On Thu, 30 Jul 2009 17:57:48 -0400, Luis Zarrabeitia wrote:
> As I understood the question, it was "was wrong in 'for var in
> container' in comparison with ruby's container.each?"
>
> What's the (semantic) difference between
>
> for localVar in container:
> block
>
> and
>
> container.each{|localVar| block}
I don't think "each" is a particularly compelling example of Ruby's
blocks - as you say, it's easily replaceable with a Python for-loop. The
advantage of Ruby's syntax is that it allows you to define further
functions that are sort-of like new control structures. So you have
things like:
File.open('myfile', 'r') do |file|
while line = file.gets
puts line
end
end
Which is like a python's:
with open('myfile', 'r) as f:
for line in f:
print f
However, with Ruby, this kind of scoping construct can be added without
adding new syntax. Another interesting example is the Sinatra web
framework, which allows you to write a web app with something like:
get '/' do
"Index page"
end
post '/:name' do
"Posted to " + params[:name]
end
Which looks something like a DSL for web apps, but is accomplished solely
with normal ruby functions. More: http://www.sinatrarb.com/intro.html
Ruby blocks are, fundamentally, syntactic sugar, but they are kind of
neat.
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