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Joshua Muheim

2009-Apr-19 21:51 UTC

cycle(...) - is there some sort of only_first_time(...)?

Hi all

The cycle() method is very handy in views. But is there some sort of
only_first_time() that returns the passed value only the first time it
is invoked within a view?

Thanks for help :-)
Josh
-- 
Posted via http://www.ruby-forum.com/.

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Rob Biedenharn

2009-Apr-19 22:38 UTC

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Re: cycle(...) - is there some sort of only_first_time(...)?

On Apr 19, 2009, at 5:51 PM, Joshua Muheim wrote:
>
> Hi all
>
> The cycle() method is very handy in views. But is there some sort of
> only_first_time() that returns the passed value only the first time it
> is invoked within a view?
>
> Thanks for help :-)
> Josh
> -- 
Just write one:

in a helper:
   def only_first_time(what)
     first_time = @previous_what.nil?
     @previous_what ||= what
     what if first_time
   end

in a view:
<ol>
   <% 5.times do |i| -%>
     <li>say <%= only_first_time(''once'')
%></li>
   <% end -%>
</ol>

the resulting HTML:
<ol>
  <li>say once</li>
  <li>say </li>
  <li>say </li>
  <li>say </li>
  <li>say </li>
  </ol>

-Rob
Rob Biedenharn		http://agileconsultingllc.com
Rob-xa9cJyRlE0mWcWVYNo9pwxS2lgjeYSpx@public.gmane.org


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Joshua Muheim

2009-Apr-19 22:52 UTC

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Re: cycle(...) - is there some sort of only_first_time(...)?

> Just write one:
> 
> in a helper:
>    def only_first_time(what)
>      first_time = @previous_what.nil?
>      @previous_what ||= what
>      what if first_time
>    end
Thanks, but that''s not very versatile. I could only use it once. AFAIK
I
can use cycle() wherever I want, so I''d like the helper to be somehow 
dependant from where it has been called. Is this possible?

Thanks
-- 
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Ryan Waldron

2009-Apr-20 00:27 UTC

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Re: cycle(...) - is there some sort of only_first_time(...)?

It might be instructive to look at the code for the cycle method.  It
actually creates an object and calls its to_s method each time you call
''cycle''.

You could do a similar thing.  Create a small class with a
''to_s'' method
that returns something the first time, but nothing thereafter.

class Once
  def initialize(first_value)
    @value = first_value
  end

  def reset
    @value = ''''
  end

  def to_s
    value = @value
    reset
    return value
  end
end

Stick that in lib/ or include it some other way. Then you can call cycle,
but pass your object as a single argument to cycle (cycle doesn''t
require
actually more than one param, though you could pass your object as both
params, or just pass it as the first param and '''' as the
second):

<% label_once = Once.new(''_bar'') %>

  <tr class=''foo<%= cycle(label_once) %>''>

You''ll get

  <tr class=''foo_bar''>
  ...
  <tr class=''foo''>
  ...
  <tr class=''foo''>

Might be a bit overkill, but kind of fun. :)

On Sun, Apr 19, 2009 at 5:52 PM, Joshua Muheim <
rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:
>
> > Just write one:
> >
> > in a helper:
> >    def only_first_time(what)
> >      first_time = @previous_what.nil?
> >      @previous_what ||= what
> >      what if first_time
> >    end
>
> Thanks, but that''s not very versatile. I could only use it once.
AFAIK I
> can use cycle() wherever I want, so I''d like the helper to be
somehow
> dependant from where it has been called. Is this possible?
>
> Thanks
> --
> Posted via http://www.ruby-forum.com/.
>
> >
>
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Jason Arora

2009-Apr-20 19:03 UTC

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Re: cycle(...) - is there some sort of only_first_time(...)?

I would prefer to use each_with_index:

@records.each_with_index do |r, i|
  "first record: #{r.name}" if i == 0
  "just another record: #{r.name}"
end

On Apr 19, 5:27 pm, Ryan Waldron
<r...-L2nCScK6t0HQT0dZR+AlfA@public.gmane.org>
wrote:> It might be instructive to look at the code for the cycle method.  It
> actually creates an object and calls its to_s method each time you call
> ''cycle''.
>
> You could do a similar thing.  Create a small class with a
''to_s'' method
> that returns something the first time, but nothing thereafter.
>
> class Once
>   def initialize(first_value)
>     @value = first_value
>   end
>
>   def reset
>     @value = ''''
>   end
>
>   def to_s
>     value = @value
>     reset
>     return value
>   end
> end
>
> Stick that in lib/ or include it some other way. Then you can call cycle,
> but pass your object as a single argument to cycle (cycle doesn''t
require
> actually more than one param, though you could pass your object as both
> params, or just pass it as the first param and '''' as the
second):
>
> <% label_once = Once.new(''_bar'') %>
>
>   <tr class=''foo<%= cycle(label_once) %>''>
>
> You''ll get
>
>   <tr class=''foo_bar''>
>   ...
>   <tr class=''foo''>
>   ...
>   <tr class=''foo''>
>
> Might be a bit overkill, but kind of fun. :)
>
> On Sun, Apr 19, 2009 at 5:52 PM, Joshua Muheim <
>
> rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:
>
> > > Just write one:
>
> > > in a helper:
> > >    def only_first_time(what)
> > >      first_time = @previous_what.nil?
> > >      @previous_what ||= what
> > >      what if first_time
> > >    end
>
> > Thanks, but that''s not very versatile. I could only use it
once. AFAIK I
> > can use cycle() wherever I want, so I''d like the helper to be
somehow
> > dependant from where it has been called. Is this possible?
>
> > Thanks
> > --
> > Posted viahttp://www.ruby-forum.com/.

Rails - Apr 2009 - cycle(...) - is there some sort of only_first_time(...)?

cycle(...) - is there some sort of only_first_time(...)?

Re: cycle(...) - is there some sort of only_first_time(...)?

Re: cycle(...) - is there some sort of only_first_time(...)?

Re: cycle(...) - is there some sort of only_first_time(...)?

Re: cycle(...) - is there some sort of only_first_time(...)?