In java script it is possible to something like this,
method.outputType = "string";
we are setting the return type of the method. Is this possible in Ruby?
i searched in the google and found this.
http://bias2build.com/thesis/ruby_v_js_MP.html
it says that this is not possible in Ruby.
i wanna confirm this.
help me please.
thanks!
regards,
buddhika
--
Posted via http://www.ruby-forum.com/.
Confirmed. There is virtually no metadata about a method available to the public. Arity is about the only one I can think of.
On Nov 12, 2007, at 00:35 , Thilina Buddhika wrote:
In java script it is possible to something like this,
method.outputType = "string";we are setting the return type of the method. Is this possible in Ruby?
i searched in the google and found this.
Ruby/Javascript Metaprogramming comparison
it says that this is not possible in Ruby.
i wanna confirm this.
It is possible in a round about way. In Ruby, methods are not first
class objects. (Though to go with Ruby's 100% OOP mantra you would
think they would be, but in any case...) You can make them behave as
such for the most part if you want. You have to create a method cache,
b/c #method itself will always return a new object rather than the
same one. Facets does this with #method!.
require 'facets/1stclassmethod'
class X
def initialize
meth = method!('sayit')
def meth.outputType
"String"
end
end
def sayit(msg)
puts msg.to_s
end
def tellme
method!('sayit').outputType
end
end
puts X.new.tellme #=> String
Besides #method! there is also #instance_method!. You have to realize
the limitations of this though. In Ruby instance methods are not the
same as object methods (shown above). So:
X.instance_method!('sayit') != X.new.method!('sayit')
T.
On Nov 12, 3:35 am, Thilina Buddhika <thilin...@gmail.com> wrote:
In java script it is possible to something like this,
method.outputType = "string";we are setting the return type of the method. Is this possible in Ruby?
i searched in the google and found this.
Ruby/Javascript Metaprogramming comparison
it says that this is not possible in Ruby.
i wanna confirm this.
help me please.
No, you can't *set* the return type of a method, but you can apply
metadata to describe a method. For example:
http://phrogz.net/RubyLibs/rdoc/classes/DescribeMethods.html
On Nov 12, 12:35 am, Thilina Buddhika <thilin...@gmail.com> wrote:
In java script it is possible to something like this,
method.outputType = "string";we are setting the return type of the method. Is this possible in Ruby?
Thilina Buddhika wrote:
In java script it is possible to something like this,
method.outputType = "string";we are setting the return type of the method.
Really? Care to provide an example?
Is this possible in Ruby?
i searched in the google and found this.
Ruby/Javascript Metaprogramming comparison
it says that this is not possible in Ruby.
It's not possible in javascript either.
--
Posted via http://www.ruby-forum.com/\.
Actually, this cannot work in Ruby. In Java, the return type of a method is defined, in ruby, a method has no return type.
Consider this:
def string_or_double(type)
if type == :string
return "String"
else
return 0.01
end
end
So this method can have the return type String or Double. Ruby doesn't care, so it doesn't have and can't even find out which
type is returned without executing the method.
Java, on the other hand, does care - it would only accept such a construct if I defined the method to return a generic Object.
On Nov 12, 2007, at 11:09 AM, Ryan Davis wrote:
On Nov 12, 2007, at 00:35 , Thilina Buddhika wrote:
In java script it is possible to something like this,
method.outputType = "string";we are setting the return type of the method. Is this possible in Ruby?
i searched in the google and found this.
Ruby/Javascript Metaprogramming comparison
it says that this is not possible in Ruby.
i wanna confirm this.
Confirmed. There is virtually no metadata about a method available to the public. Arity is about the only one I can think of.
Trans, you know I love your work, babe, but you've given a "Microsoft tech
support talking to the guy in the helicopter" answer (or whatever your
favorite version of that joke is).
Yes, you've just created a method on a method, but the fact that it happens
to return the word "String" doesn't tell the guy anything prescriptive
about the return type. You could just as easily return "purple", but it
doesn't mean the result will be purple.
