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Constants
| APP_PATH | = | File.expand_path("test/dummy/config/application", ENGINE_ROOT) |
Instance Public methods
acts_like?(duck)Link
Provides a way to check whether some class acts like some other class based on the existence of an appropriately-named marker method.
A class that provides the same interface asSomeClass may define a marker method namedacts_like_some_class? to signal its compatibility to callers ofacts_like?(:some_class).
For example, Active Support extendsDate to define anacts_like_date? method, and extendsTime to defineacts_like_time?. As a result, developers can callx.acts_like?(:time) andx.acts_like?(:date) to test duck-type compatibility, and classes that are able to act likeTime can also define anacts_like_time? method to interoperate.
Note that the marker method is only expected to exist. It isn’t called, so its body or return value are irrelevant.
Example: A class that provides the same interface asString¶↑
This class may define:
classStringishdefacts_like_string?endend
Then client code can query for duck-type-safeness this way:
Stringish.new.acts_like?(:string)# => true
blank?()Link
An object is blank if it’s false, empty, or a whitespace string. For example,nil, ”, ‘ ’, [], {}, andfalse are all blank.
This simplifies
!address||address.empty?
to
address.blank?
@return [true, false]
deep_dup()Link
Returns a deep copy of object if it’s duplicable. If it’s not duplicable, returnsself.
object =Object.newdup =object.deep_dupdup.instance_variable_set(:@a,1)object.instance_variable_defined?(:@a)# => falsedup.instance_variable_defined?(:@a)# => true
duplicable?()Link
Can you safely dup this object?
False for method objects; true otherwise.
html_safe?()Link
in?(another_object)Link
Returns true if this object is included in the argument.
When argument is aRange, cover? is used to properly handle inclusion check within open ranges. Otherwise, argument must be any object which responds to include?. Usage:
characters = ["Konata","Kagami","Tsukasa"]"Konata".in?(characters)# => true
For nonRange arguments, this will throw anArgumentError if the argument doesn’t respond to include?.
# File activesupport/lib/active_support/core_ext/object/inclusion.rb, line 15defin?(another_object)caseanother_objectwhenRangeanother_object.cover?(self)elseanother_object.include?(self)endrescueNoMethodErrorraiseArgumentError.new("The parameter passed to #in? must respond to #include?")end
instance_values()Link
Returns a hash with string keys that maps instance variable names without “@” to their corresponding values.
classCdefinitialize(x,y)@x,@y =x,yendendC.new(0,1).instance_values# => {"x" => 0, "y" => 1}
instance_variable_names()Link
Returns an array of instance variable names as strings including “@”.
classCdefinitialize(x,y)@x,@y =x,yendendC.new(0,1).instance_variable_names# => ["@y", "@x"]
presence()Link
Returns the receiver if it’s present otherwise returnsnil.object.presence is equivalent to
object.present??object:nil
For example, something like
state =params[:state]ifparams[:state].present?country =params[:country]ifparams[:country].present?region =state||country||'US'
becomes
region =params[:state].presence||params[:country].presence||'US'
@return [Object]
presence_in(another_object)Link
Returns the receiver if it’s included in the argument otherwise returnsnil. Argument must be any object which responds to include?. Usage:
params[:bucket_type].presence_in%w( project calendar )
This will throw anArgumentError if the argument doesn’t respond to include?.
@return [Object]
present?()Link
An object is present if it’s not blank.
@return [true, false]
to_param()Link
Alias ofto_s.
to_query(key)Link
Converts an object into a string suitable for use as a URL query string, using the givenkey as the param name.
try(*args, &block)Link
Invokes the public method whose name goes as first argument just likepublic_send does, except that if the receiver does not respond to it the call returnsnil rather than raising an exception.
This method is defined to be able to write
@person.try(:name)
instead of
@person.nameif@person
try calls can be chained:
@person.try(:spouse).try(:name)
instead of
@person.spouse.nameif@person&&@person.spouse
try will also returnnil if the receiver does not respond to the method:
@person.try(:non_existing_method)# => nil
instead of
@person.non_existing_methodif@person.respond_to?(:non_existing_method)# => nil
try returnsnil when called onnil regardless of whether it responds to the method:
nil.try(:to_i)# => nil, rather than 0
Arguments and blocks are forwarded to the method if invoked:
@posts.try(:each_slice, 2) do |a, b| ...end
The number of arguments in the signature must match. If the object responds to the method the call is attempted andArgumentError is still raised in case of argument mismatch.
