Here is a blog post by Yehuda Katz about what sets Ruby blocks apart:

http://yehudakatz.com/2010/02/07/the-building-blocks-of-ruby/

That should give you a few great examples.

hth
sylvester

On Nov 24, 2011, at 5:01 PM, Jesù¸ Gabriel y GaláÏ wrote:

> On Thu, Nov 24, 2011 at 4:55 PM, Fily Salas <fs_tigre / hotmail.com> wrote:
>> Hi,
>> 
>> I have been practicing Ruby and believe it or not the hardest part for
>> me to understand (so far) is the concept of using blocks, why used them
>> and how to use them.
> 
> There are several benefits and use cases for using blocks.
> 
>> For instance, I know I don't fully understand blocks but why would you
>> use a block in the following situation.
>> 
>> text = "Some Text"
>> File.open('test_file.txt', 'a+') do |file|
>>   file.write(text)
>> end
>> 
>> Why not just ...?
>> 
>> text = "Some Text"
>>  file = File.open('test_file1.txt', 'a+')
>> file.write(text)
>> ..why use a block instead?
> 
> This is quite straightforward: in this situation the use case is that
> you want to ensure that something happens before and after the block
> code. In this case, the File#open method opens the file, then calls
> the block and then ensures that the file is closed, even in the face
> of an exception within the block.
> 
> So, first use case: when you want code executed around code that is
> not under your control.
> 
> Another use case is when you provide a generic functionality that can
> applied to many situations, but you want to leave the exact detailed
> behavior to the client code. For example, the Enumerable#each method
> provides its clients with the capability of traversing an enumerable
> instance, doing something with each element one at a time. What you do
> with the element is responsibility of the client code, so the each
> method just accepts a block to achieve that.
> 
> Hope this helps and I hope the concept clicks soon, because it's one
> of the things that make Ruby so wonderful.
> 
> Jesus.
> 
> 
>> 1-What would be a good rule of thumb to know when to use blocks?
>> 2-What would be the easiest way to understand block?
>> 3-Can someone be so kind and explain block a little bit?
>> 
>> Thanks a lot for all of your help!
>> Learning a lot in this forum. Awesome people!
>> 
>> --
>> Posted via http://www.ruby-forum.com/.
>> 
>> 
>