Rails - Feb 2007 - (style) does this make sense?

... or is this overly gratuitous use of the bang (!)... the documentation
says "potentially dangerous"... is raising an exception potentially
dangerous? or should i get rid of the bang?


def is_admin!(groupname=nil)
  unless logged_in?
    raise AdminAuthenticationError.new, "not logged in"
  end

  [...]
end

def is_admin?(groupname=nil)
  begin
    return is_admin!(groupname)
  rescue AdminAuthenticationError => detail
    logger.error "is_admin? failed: #{detail}"
    return false
  end
end


Thanks,
	Tyler

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> ... or is this overly gratuitous use of the bang (!)... the documentation
> says "potentially dangerous"... is raising an exception
potentially
> dangerous? or should i get rid of the bang?
>
>
> def is_admin!(groupname=nil)
>  unless logged_in?
>    raise AdminAuthenticationError.new, "not logged in"
>  end
>
>  [...]
> end
>
> def is_admin?(groupname=nil)
>  begin
>    return is_admin!(groupname)
>  rescue AdminAuthenticationError => detail
>    logger.error "is_admin? failed: #{detail}"
>    return false
>  end
> end
I''ve always thought of methods that end with ! as altering the object
that
calls them directly instead of returning a new value.  So in the above 
case, I''d say the is_admin! is uncalled for.

But that''s just me.

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>
> > def is_admin!(groupname=nil)
> >  unless logged_in?
> >    raise AdminAuthenticationError.new, "not logged in"
> >  end
> I''ve always thought of methods that end with ! as altering the
object that
> calls them directly instead of returning a new value.  So in the above
> case, I''d say the is_admin! is uncalled for.
>
> But that''s just me.
>
>
I agree... I think, in this particular case, what would make sense for a
bang would be something like
def is_admin!
  self.admin == true
end
Not that I''m sure that makes sense in your particular case, but I think
it
demonstrates the point.

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>>> def is_admin!(groupname=nil)
>>>  unless logged_in?
>>>    raise AdminAuthenticationError.new, "not logged in"
>>>  end
>> I''ve always thought of methods that end with ! as altering the
object that
>> calls them directly instead of returning a new value.  So in the above
>> case, I''d say the is_admin! is uncalled for.
>>
>> But that''s just me.
>>
>>
> I agree... I think, in this particular case, what would make sense for a
> bang would be something like
>
> def is_admin!
>  self.admin == true
> end
>
Really?  I would have thought this would make more sense...

def is_admin?
   self.admin == true
end

def is_admin!
   self.admin = true
end

The former is a question, the later is modifying self... although maybe 
that''s what you mean and just added an extra equal in there...




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On 2/23/07, Philip Hallstrom
<rails-SUcgGwS4C16SUMMaM/qcSw@public.gmane.org>
wrote:
>
> The former is a question, the later is modifying self... although maybe
> that''s what you mean and just added an extra equal in there...
>
Yep.

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Luke Ivers <technodolt-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> > The former is a question, the later is modifying self... although
maybe
> > that''s what you mean and just added an extra equal in
there...
> Yep.
  Well, since you guys are still talking about this, I might as well share
the whole method(s) with you. And yes, I got rid of the bang. :-)

  It''s for a website where users can save other users as contacts...
and
anybody user #1 (the "system user") saves as a contact is considered
an
administrator... You can categorize your contacts, and #1''s
categorizations
effectively become permissions...

ruby_code=<<_NEAT
  def is_admin(groupname=nil)
    unless logged_in?
      raise AdminAuthenticationError.new, "not logged in"
    end
    
    return true if current_user.id == 1
    
    system_user = User.find_by_id 1

    unless system_user.contacts.includes_user? current_user
      raise AdminAuthenticationError.new,
        "user is not a member of system_user''s contacts"
    end

    return true if groupname.nil?
    
