diff options
Diffstat (limited to 'railties/guides/source/active_support_overview.textile')
| -rw-r--r-- | railties/guides/source/active_support_overview.textile | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/railties/guides/source/active_support_overview.textile b/railties/guides/source/active_support_overview.textile index 1537877c18..b6168f84da 100644 --- a/railties/guides/source/active_support_overview.textile +++ b/railties/guides/source/active_support_overview.textile @@ -277,6 +277,45 @@ The method +Hash#to_query+ accepts an optional namespace for the keys: # => "user%5Bid%5D=89&user%5Bname%5D=John+Smith" </ruby> +h4. +with_options+ + +The method +with_options+ provides a way to factor out common options in a series of method calls. + +Given a default options hash, +with_options+ yields a proxy object to a block. Within the block, methods called on the proxy are forwarded to the receiver with their options merged. For example, you get rid of the duplication in: + +<ruby> +class Account < ActiveRecord::Base + has_many :customers, :dependent => :destroy + has_many :products, :dependent => :destroy + has_many :invoices, :dependent => :destroy + has_many :expenses, :dependent => :destroy +end +</ruby> + +this way: + +<ruby> +class Account < ActiveRecord::Base + with_options :dependent => :destroy do |assoc| + assoc.has_many :customers + assoc.has_many :products + assoc.has_many :invoices + assoc.has_many :expenses + end +end +</ruby> + +That idiom may convey _grouping_ to the reader as well. For example, say you want to send a newsletter whose language depends on the user. Somewhere in the mailer you could group locale-dependent bits like this: + +<ruby> +I18n.with_options :locale => user.locale, :scope => "newsletter" do |i18n| + subject i18n.t :subject + body i18n.t :body, :user_name => user.name +end +</ruby> + +TIP: Since +with_options+ forwards calls to its receiver they can be nested. Each nesting level will merge inherited defaults in addition to their own. + h4. Silencing Warnings, Streams, and Exceptions The methods +silence_warnings+ and +enable_warnings+ change the value of +$VERBOSE+ accordingly for the duration of their block, and reset it afterwards: |