Comments on: An introduction to code blocks

By: Ruby Rocks -- à la Francois Montagne | Montreal Tech Watch

Ruby Rocks -- à la Francois Montagne | Montreal Tech Watch — Mon, 13 Aug 2007 18:49:15 +0000

[...] 3 times. Instead, you just have to use a Ruby key concept called “code blocks” (have a look at this post if you want to know more about code blocks). Secondly, do you see where is the conditional operation? Yep! at the end of the [...]

By: Sebastian

Sebastian — Fri, 23 Mar 2007 22:51:33 +0000

That is assuming we wanted to provide a pure ruby implementation of the idea that the times method is based on and not depend on anything defined in the superclass.

By: Peter Cooper

Peter Cooper — Fri, 23 Mar 2007 22:14:51 +0000

How’s that cleaner than self.times do … end ?

By: Sebastian

Sebastian — Fri, 23 Mar 2007 14:26:42 +0000

The code for the Integer#times implementation could be a bit cleaner. To match how the real Integer class behaves, you’d do something like:
class Integer
def times
# we can give for loops a Range to make it a bit cleaner
for i in 0…self
# just like the default times implementation we yield the current index
# your block doesn’t have to handle this so this will work for
# blocks with any number of arguments
yield i
end
# the default implementation returns a reference to itself after it’s done
self
end
end

By: Peter Cooper

Peter Cooper — Thu, 22 Mar 2007 16:22:46 +0000

I must confess I haven’t really read much of this, I just wanted to throw out an inspiration in case he was stuck :)

I guess generally in these situations you would use a collection. At least, that’s how Rails does it. find(:all).each do.. end.. etc. :)

By: Frank

Frank — Thu, 22 Mar 2007 10:57:05 +0000

I think Peter understood the question better than me. He’s right. By using a hash, the order of the various parameters doesn’t matter anymore.

By: Peter Cooper

Peter Cooper — Thu, 22 Mar 2007 04:22:01 +0000

Dan:

def list_users(params)
..
yield params
..
end

list_users( :name => name, :password => password, :userid => id ) do |user|
.. whatever .. user[:name] etc.
end

By: Frank

Frank — Wed, 21 Mar 2007 16:48:08 +0000

Dan, you have to know in advance what are the “requirements” for that method. For example, the Array class exposes a method named “each” that loop through every elements of an array instance. At every passages in the loop, the each method will yield the current item in the collection. You have to know in advance this fact to use the each method properly. I hope it does answer your question.

To everyone else, click on Dan’s link to do some remarkable javascript katas!

By: Dan

Dan — Wed, 21 Mar 2007 16:06:40 +0000

Question : how do I know the parameters passed by the yield() in a class that I do not see the source code?

I mean, I have yield(name, password, userid) in a list_users() function of a User class that I do not own the code?

When I call it, how can I know that the parameters are name, password, userid in that order?