On Mon, 12 Nov 2007 08:00:45 -0500, Trans wrote:
It is possible in a round about way. In Ruby, methods are not first
class objects. (Though to go with Ruby's 100% OOP mantra you would
think they would be, but in any case...) You can make them behave as
such for the most part if you want.
--
Jay Levitt |
Boston, MA | My character doesn't like it when they
Faster: jay at jay dot fm | cry or shout or hit.
http://www.jay.fm | - Kristoffer
[...]
In Ruby, methods are not first
class objects. (Though to go with Ruby's 100% OOP mantra you would
think they would be, but in any case...)
[...]
I used to think and wish for this too, and complain about it often.
Then, while implementing my own OOP version of Lua, I had an epiphany:
How can a method be a first-class object *and* have #super work?
For #super to work, you need a method to know what class it is
associated with, so that it can search the ancestor chain. But as soon
as you associate it with a class, it's no longer a first class object.
(If you try to use the class of the receiver, it works for one level
up, but beyond that it fails.)
For more details, see my original post on this topic. [1] Please poke
holes in it. I'd love to see how Ruby could treat all methods as first-
class objects interchangeable with blocks/procs/lambdas, unifying the
madness (which, of course, would need some way to control the
different arity handling), but I'm not seeing it as possible right
now.
[1] http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/179372
Feel free to poke holes in my argument
On Nov 12, 5:00 am, Trans <transf...@gmail.com> wrote:
Trans wrote:
Besides #method! there is also #instance_method!. You have to realize
the limitations of this though. In Ruby instance methods are not the
same as object methods (shown above). So:X.instance_method!('sayit') != X.new.method!('sayit')
Why not? Come on Trans, you can make this work! 
Hey how's that one
On Nov 12, 2007, at 3:25 PM, Jay Levitt wrote:
On Mon, 12 Nov 2007 08:00:45 -0500, Trans wrote:
It is possible in a round about way. In Ruby, methods are not first
class objects. (Though to go with Ruby's 100% OOP mantra you would
think they would be, but in any case...) You can make them behave as
such for the most part if you want.Trans, you know I love your work, babe, but you've given a "Microsoft tech
support talking to the guy in the helicopter" answer (or whatever your
favorite version of that joke is).
My bad! I didn't realize Thilina was trying to land a helicopter 
I
was focusing on the metadata propellers and not the return landing
pad.
Well, I suppose there's always
m = method(:foo)
define_method(:foo) do |str|
String(m.call(str))
end
It's a String now!
T.
On Nov 12, 9:25 am, Jay Levitt <jay+n...@jay.fm> wrote:
Trans, you know I love your work, babe, but you've given a "Microsoft tech
support talking to the guy in the helicopter" answer (or whatever your
favorite version of that joke is).Yes, you've just created a method on a method, but the fact that it happens
to return the word "String" doesn't tell the guy anything prescriptive
about the return type. You could just as easily return "purple", but it
doesn't mean the result will be purple.
So is this Lua fork available somewhere?
On Nov 12, 12:07 pm, Phrogz <phr...@mac.com> wrote:
I used to think and wish for this too, and complain about it often.
Then, while implementing my own OOP version of Lua, I had an epiphany:
[...]> In Ruby, methods are not first
> class objects. (Though to go with Ruby's 100% OOP mantra you would
> think they would be, but in any case...)[...]
I used to think and wish for this too, and complain about it often.
Then, while implementing my own OOP version of Lua, I had an epiphany:How can a method be a first-class object *and* have #super work?
You mean to unify UnboundMethod and Method. I suppose UnboundMethod
could keep a table of the classes it was in.
