From: Daniel N <has.sox@...>
Date: 2006-05-22T20:56:21+09:00
Subject: Re: rubynuby - confused by method name "inject"

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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 =3D 0, elem =3D 1
cur_sum =3D cur_sum + elem #=3D> cur_sum =3D 0 + 1 (Replace cur_sum with th=
e
results of the block =3D> 1 )

Iteration 2
cur_sum =3D 1, elem =3D 2
cur_sum =3D cur_sum + elem #=3D> cur_sum =3D 1 + 2 (Replace cur_sum with th=
e
results of the block  =3D> 3 )

Iteration 3
cur_sum =3D 3, elem =3D 3
cur_sum =3D cur_sum + elem #=3D> cur_sum =3D 3 + 3 (Replace cur_sum with th=
e
results of the block  =3D> 6 )

Return cur_sum #=3D> 6

I think that part so far is ok. I get this part. but how would I step
through this?


klass =3D fully_qualified_name.split('::').inject(Module) { |_module,
_symbol|
 _module.const_get(_symbol)
}

instance =3D klass.new






On 5/22/06, Leslie Viljoen <leslieviljoen@gmail.com> wrote:
>
> On 5/22/06, Leslie Viljoen <leslieviljoen@gmail.com> wrote:
> > On 5/22/06, Regg Mr <spamwhite@cox.net> wrote:
> > > Leslie Viljoen wrote:
> > > > On 5/21/06, Jim Weirich <jim@weirichhouse.org> wrote:
> > > >> Jeff Pritchard wrote:
> > > >> > As for Inject, nobody has come up with a wording that makes any
> sense to
> > > >> > me yet.  Does Inject have any aliases/synonyms?
> > > >>
> > > >> How I remember:  Inject takes a binary operation (e.g. +) and
> injects it
> > > >> between each element of a list.
> > > >>
> > > >>    [1,2,3].inject { |a,b| a+b }  =3D> 1+2+3
> > > >
> > > > Awesome! That really helps me!
> > >
> > >
> > > Seems like "sum" would have been a better name.
> >
> > Or an alias inject_operator perhaps...
> > This thread has discussed "sum" already and it's no good because you
> > can use any operator. I also like "accumulate" as mentioned, but
> > inject_operator is sooo clear to me.
>
> ..though the other uses of inject defy "inject_operator"...
>
> data =3D [[1, 7, 3], [1, 2], [1, 5, 4, 1], [1, 8]]
>
> longest_sample =3D nil
> longest_length =3D data.inject(0) do |accum, sample|
>         if accum > sample.length
>                 accum
>         else
>                 longest_sample =3D sample
>                 sample.length
>         end
> end
>
> puts "Longest sample: #{longest_sample.inspect}, length #{longest_length}=
"
>
> ..then again, using inject to find longest seems a bit silly...
>
> longest_sample =3D data[0]
> data.each do |sample|
>         longest_sample =3D sample if sample.length > longest_sample.lengt=
h
> end
> puts "Longest sample: #{longest_sample.inspect}, length #{longest_length}=
"
>
>

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