    unless(
      group = system_user.contactgroups.select{ |g| g.name == groupname }.first
    )
      raise UserError.new, "Unknown admin group " + group + "
used in code!"
    end
    
    unless group.include? current_user
      raise AdminAuthenticationError.new,
        "user is not a member of system_user''s
''#{groupname}'' group"
    end
    
    return true
  end

  def is_admin?(groupname=nil)
    begin
      return is_admin(groupname)
    rescue AdminAuthenticationError => detail
      logger.error "is_admin? failed: #{detail}"
      return false
    end
  end

  class AuthenticationError < UserError
  end
  
  class AdminAuthenticationError < AuthenticationError
  end

_NEAT

  Cheers,
    Tyler


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Hi --

On Thu, 22 Feb 2007, Tyler MacDonald wrote:
>
> ... or is this overly gratuitous use of the bang (!)... the documentation
> says "potentially dangerous"... is raising an exception
potentially
> dangerous? or should i get rid of the bang?
>
>
> def is_admin!(groupname=nil)
>  unless logged_in?
>    raise AdminAuthenticationError.new, "not logged in"
>  end
You''re right that the ! means "potentially dangerous", and
does not
specifically mean "changes the receiver" (though that''s often
potentially dangerous, so a lot of methods that do it have the !).

But it''s normally used as one of a pair of methods, where one is
"dangerous" and one isn''t (map/map!, exit/exit!, etc.). 
Raising an
exception is not, per se, "dangerous", in this sense.


David

-- 
Q. What is THE Ruby book for Rails developers?
A. RUBY FOR RAILS by David A. Black (http://www.manning.com/black)
    (See what readers are saying!  http://www.rubypal.com/r4rrevs.pdf)
Q. Where can I get Ruby/Rails on-site training, consulting, coaching?
A. Ruby Power and Light, LLC (http://www.rubypal.com)

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HI --

On Fri, 23 Feb 2007, Philip Hallstrom wrote:
> Really?  I would have thought this would make more sense...
>
> def is_admin?
>   self.admin == true
> end
>
> def is_admin!
>   self.admin = true
> end
>
> The former is a question, the later is modifying self... although maybe
> that''s what you mean and just added an extra equal in there...
I don''t think there''s any advantage to writing a wrapper
method for
#admin=, though, since #admin= already exists and has clearer
semantics.


David

-- 
Q. What is THE Ruby book for Rails developers?
A. RUBY FOR RAILS by David A. Black (http://www.manning.com/black)
    (See what readers are saying!  http://www.rubypal.com/r4rrevs.pdf)
Q. Where can I get Ruby/Rails on-site training, consulting, coaching?
A. Ruby Power and Light, LLC (http://www.rubypal.com)

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in ruby, we usually get rid of the is_ prefix.

is_admin? *appears* redundant, why not just admin?

On Feb 24, 12:35 am, dbl...-TKXtfPMJ4Ozk1uMJSBkQmQ@public.gmane.org
wrote:
> HI --
>
> On Fri, 23 Feb 2007, Philip Hallstrom wrote:
> > Really?  I would have thought this would make more sense...
>
> > def is_admin?
> >   self.admin == true
> > end
>
> > def is_admin!
> >   self.admin = true
> > end
>
> > The former is a question, the later is modifying self... although
maybe
> > that''s what you mean and just added an extra equal in
there...
>
> I don''t think there''s any advantage to writing a wrapper
method for
> #admin=, though, since #admin= already exists and has clearer
> semantics.
>
> David
>
> --
> Q. What is THE Ruby book for Rails developers?
> A. RUBY FOR RAILS by David A. Black (http://www.manning.com/black)
>     (See what readers are saying!  http://www.rubypal.com/r4rrevs.pdf)
> Q. Where can I get Ruby/Rails on-site training, consulting, coaching?
> A. Ruby Power and Light, LLC (http://www.rubypal.com)

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But in Rails, don''t we usually use the is_ prefix to denote a boolean
attribute?

