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felipekk-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

2007-Dec-11 05:51 UTC

Hash as arguments of a method call

Hi all,

I''m writing a new class, and in the initialize I have:
class Statement
  def initialize(*args)
    @args = args[0]
    @args[:start_at] = 30.days.ago if @args[:start_at].nil?
    @args[:finish_at] = Date.today if @args[:finish_at].nil?
    @customer = Customer.find(@args[:customer_id])
  end

  (...)

end

This allows me, as you can see, to use @args[:customer_id] for example
to read arguments passed to the initialize. This is helpful in case I
need to add some more arguments to my method without breaking existing
calls.

This code is currently working (did not test it very long).

My question is: Why do I have to do the @args = args[0] thingy? I
mean, I noticed that args was an Array instead of a hash, so thats why
I did it. Is this correct? It doesnt look good...

Thanks!
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Ryan Bigg

2007-Dec-11 06:00 UTC

head link

Re: Hash as arguments of a method call

The arguments are passed in as an array due to your specification of *args.
If you don''t want to args[0] specify:

def initialize(args)

And then you will be able to access it as

args[:start_at]

On Dec 11, 2007 4:21 PM, felipekk-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
<felipekk-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> Hi all,
>
> I''m writing a new class, and in the initialize I have:
> class Statement
>  def initialize(*args)
>    @args = args[0]
>    @args[:start_at] = 30.days.ago if @args[:start_at].nil?
>    @args[:finish_at] = Date.today if @args[:finish_at].nil?
>    @customer = Customer.find(@args[:customer_id])
>  end
>
>  (...)
>
> end
>
> This allows me, as you can see, to use @args[:customer_id] for example
> to read arguments passed to the initialize. This is helpful in case I
> need to add some more arguments to my method without breaking existing
> calls.
>
> This code is currently working (did not test it very long).
>
> My question is: Why do I have to do the @args = args[0] thingy? I
> mean, I noticed that args was an Array instead of a hash, so thats why
> I did it. Is this correct? It doesnt look good...
>
> Thanks!
> >
>

-- 
Ryan Bigg
http://www.frozenplague.net

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felipekk-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

2007-Dec-11 06:07 UTC

head link

Re: Hash as arguments of a method call

I just read somewhere on AWDWR that the * makes it so that it accepts
every argument passed, generating an array.

So I thought that if I used method(args) it would accept only one arg
o.O

Thanks once again Ryan!

On Dec 10, 10:00 pm, "Ryan Bigg"
<radarliste...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> The arguments are passed in as an array due to your specification of *args.
> If you don''t want to args[0] specify:
>
> def initialize(args)
>
> And then you will be able to access it as
>
> args[:start_at]
>
> On Dec 11, 2007 4:21 PM, felip...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
<felip...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
>
>
>
>
> > Hi all,
>
> > I''m writing a new class, and in the initialize I have:
> > class Statement
> >  def initialize(*args)
> >    @args = args[0]
> >    @args[:start_at] = 30.days.ago if @args[:start_at].nil?
> >    @args[:finish_at] = Date.today if @args[:finish_at].nil?
> >    @customer = Customer.find(@args[:customer_id])
> >  end
>
> >  (...)
>
> > end
>
> > This allows me, as you can see, to use @args[:customer_id] for example
> > to read arguments passed to the initialize. This is helpful in case I
> > need to add some more arguments to my method without breaking existing
> > calls.
>
> > This code is currently working (did not test it very long).
>
> > My question is: Why do I have to do the @args = args[0] thingy? I
> > mean, I noticed that args was an Array instead of a hash, so thats why
> > I did it. Is this correct? It doesnt look good...
>
> > Thanks!
>
> --
> Ryan Bigghttp://www.frozenplague.net--~--~---------~--~----~------------~-------~--~----~
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Ryan Bigg

2007-Dec-11 06:11 UTC

head link

Re: Hash as arguments of a method call

You misinterpreted what it meant.

