[Posted at 
http://drnicwilliams.com/2006/09/28/new-magical-version-of-symbolto_proc/]

Before the magic, let???s go through a Beginner???s Guide to Mapping, then 
Advanced Guide to Symbol.to_proc, and THEN, the magical version. Its 
worth it. Its sexy, nifty AND magical all at once.

* Beginner???s Guide to Mapping

>> list = [???1???,  ???2???, ???3???]
=> ["1???, "2???, "3???]
>> list.map {|item| item.to_i}
=> [1, 2, 3]

Here we're invoking to_i on each item of the list and returning the 
result into a new list. That's map/collect for you.

* Advanced Guide to Symbol.to_proc

After doing that a few times, you start wishing there was simpler 
syntax. Enter: Symbol.to_proc

>> list.map &:to_i
=> [1, 2, 3]

It works. Just enjoy it. (see article for links on why it works)

* Magical version of Symbol.to_proc

Quite frankly, that???s still a lot of syntax. Plus, I normally forget to 
added parentheses around the &:to_i, and then latter I want to invoke 
another method on the result, so I need to add the parentheses which is 
a pain??? anyway. I thought of something niftier and dare I say, more 
magical.

How about this syntax:

>> list.to_is
=> [1, 2, 3]

By passing the plural version of a method, the array automagically 
performs the above mapping on itself using the singular version of the 
method.

Sexy! And here's more examples:

>> (1..10).to_a.to_ss
=> ["1", "2", "3", "4", "5", "6", "7", "8", "9", "10"]
>> (1..10).to_a.days
=> [86400, 172800, 259200, 345600, 432000, 518400, 604800, 691200, 
777600, 864000]
>> [2,'two', :two].classes
=> [Fixnum, String, Symbol]
>> [2,'two', :two].classes.names
=> ["Fixnum", "String", "Symbol"]
>> [2,'two', :two].classes.names.lengths
=> [6, 6, 6]

So much happy syntax in one place!

I've got the library that gives you this syntax here: 
http://drnicwilliams.com/2006/09/28/new-magical-version-of-symbolto_proc/ 
(at the bottom)

Nic


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