RSL

On 2/23/07, Evan <evansagge-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
>
>
> in ruby, we usually get rid of the is_ prefix.
>
> is_admin? *appears* redundant, why not just admin?
>
> On Feb 24, 12:35 am, dbl...-TKXtfPMJ4Ozk1uMJSBkQmQ@public.gmane.org wrote:
> > HI --
> >
> > On Fri, 23 Feb 2007, Philip Hallstrom wrote:
> > > Really?  I would have thought this would make more sense...
> >
> > > def is_admin?
> > >   self.admin == true
> > > end
> >
> > > def is_admin!
> > >   self.admin = true
> > > end
> >
> > > The former is a question, the later is modifying self... although
> maybe
> > > that''s what you mean and just added an extra equal in
there...
> >
> > I don''t think there''s any advantage to writing a
wrapper method for
> > #admin=, though, since #admin= already exists and has clearer
> > semantics.
> >
> > David
> >
> > --
> > Q. What is THE Ruby book for Rails developers?
> > A. RUBY FOR RAILS by David A. Black (http://www.manning.com/black)
> >     (See what readers are saying!  http://www.rubypal.com/r4rrevs.pdf)
> > Q. Where can I get Ruby/Rails on-site training, consulting, coaching?
> > A. Ruby Power and Light, LLC (http://www.rubypal.com)
>
>
> >
>
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Hey guys...

I just subscribed today and have read through the first couple dozen 
posts.  I''m VERY excited to jump into Rails development... but until I 
have a working development environment, it won''t happen.

I think I''ve gotten it installed and running on my Linux Fedora Core 6 
machine, and I can go to localhost:3000 with Mongrel running and get the 
"welcome" page.  But when I go to anywhere else, such as 
localhost:3000/category, to see the tutorial work I''ve done by reading 
the article at ONLamp.com, I get this in the browser:

Routing Error
no route found to match ''/category'' with
{:method=>"get}

In the development log, I see:
 
/usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/configurator.rb:270:in 
`each''
 
/usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/configurator.rb:270:in 
`run''
     /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/bin/mongrel_rails:127:in 
`run''
 
/usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/command.rb:211:in 
`run''
     /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/bin/mongrel_rails:243
     /usr/bin/mongrel_rails:16:in `load''
     /usr/bin/mongrel_rails:16


Rendering 
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/action_controller/templates/rescues/layout.rhtml
(404 Page Not Found)



--------------

I get the first set of errors often, but am not sure if they''re
serious.
  The Rendering error makes me wonder if Rails doesn''t know what
I''m
using for the web root.  What does Rails think is the web root by 
default?  I''ve been using /var/www/rails but have never set anything to
that value.

Thanks for any help!!

Rob

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Hey Rob,

From what I gather here, there''s something wrong with your Mongrel
setup.

Remember that the web root has to be set to the public folder within your
application, from there it gets the routes and everything to work properly.

Why not try just running script/server from the rails app directory...
should get you up and running easily.

On 2/24/07, RobG <sledder-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
>
>
>
> Hey guys...
>
> I just subscribed today and have read through the first couple dozen
> posts.  I''m VERY excited to jump into Rails development... but
until I
> have a working development environment, it won''t happen.
>
> I think I''ve gotten it installed and running on my Linux Fedora
Core 6
> machine, and I can go to localhost:3000 with Mongrel running and get the
> "welcome" page.  But when I go to anywhere else, such as
> localhost:3000/category, to see the tutorial work I''ve done by
reading
> the article at ONLamp.com, I get this in the browser:
>
> Routing Error
> no route found to match ''/category'' with
{:method=>"get}
>
> In the development log, I see:
>
> /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1
> /lib/mongrel/configurator.rb:270:in
> `each''
>
> /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1
> /lib/mongrel/configurator.rb:270:in
> `run''
>      /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/bin/mongrel_rails:127:in
> `run''
>
> /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/command.rb:211:in
> `run''
>      /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/bin/mongrel_rails:243
>      /usr/bin/mongrel_rails:16:in `load''
>      /usr/bin/mongrel_rails:16
>
>
> Rendering
> /usr/lib/ruby/gems/1.8/gems/actionpack-1.13.2
> /lib/action_controller/templates/rescues/layout.rhtml
> (404 Page Not Found)
>
>
>
> --------------
>
> I get the first set of errors often, but am not sure if they''re
serious.
>   The Rendering error makes me wonder if Rails doesn''t know what
I''m
> using for the web root.  What does Rails think is the web root by
> default?  I''ve been using /var/www/rails but have never set
anything to
> that value.
>
> Thanks for any help!!
>
> Rob
>
> >
>

