From: Robert Klemme <shortcutter@...>
Date: 2007-11-13T19:25:15+09:00
Subject: Re: Yielding an object and caring about the result: the cousin of Object#tap

2007/11/13, furtive.clown@gmail.com <furtive.clown@gmail.com>:
> On Nov 13, 3:12 am, Robert Klemme <shortcut...@googlemail.com> wrote:
> >
> > IMHO introducing temporary variables with proper names can go a long
> > way to make this piece much more readable. (The same holds true for
> > method names.)
>
> OK, point taken about the proper name.  Nonetheless I am surprised
> this is not a unanimous slam dunk.  The contenders are:
>
>    all_inputs = source_files +
>       transform1( stems.map { |f| f + "." + guess_extension(f) } )
>    all_files = transform2( all_inputs ).map {|f| File.join dir, f}
>
> verses
>
>    all_files = stems.map { |f|
>       f + "." + guess_extension(f)
>    }.as { |all_inputs|
>       transform2(source_files + transform1(all_inputs))
>    }.map { |f|
>       File.join dir, f
>    }
>
> Since I have been accustomed to using #as for years, the latter looks
> canonical and the former looks quirky and too clever.  Three things
> come to mind:
>
> (1) Parentheses adjacent to brackets are an eyesore.

I don't subscribe to that. It depends on the individual case.

> (2) The latter is step-by-step linear and easier to follow: one
> transformation, then another, then another.  Simple.  The former takes
> much more studying in order to understand, relatively speaking.  That
> is, my strategy for understanding it is to work from the inmost
> expression outward.  But in the latter case, I work linearly from
> start to finish.

As I said, preferences differ.  Since you are used to working this way
it's easy for you. For me it took quite a bit of time until I
understood the logic.

> (3) What is the purpose of all_inputs?  Is it there as an
> intermediate, or do you want to use it for something else?  Should I
> keep a mental note of it, or should I discard it in my mind?  In the
> former case, I am left wondering all of this.  In the latter case the
> answer is clear: it's a temporary for building all_files, to be
> forgotten as soon as possible.

It never occurred to me that this could be a problem.  If you have too
many temporary variables in a method the method is probably too long
or complex anyway.

> I am a lone rubyist who went off the grid several years ago after
> contributing a project on rubyforge, so perhaps *my* style is the
> quirky one.  Still, in my mind the latter is sheer elegance compared
> to the former.  I actually find it interesting that someone could
> possibly disagree.  Do (1)-(3) make any sense, then?

Partly but I'd rather hear other voices as well.

Btw, what is all this transforming doing?  Can you give a short
description of what this piece of code is supposed to do?  As far as I
can see you have inputs source_files and stems and get a single list
of filenames out of this. Can you give some more hints about the
semantics?

Kind regards

robert

-- 
use.inject do |as, often| as.you_can - without end