From kevin.burge at systemware.com  Wed May  2 10:03:35 2007
From: kevin.burge at systemware.com (Kevin Burge)
Date: Wed, 02 May 2007 09:03:35 -0500
Subject: [Rant] gen Task's "needed" should override dependencies?
Message-ID: <20070502140240.F363F5240ABA@rubyforge.org>

I've found myself in the following situation more than once. Maybe it's 
just me.

Give the following Rantfile:

task :always do
  puts "always"
end

gen Task, :never => %w(always) do |t|
  t.needed { false }
  t.act {
    puts 'never'
  }
end

task :default => %w(never) do
  puts 'default'
end

Would you think that the task "never" should be made or not?  You'd 
think that "default" would only be made, since "never" is never 
needed... but because "always" is listed as a dependency of never, and 
always always needs to be made, never is made also, overriding needed 
being false.

Of course, in my code, what I meant it to say was:

"task never is only sometimes needed (like on this OS), and when it IS 
needed, it depends on these other tasks"

The work around is this:

task :always do
  puts "always"
end

gen Task, :never do |t|
  t.needed { false }
  t.act {
*    make "always"
*    puts 'never'
  }
end

task :default => %w(never) do
  puts 'default'
end

Am I the only one that sees this as a violation of POLS?

Thanks for the consideration,

Kevin
ps: if the test case doesn't make sense, change the name to the never 
task, to "sometimes", and replace "needed { false }" with "needed { 
some_condition }".


http://www.systemware.com/
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From kevin.burge at systemware.com  Wed May  2 10:48:08 2007
From: kevin.burge at systemware.com (Kevin Burge)
Date: Wed, 02 May 2007 09:48:08 -0500
Subject: [Rant] gen Task's "needed" should override dependencies?
In-Reply-To: <46389A37.80309@systemware.com>
References: <46389A37.80309@systemware.com>
Message-ID: <20070502144711.AAC97524096F@rubyforge.org>

I just realized that the 'make' work around below doesn't work, because 
the task made with "make", if it needs to be built, does not cause 
"this" task to be rebuilt.  Here is the alternate:

task :always do
  puts "always"
end

gen Task, :sometimes do |t|
  t.needed { *somecondition && rant.tasks['always'].needed? *}
  t.act {
*    make "always"
*    puts 'sometimes'
  }
end

task :default => %w(sometimes) do
  puts 'default'
end

Granted, in this example, "always" will always be needed.... I'm 
thinking of the scenario of when the dependent task might not always 
need to be made (like in my code).

Kevin Burge wrote:
> I've found myself in the following situation more than once. Maybe 
> it's just me.
>
> Give the following Rantfile:
>
> task :always do
>   puts "always"
> end
>
> gen Task, :never => %w(always) do |t|
>   t.needed { false }
>   t.act {
>     puts 'never'
>   }
> end
>
> task :default => %w(never) do
>   puts 'default'
> end
>
> Would you think that the task "never" should be made or not?  You'd 
> think that "default" would only be made, since "never" is never 
> needed... but because "always" is listed as a dependency of never, and 
> always always needs to be made, never is made also, overriding needed 
> being false.
>
> Of course, in my code, what I meant it to say was:
>
> "task never is only sometimes needed (like on this OS), and when it IS 
> needed, it depends on these other tasks"
>
> The work around is this:
>
> task :always do
>   puts "always"
> end
>
> gen Task, :never do |t|
>   t.needed { false }
>   t.act {
> *    make "always"
> *    puts 'never'
>   }
> end
>
> task :default => %w(never) do
>   puts 'default'
> end
>
> Am I the only one that sees this as a violation of POLS?
>
> Thanks for the consideration,
>
> Kevin
> ps: if the test case doesn't make sense, change the name to the never 
> task, to "sometimes", and replace "needed { false }" with "needed { 
> some_condition }".
>

http://www.systemware.com/
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From kevin.burge at systemware.com  Wed May  2 11:03:04 2007
From: kevin.burge at systemware.com (Kevin Burge)
Date: Wed, 02 May 2007 10:03:04 -0500
Subject: [Rant] gen Task's "needed" should override dependencies?
In-Reply-To: <20070502144711.AAC97524096F@rubyforge.org>
References: <46389A37.80309@systemware.com>
	<20070502144711.AAC97524096F@rubyforge.org>
Message-ID: <20070502150209.16957524096F@rubyforge.org>

I think I answered my own question:

"needed" is logically an "or" operation: if the task says it needs to be 
made, or any of it's dependencies need to be made, it needs to be made, 
and that's the way it should be.  I'm basically trying to make a task 
NOT a dependency in the "needed" clause, and that's not what "needed" is 
for.

Kevin Burge wrote:
> I just realized that the 'make' work around below doesn't work, 
> because the task made with "make", if it needs to be built, does not 
> cause "this" task to be rebuilt.  Here is the alternate:
>
> task :always do
>   puts "always"
> end
>
> gen Task, :sometimes do |t|
>   t.needed { *somecondition && rant.tasks['always'].needed? *}
>   t.act {
> *    make "always"
> *    puts 'sometimes'
>   }
> end
>
> task :default => %w(sometimes) do
>   puts 'default'
> end
>
> Granted, in this example, "always" will always be needed.... I'm 
> thinking of the scenario of when the dependent task might not always 
> need to be made (like in my code).
>

http://www.systemware.com/
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