-- 
Saludos,
Juan Roberto Morales
Gerente General
Digital Vision Studios

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Hey Juan...

That is how I''m running Mongrel... from script/server.  And I still get
those errors.

This is the tutorial I''ve been trying to make work:

http://www.onlamp.com/pub/a/onlamp/2006/12/14/revisiting-ruby-on-rails-revisited.html


Unfortunately, I know almost nothing about Rails, and little about Ruby. 
  I''ve played with Ruby and Watir a bit on Windows, but I want to get 
Rails running on a Linux machine if at all possible...

Rob




Juan Roberto Morales wrote:
> Hey Rob,
> 
>  From what I gather here, there''s something wrong with your
Mongrel setup.
> 
> Remember that the web root has to be set to the public folder within 
> your application, from there it gets the routes and everything to work 
> properly.
> 
> Why not try just running script/server from the rails app directory... 
> should get you up and running easily.
> 
> On 2/24/07, *RobG* < sledder-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
<mailto:sledder-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>> wrote:
> 
> 
> 
>     Hey guys...
> 
>     I just subscribed today and have read through the first couple dozen
>     posts.  I''m VERY excited to jump into Rails development... but
until I
>     have a working development environment, it won''t happen.
> 
>     I think I''ve gotten it installed and running on my Linux
Fedora Core 6
>     machine, and I can go to localhost:3000 with Mongrel running and get
the
>     "welcome" page.  But when I go to anywhere else, such as
>     localhost:3000/category, to see the tutorial work I''ve done by
reading
>     the article at ONLamp.com, I get this in the browser:
> 
>     Routing Error
>     no route found to match ''/category'' with
{:method=>"get}
> 
>     In the development log, I see:
> 
>     /usr/lib/ruby/gems/1.8/gems/mongrel-
>     1.0.1/lib/mongrel/configurator.rb:270:in
>     `each''
> 
>    
/usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/configurator.rb:270:in
>     `run''
>          /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/bin/mongrel_rails:127:in
>     `run''
> 
>     /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/command.rb:211:in
>     `run''
>          /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/bin/mongrel_rails:243
>          /usr/bin/mongrel_rails:16:in `load''
>          /usr/bin/mongrel_rails:16
> 
> 
>     Rendering
>    
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/action_controller/templates/rescues/layout.rhtml
>     (404 Page Not Found)
> 
> 
> 
>     --------------
> 
>     I get the first set of errors often, but am not sure if
they''re
>     serious.
>       The Rendering error makes me wonder if Rails doesn''t know
what I''m
>     using for the web root.  What does Rails think is the web root by
>     default?  I''ve been using /var/www/rails but have never set
anything to
>     that value.
> 
>     Thanks for any help!!
> 
>     Rob
> 
> 
> 
> 
> 
> 
> -- 
> Saludos,
> Juan Roberto Morales
> Gerente General
> Digital Vision Studios
> > 
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RobG wrote:
> Routing Error
> no route found to match ''/category'' with
{:method=>"get}
Are you sure you have a controller called "CategoryController"?

-- 
Posted via http://www.ruby-forum.com/.

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