Re: Newbie questions on the meanings of things in Ruby

I'm going to explain the sentence syntactically, not what it does:

Puppet::Type.type(:file).provide :posix do

Puppet is a module which have a class Type,
calls method type with the parameter :file(which is a symbol),
then call a method provide(the Puppet lib uses method chaining to create a
domain specific language(DSL), google the terms if you must),
and this method provide has a parameter :posix.

The do .. end is a block.

I advise you to get the basics straight before you dive into that kind of
code.

Have a good day!

On Mon, Jul 16, 2012 at 4:14 AM, Jes俍 Gabriel y Gal疣 <
[e-mail]> wrote:

> On Mon, Jul 16, 2012 at 9:04 AM, Alex S. <[e-mail]> wrote:
> > Hi,
> >
> > I am tasked with the development of puppet provider. I am a few days
> > into Ruby and looking at the existing providers I am finding it hard to
> > interpret - I went over Ruby pargprog book and I am still not sure what
> > the following syntax means. I was hoping someone might be kind enough to
> > guide me through the terms here. This is the code  fragment I am
> > struggling to understand:
> >
> > Puppet::Type.type(:file).provide :posix do
> >   desc "Uses POSIX functionality to manage file ownership and
> > permissions."
> >
> >   confine :feature => :posix
> >
> >   include Puppet::Util::POSIX
> >   include Puppet::Util::Warnings
> >
> >   require 'etc'
> >
> >   def uid2name(id)
> >     return id.to_s if id.is_a?(Symbol) or id.is_a?(String)
> >     return nil if id > Puppet[:maximum_uid].to_i
> >
> >     begin
> >       user = Etc.getpwuid(id)
> >     rescue TypeError, ArgumentError
> >       return nil
> >     end
> >
> >     if user.uid == ""
> >       return nil
> >     else
> >       return user.name
> >     end
> >   end
> >
> > ....
> >
> > end
> >
> > In particular I am finding it hard to understand what the first line
> > means -
> >
> > Puppet::Type.type(:file).provide :posix do
> >
> > ?
> >
> > Is this some sort of dynamic class (Type) extension? If so is there a
> > resource I can go to dig up a bit more on this?
>
> I've never used Puppet, so I can only comment on the syntax part:
>
> Puppet::Type is a constant, which looks like it refers to a class or
> module.
> You are calling the method #type of that class or module, passing the
> parameter :file (which is a symbol).
> In order to read more documentation about this method, you can ri
> Puppet::Type#type or look into Puppet's documentation.
> This method returns an object, on which you call the method #provide,
> passing the argument :posix and a block. A block is what is contained
> between the do...end syntax, so basically the rest of the snippet is
> the block you pass.
>
> Without knowing anything about Puppet, it seems that this piece of
> code creates a new class or an extension for Puppet's file type, in
> order to provide this uid2name method.
>
> Hope this helps,
>
> Jesus.
>
>