From: Emmanuel Surleau <emmanuel.surleau@...>
Date: 2008-08-29T05:11:54+09:00
Subject: Re: How would this Perl script look in Ruby?

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On Thu, Aug 28, 2008 at 2:51 PM, Robert Klemme
<shortcutter@googlemail.com>wrote:

> 2008/8/28 Avinash Magar <avinash.magar@gmail.com>:
> > Nathan Powell wrote:
> >> Why don't you show us what you have, and where you are stuck, rather
> >> than us translating it for you in it's entirety.
> >>
> > sorry about that.
> > things I would like to know are:
> >
> > 1) How would we write following method?
> >   the one which takes an array and return subref (whatever equivalent
> > in Ruby)
> >   something like this(in perl)
> > sub get_random_val_generator {
> >    my $arr =3D shift;
> >    return sub { return $arr->[ rand @$arr] };
> > }
>
> You can do
>
> array =3D ...
> rand_gen =3D lambda { array[rand(array.size)] }
> ...
> item =3D rand_gen[]  # or
> item =3D rand_gen.call
>
> > 2) How to store these references(subrefs) in a hash or some variable?
>
> hash[some_key] =3D some_object # everything is an object
>
> > 3) How would you do(approach) this in Ruby(the script)?
>
> My Perl is a bit rusty and, frankly, I'm not inclined to spent the
> efforts to analyze it. Can you describe it?


Unless I'm mistaken, the gist of it is:

Take a bunch of templates:

adm has _QTY_ _CAR_ cars
ssn has _QTY_ _CAR_ cars

In an infinite loop, pick one randomly, and replace the _QTY_ and _CAR_
placeholders by values taken from the 'vals' fields in the following hash:

my %value_map =3D (
   '_CAR_' =3D> {
       'order' =3D> 'rand',
       'vals' =3D> [qw(bentley merc bmw audi porsche ford honda lexus)]
       },
   '_QTY_' =3D> {
       'order' =3D> 'rand',
       'vals' =3D> [1..10]
       }
);

The way values are chosen depends on the 'order' field, which can be either
random ('rand') or sequential ('seq').

In ruby, you could replace the value_map by using a more class-oriented
approach:

RandomMessageValue.new(:qty, (1..10).to_a)
RandomMessageValue.new(:car, %w(bentley merc bmw audi porsche ford honda
lexus)

And you have SeqMessageValue if you want something sequential.
Both RandomMessageValue and SeqMessageValue inherit from MessageValue.
A MessageValue object knows how to choose the next value in the array of
values (with different implementations). Then you just need a Message class=
,
which has a list of templates, and a list of MessageValue objects. Message
knows how to replace the content of a MessageValue inside a template.

Voil=E0.

Cheers,

Emm

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