hey i have a method
def admin_login_required
username, passwd = get_auth_data
self.current_user ||= User.authenticate(username, passwd)
|| :false if username && passwd
logged_in? && authorized? ? true : access_denied
end
this is from an authentication plugin. i cant make sense of it, and
dont understand wot the ''||='' symbol does. i cant google for
it, cos
google strips the search for the symbol. can someone explain step by
step wot the function is doing ?
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On 5 Nov 2007, at 05:57, Chubbs wrote:> > hey i have a method > > def admin_login_required > username, passwd = get_auth_data > self.current_user ||= User.authenticate(username, passwd) > || :false if username && passwd > logged_in? && authorized? ? true : access_denied > end > > > this is from an authentication plugin. i cant make sense of it, and > dont understand wot the ''||='' symbol does. i cant google for it, cos > google strips the search for the symbol. can someone explain step by > step wot the function is doing ? >This is a ruby question so probably better suited to other places, but anyway, for most operators a op= b is the same as a = a op b So a ||= b is the same a = a || b Because of the way ruby evaluates these things, it means set a to b unless a is already set (in which case it won''t even evaluate b). Fred --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
Hi -- On Mon, 5 Nov 2007, Frederick Cheung wrote:> > > On 5 Nov 2007, at 05:57, Chubbs wrote: > >> >> hey i have a method >> >> def admin_login_required >> username, passwd = get_auth_data >> self.current_user ||= User.authenticate(username, passwd) >> || :false if username && passwd >> logged_in? && authorized? ? true : access_denied >> end >> >> >> this is from an authentication plugin. i cant make sense of it, and >> dont understand wot the ''||='' symbol does. i cant google for it, cos >> google strips the search for the symbol. can someone explain step by >> step wot the function is doing ? >> > > This is a ruby question so probably better suited to other places, but > anyway, > for most operators > a op= b is the same as a = a op b > So a ||= b is the same a = a || b > Because of the way ruby evaluates these things, it means set a to b > unless a is already set (in which case it won''t even evaluate b).There''s at least one edge-case which reveals that it a ||= b and a = a || b aren''t quite the same: irb(main):007:0> h = Hash.new(1) => {} irb(main):008:0> h[:x] ||= 2 => 1 irb(main):009:0> h => {} Here''s what happens with the plain || version: irb(main):010:0> h[:y] = h[:y] || 3 => 1 irb(main):011:0> h => {:y=>1} Matz had something to say about ||= at the Ruby Clinic that I conducted on Friday at RubyConf -- namely, that it''s better to think of it this way: x ||= y => x || (x = y) Translating my example that way produces the right result. David -- Upcoming training by David A. Black/Ruby Power and Light, LLC: * Advancing With Rails, Edison, NJ, November 6-9 * Advancing With Rails, Berlin, Germany, November 19-22 * Intro to Rails, London, UK, December 3-6 (by Skills Matter) See http://www.rubypal.com for details! --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
On 5 Nov 2007, at 10:36, David A. Black wrote:> > Matz had something to say about ||= at the Ruby Clinic that I > conducted on Friday at RubyConf -- namely, that it''s better to think > of it this way: > > x ||= y => x || (x = y) >You learn something everyday! Thanks for that. Fred --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---