but the following
confuses me:
Yup, I run the code in its' entirety too.
Perhaps I somehow screwed up my Ruby install?
I was lazy I admit and didn't feel like reading up on how to install
Ruby, so I just DLed the latest one found here: http://rubyinstaller.org/download.html
Which version are you using, if you don't mind me asking?
@Rob: you mean declaring Fred.new.somefunc before fr.somefunc?
If so, no difference at the end - still just gives me three false.
Thanks guys for your time!
···
On Tue, May 18, 2010 at 9:13 AM, Sam Uel <cannedlobstah@gmail.com> > wrote:
On Tue, May 18, 2010 at 10:45 AM, Sam Uel <cannedlobstah@gmail.com> wrote:
Yup, I run the code in its' entirety too.
Perhaps I somehow screwed up my Ruby install?
I was lazy I admit and didn't feel like reading up on how to install
Ruby, so I just DLed the latest one found here: http://rubyinstaller.org/download.html
Which version are you using, if you don't mind me asking?
