From: Robert Klemme <shortcutter@...>
Date: 2006-05-22T22:48:03+09:00
Subject: Re: rubynuby - confused by method name "inject"

2006/5/22, Daniel N <has.sox@gmail.com>:
> This is a question that I have often wondered about and I think this thread
> has gone a fair way to explaining it.
>
> Just to make sure, I want to step through a call to inject (The sum example)
> to see that I have it.  Any comments would be great.
>
> [1,2,3].inject(0) { |cur_sum, elem| cur_sum + elem }
>
> Iteration 1
> cur_sum = 0, elem = 1
> cur_sum = cur_sum + elem #=> cur_sum = 0 + 1 (Replace cur_sum with the
> results of the block => 1 )
>
> Iteration 2
> cur_sum = 1, elem = 2
> cur_sum = cur_sum + elem #=> cur_sum = 1 + 2 (Replace cur_sum with the
> results of the block  => 3 )
>
> Iteration 3
> cur_sum = 3, elem = 3
> cur_sum = cur_sum + elem #=> cur_sum = 3 + 3 (Replace cur_sum with the
> results of the block  => 6 )
>
> Return cur_sum #=> 6
>
> I think that part so far is ok. I get this part. but how would I step
> through this?

Exactly the same - only values are different.

> klass = fully_qualified_name.split('::').inject(Module) { |_module,
> _symbol|
>  _module.const_get(_symbol)
> }
>
> instance = klass.new

>> class Foo;class Bar;class Baz; end end end
=> nil
>> "Foo::Bar::Baz".split(/::/).inject(Object) {|cl,n| print "-> ", cl,
", ", n, "\n"; cl.const_get(n)}.new
-> Object, Foo
-> Foo, Bar
-> Foo::Bar, Baz
=> #<Foo::Bar::Baz:0x3a3178>

Kind regards

robert