Storing methods in arrays or hashes

[Philliam Auriemma]

Hey all,
I'm pretty new to ruby, and I absolutely love it. I have aquestion. I
have programmed in a language called lua before (which had real full-
fledged anonymous functions), and with a lua table, which is Lias
version of a hash and an arrary combined, you could do something like
this:

newtable = { 1 = function() print("hi from 1") end,
2 = function() print("hi from 2") end
}

even though some of you haven't even ever heard of lua before, it's
easy to guess what this does: it creates two keys, 1 and 2, in a
table, newtable, and assigns two functions as their values. After
doing that, you can do this:

newtable[1]()

To call the function stored in newtable[1]. All that begs the
question: is something similar available in ruby?

 

[Eva]

Hey all,
I'm pretty new to ruby, and I absolutely love it. I have aquestion. I
have programmed in a language called lua before (which had real full-
fledged anonymous functions), and with a lua table, which is Lias
version of a hash and an arrary combined, you could do something like
this:

newtable = { 1 = function() print("hi from 1") end,
2 = function() print("hi from 2") end
}

This calls a dispatch.
Though I also don't know how ruby will write it, but I think maybe using
symbols is a way.

Eva.

 

[Bill Kelly]

newtable = { 1 = function() print("hi from 1") end,
2 = function() print("hi from 2") end
}

# here's an example, similar to the above, but
# also passing an argument:

newhash = { 1 => lambda {|x| puts("#{x} from 1")},
2 => lambda {|x| puts("#{x} from 2")}
}

newhash[1].call("hi")
newhash[2]["bye"] # alternate call syntax


# produces:
hi from 1
bye from 2



Hope this helps,

Bill

 

[Robert Klemme]

Hey all,
I'm pretty new to ruby, and I absolutely love it. I have aquestion. I
have programmed in a language called lua before (which had real full-
fledged anonymous functions), and with a lua table, which is Lias
version of a hash and an arrary combined, you could do something like

Just out of curiosity: where is the array in your Lua case? In Ruby you
would not need an Array for this - or rather, you need either an Array
or a Hash.

this:

newtable = { 1 = function() print("hi from 1") end,
2 = function() print("hi from 2") end
}

even though some of you haven't even ever heard of lua before, it's
easy to guess what this does: it creates two keys, 1 and 2, in a
table, newtable, and assigns two functions as their values. After
doing that, you can do this:

newtable[1]()

To call the function stored in newtable[1]. All that begs the
question: is something similar available in ruby?

Yes. (I'm inclined to say "Of course!" ) Please see Bill's
explanation.

Additional note: since the advent of Ruby 1.9 you can also use another
syntax for anonymous functions:

f = ->(args) { code }

newtable = {
1 => -> { puts "hi from 1" },
2 => -> { puts "hi from 2" },
}

If you only have numeric indexes in sequence you can also use an Array
instead of a Hash:

newtable = [
-> {}, # index 0
-> { puts "hi from 1" },
-> { puts "hi from 2" },
]

Kind regards

robert

 

[Philliam Auriemma]

Hey all,
I'm pretty new to ruby, and I absolutely love it. I have aquestion. I
have programmed in a language called lua before (which had real full-
fledged anonymous functions), and with a lua table, which is Lias
version of a hash and an arrary combined, you could do something like

Just out of curiosity: where is the array in your Lua case?  In Ruby you
would not need an Array for this - or rather, you need either an Array
or a Hash.

this:

newtable = { 1 = function() print("hi from 1") end,
                   2 = function() print("hi from 2") end
}

even though some of you haven't even ever heard of lua before, it's
easy to guess what this does: it creates two keys, 1 and 2, in a
table, newtable, and assigns two functions as their values. After
doing that, you can do this:

newtable[1]()

To call the function stored in newtable[1]. All that begs the
question: is something similar available in ruby?

Yes.  (I'm inclined to say "Of course!" )  Please see Bill's
explanation.

Additional note: since the advent of Ruby 1.9 you can also use another
syntax for anonymous functions:

f = ->(args) { code }

newtable = {
   1 => -> { puts "hi from 1" },
   2 => -> { puts "hi from 2" },

}

If you only have numeric indexes in sequence you can also use an Array
instead of a Hash:

newtable = [
   -> {}, # index 0
   -> { puts "hi from 1" },
   -> { puts "hi from 2" },
]

Kind regards

        robert

Holy crap that's awesome. Thanks for telling me about the new syntax
for anonymous function Rob, it just makes me love ruby even more now.
Thanks again guys.