*args stores all the arguments as an array, but if you pass in a hash the
hash is interpreted as just one argument, so you''re able to specify
many
keys within the hash with it being just the one argument.


On Dec 11, 2007 4:37 PM, felipekk-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
<felipekk-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> I just read somewhere on AWDWR that the * makes it so that it accepts
> every argument passed, generating an array.
>
> So I thought that if I used method(args) it would accept only one arg
> o.O
>
> Thanks once again Ryan!
>
> On Dec 10, 10:00 pm, "Ryan Bigg"
<radarliste...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > The arguments are passed in as an array due to your specification of
> *args.
> > If you don''t want to args[0] specify:
> >
> > def initialize(args)
> >
> > And then you will be able to access it as
> >
> > args[:start_at]
> >
> > On Dec 11, 2007 4:21 PM,
felip...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
<felip...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> >
> >
> >
> >
> >
> > > Hi all,
> >
> > > I''m writing a new class, and in the initialize I have:
> > > class Statement
> > >  def initialize(*args)
> > >    @args = args[0]
> > >    @args[:start_at] = 30.days.ago if @args[:start_at].nil?
> > >    @args[:finish_at] = Date.today if @args[:finish_at].nil?
> > >    @customer = Customer.find(@args[:customer_id])
> > >  end
> >
> > >  (...)
> >
> > > end
> >
> > > This allows me, as you can see, to use @args[:customer_id] for
example
> > > to read arguments passed to the initialize. This is helpful in
case I
> > > need to add some more arguments to my method without breaking
existing
> > > calls.
> >
> > > This code is currently working (did not test it very long).
> >
> > > My question is: Why do I have to do the @args = args[0] thingy? I
> > > mean, I noticed that args was an Array instead of a hash, so
thats why
> > > I did it. Is this correct? It doesnt look good...
> >
> > > Thanks!
> >
> > --
> > Ryan Bigghttp://www.frozenplague.net
> >
>

-- 
Ryan Bigg
http://www.frozenplague.net

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Frederick Cheung

2007-Dec-11 08:53 UTC

head link

Re: Hash as arguments of a method call

On 11 Dec 2007, at 05:51, felipekk-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
wrote:
>
> Hi all,
>
> I''m writing a new class, and in the initialize I have:
> class Statement
>  def initialize(*args)
>    @args = args[0]
>    @args[:start_at] = 30.days.ago if @args[:start_at].nil?
>    @args[:finish_at] = Date.today if @args[:finish_at].nil?
>    @customer = Customer.find(@args[:customer_id])
>  end
>
>  (...)
>
> end
> This code is currently working (did not test it very long).
>
> My question is: Why do I have to do the @args = args[0] thingy? I
> mean, I noticed that args was an Array instead of a hash, so thats why
> I did it. Is this correct? It doesnt look good...
>That''s what *args does: it collects all the arguments  into an array.  
If your method takes as a single argument a hash of options, then why  
bother with the *args ?

Fred

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Thorsten Mueller

2007-Dec-12 20:27 UTC

head link

Re: Hash as arguments of a method call

what you define here is a variable length argument list
you get all argument passed as an array, not a hash

you could call it like:
initialize({:a=>1,:b=>2},{:a=>3,:b=>4})
and get an array with two hashes

to pass a single hash, you can use a simple parameter
def initialize(args_hash)
call it with the hash
initialize({:start_at => ''whatever, :finish_at =>
''now''})
or
initialize(:start_at => ''whatever, :finish_at =>
''now'')
since you can omit the curly braces for the last or only
hash argument
-- 
Posted via http://www.ruby-forum.com/.

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Rails - Dec 2007 - Hash as arguments of a method call

Hash as arguments of a method call

Re: Hash as arguments of a method call

Re: Hash as arguments of a method call

Re: Hash as arguments of a method call

Re: Hash as arguments of a method call

Re: Hash as arguments of a method call