Ruby blocks

MTK358 · 08-31-2010, 03:45 PM

I often see these blocks after a method call like this:

Code:

File::open('filename', 'w') do |f|
    f << string
end

What does this actually mean on a low level?

Sergei Steshenko · 08-31-2010, 04:07 PM

Quote:

Originally Posted by MTK358

I often see these blocks after a method call like this:

Code:

File::open('filename', 'w') do |f|
    f << string
end

What does this actually mean on a low level?

From the very first page of Yahoo matches in response to "Ruby block": http://c2.com/cgi/wiki?BlocksInRuby .

graemef · 09-01-2010, 02:38 AM

How "low level" do you want to go?

The File::open method will yield the File object, this allows the block to use this object, once the block is closed the File::open method will then close the file. Because the File::open method has just a single yield the block will be executed once, but if within the method the yield is wrapped inside a while then you will get an iterator, as is the case with the IO.each (which File will inherit)