From: "J. Ryan Sobol" <ryansobol@...>
Date: 2005-12-23T09:40:27+09:00
Subject: Re: What's the "#" for?


On Dec 22, 2005, at 7:32 PM, Joe Van Dyk wrote:

> On 12/22/05, redrhodes <richstep911@gmail.com> wrote:
>> I've started on my first ruby project and came accross the following
>> code from:
>> http://habtm.com/articles/2005/11/13/your-site-doesnt-look-too- 
>> good-in-x-browser
>>
>> Since I've managed to understand most of what's going on here, but I
>> still can't find a reference on how and why to use "#".    From
>> following the code it looks like an escape character for a  
>> variable to
>> be populated when enclosed within quotes.  Does anyone have enough
>> understanding on the syntax to help a ruby nubie?
>>
>> class Hash
>>   def to_sql
>>     sql = keys.sort {|a,b| a.to_s<=>b.to_s}.inject([[]]) do |arr,  
>> key|
>>       arr[0] << "#{key} = ?"
>>       arr << self[key]
>>     end
>>     [sql[0].join(' AND ')] + sql[1..-1]
>>   end
>> end
>
> a = "hay guys"
> puts "this is what a is: #{ a }"
>
> prints:
> this is what a is: hay guys
>

 From the Ruby.new chapter in Programming Ruby : The Pragmatic  
Programmer's Guide (http://whytheluckystiff.net/ruby/pickaxe/)

"The second thing that Ruby does with double-quoted strings is  
expression interpolation. Within the string, the sequence # 
{ expression } is replaced by the value of expression. We could use  
this to rewrite our previous method.

def sayGoodnight(name)
   result = "Goodnight, #{name}"
   return result
end

When Ruby constructs this string object, it looks at the current  
value of name and substitutes it into the string. Arbitrarily complex  
expressions are allowed in the #{...} construct."