Iftry is called without arguments it yields the receiver to a given block unless it isnil:
@person.try do |p| ...end
You can also call try with a block without accepting an argument, and the block will be instance_eval’ed instead:
@person.try {upcase.truncate(50) }
Please also note thattry is defined onObject. Therefore, it won’t work with instances of classes that do not haveObject among their ancestors, like direct subclasses ofBasicObject.
Source:on GitHub
# File activesupport/lib/active_support/core_ext/object/try.rb, line 39try!(*args, &block)Link
Same astry, but raises aNoMethodError exception if the receiver is notnil and does not implement the tried method.
"a".try!(:upcase)# => "A"nil.try!(:upcase)# => nil123.try!(:upcase)# => NoMethodError: undefined method `upcase' for 123:Integer
Source:on GitHub
# File activesupport/lib/active_support/core_ext/object/try.rb, line 104with(**attributes)Link
Set and restore public attributes around a block.
client.timeout# => 5client.with(timeout:1)do|c|c.timeout# => 1endclient.timeout# => 5
The receiver is yielded to the provided block.
This method is a shorthand for the common begin/ensure pattern:
old_value =object.attributebeginobject.attribute =new_value# do thingsensureobject.attribute =old_valueend
It can be used on any object as long as both the reader and writer methods are public.
# File activesupport/lib/active_support/core_ext/object/with.rb, line 26defwith(**attributes)old_values = {}beginattributes.eachdo|key,value|old_values[key] =public_send(key)public_send("#{key}=",value)endyieldselfensureold_values.eachdo|key,old_value|public_send("#{key}=",old_value)endendend
with_options(options, &block)Link
An elegant way to factor duplication out of options passed to a series of method calls. Each method called in the block, with the block variable as the receiver, will have its options merged with the defaultoptionsHash orHash-like object provided. Each method called on the block variable must take an options hash as its final argument.
Withoutwith_options, this code contains duplication:
classAccount<ActiveRecord::Basehas_many:customers,dependent::destroyhas_many:products,dependent::destroyhas_many:invoices,dependent::destroyhas_many:expenses,dependent::destroyend
Usingwith_options, we can remove the duplication:
classAccount<ActiveRecord::Basewith_optionsdependent::destroydo|assoc|assoc.has_many:customersassoc.has_many:productsassoc.has_many:invoicesassoc.has_many:expensesendend
It can also be used with an explicit receiver:
I18n.with_optionslocale:user.locale,scope:'newsletter'do|i18n|subjecti18n.t:subjectbodyi18n.t:body,user_name:user.nameend
When you don’t pass an explicit receiver, it executes the whole block in merging options context:
classAccount<ActiveRecord::Basewith_optionsdependent::destroydohas_many:customershas_many:productshas_many:invoiceshas_many:expensesendend
with_options can also be nested since the call is forwarded to its receiver.
NOTE: Each nesting level will merge inherited defaults in addition to their own.
classPost<ActiveRecord::Basewith_optionsif::persisted?,length: {minimum:50 }dovalidates:content,if:-> {content.present? }endend
The code is equivalent to:
validates:content,length: {minimum:50 },if:-> {content.present? }
Hence the inherited default forif key is ignored.
NOTE: You cannot call class methods implicitly inside ofwith_options. You can access these methods using the class name instead:
classPhone<ActiveRecord::Baseenum:phone_number_type, {home:0,office:1,mobile:2 }with_optionspresence:truedovalidates:phone_number_type,inclusion: {in:Phone.phone_number_types.keys }endend
When the block argument is omitted, the decoratedObject instance is returned:
moduleMyStyledHelpersdefstyledwith_optionsstyle:"color: red;"endendstyled.link_to"I'm red","/"# => <a href="/" style="color: red;">I'm red</a>styled.button_tag"I'm red too!"# => <button style="color: red;">I'm red too!</button>
# File activesupport/lib/active_support/core_ext/object/with_options.rb, line 92defwith_options(options,&block)option_merger =ActiveSupport::OptionMerger.new(self,options)ifblockblock.arity.zero??option_merger.instance_eval(&block):block.call(option_merger)elseoption_mergerendend