For #super to work, you need a method to know what class it is
associated with, so that it can search the ancestor chain. But as soon
as you associate it with a class, it's no longer a first class object.(If you try to use the class of the receiver, it works for one level
up, but beyond that it fails.)For more details, see my original post on this topic. [1] Please poke
holes in it. I'd love to see how Ruby could treat all methods as first-
class objects interchangeable with blocks/procs/lambdas, unifying the
madness (which, of course, would need some way to control the
different arity handling), but I'm not seeing it as possible right
now.[1]http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/179372
Feel free to poke holes in my argument
I'm not so sure about the #initialize thing. I think maybe your
troubles came from lua and how you went about it there. Ruby creates
an object basically like this:
class Class
def new(*a, &b)
o = allocate
o.initialize(*a, &b)
o
end
end
In fact you can use that as a basis for some fun meta-coding.
class Class
alias_method :postinitialize_new, :new
def new(*args, &blk)
o = allocate
a = ancestors
until a.empty?
m = a.pop
if m.method_defined?('preinitialize') or
m.private_method_defined?('preinitialize')
im = instance_method('preinitialize')
im.arity == 0 ? im.bind(o).call : im.bind(o).call(*args,
&blk)
end
end
o.__send__(:initialize, *args, &blk) if
o.object_class.private_method_defined?(:initialize)
o
end
end
So i don't see why it can't be:
class Class
def new(*a, &b)
o = allocate
o.new(*a, &b)
o
end
end
also, from your post, I wish ruby did this always!:
"(For those not familiar with Lua, the colon used when defining a
function means "Hey, please create an implicit first parameter named
'self', because I'm too lazy to type it each time." This is why I can
pass the 'self' from the subclasses to the parent method, and have the
initializer operate on it instead.)"
T.
On Nov 12, 10:10 am, Phrogz <phr...@mac.com> wrote:
On Nov 12, 5:00 am, Trans <transf...@gmail.com> wrote:
Xavier Noria wrote:
On Nov 12, 2007, at 3:25 PM, Jay Levitt wrote:
On Mon, 12 Nov 2007 08:00:45 -0500, Trans wrote:
It is possible in a round about way. In Ruby, methods are not first
class objects. (Though to go with Ruby's 100% OOP mantra you would
think they would be, but in any case...) You can make them behave as
such for the most part if you want.Trans, you know I love your work, babe, but you've given a "Microsoft tech
support talking to the guy in the helicopter" answer (or whatever your
favorite version of that joke is).Hey how's that one
http://www.google.com/search?q=microsoft+support+helicopter+joke
1st link:
http://www.bastichlabz.org/~tigger/TechHumor/mshelicopter.txt
Cheers,
Peter
___
http://www.rubyrailways.com
http://scrubyt.org
Trans wrote:
Well, I suppose there's always
m = method(:foo)
define_method(:foo) do |str|
String(m.call(str))
endIt's a String now!
IMO, it looks more Ruby to use the built in converter methods, even if the effect are the same as your example above.
m.call(str).to_s
Best regards,
Jari Williamsson
Peter Szinek wrote:
Hey how's that one
microsoft support helicopter joke - Google Search
1st link:
http://www.bastichlabz.org/~tigger/TechHumor/mshelicopter.txt
I only knew this variant:
A manager and an engineer
A man is flying in a hot air balloon and realizes he is lost. He reduces height and spots a man down below. He lowers the balloon further and shouts: "Excuse me, can you help me? I promised my friend I would meet him half an hour ago, but I don't know where I am."
The man below says: "Yes. You are in a hot air balloon, hovering approximately 30 feet above this field. You are between 40 and 42 degrees N. latitude, and between 58 and 60 degrees W. longitude."
"You must be an engineer" says the balloonist.
"I am" replies the man. "How did you know?"
"Well" says the balloonist, "everything you have told me is technically correct, but I have no idea what to make of your information, and the fact is I am still lost."
The man below says "You must be a manager."
"I am" replies the balloonist, "but how did you know?"
"Well", says the man, "you don't know where you are, or where you are going. You have made a promise which you have no idea how to keep, and you expect me to solve your problem. The fact is you are in the exact same position you were in before we met, but now it is somehow my fault."
---8<------8<------8<------8<------8<------8<------8<------8<---
For some readers on this mailing list this might be a familiar situation...
--
Florian Frank