class Object
Public Instance Methods
An object is blank if it's false, empty, or a whitespace string. For example, nil
, '', ' ', [], {}, and false
are all blank.
This simplifies
!address || address.empty?
to
address.blank?
@return [true, false]
# File lib/sigterm_extensions/core_ext/object/blank.rb, line 16 def blank? respond_to?(:empty?) ? !!empty? : !self end
Can you safely dup this object?
False for method objects; true otherwise.
# File lib/sigterm_extensions/core_ext/object/duplicable.rb, line 24 def duplicable? true end
# File lib/sigterm_extensions/staging/boot/bundler_patch.rb, line 20 def enable_dual_booting Bundler::Definition.prepend(DefinitionPatch) Bundler::SharedHelpers.singleton_class.prepend(SharedHelpersPatch) end
Returns true if this object is included in the argument. Argument must be any object which responds to #include?
. Usage:
characters = ["Konata", "Kagami", "Tsukasa"] "Konata".in?(characters) # => true
This will throw an ArgumentError
if the argument doesn't respond to #include?
.
# File lib/sigterm_extensions/core_ext/object/inclusion.rb, line 10 def in?(another_object) another_object.include?(self) rescue NoMethodError raise ArgumentError.new("The parameter passed to #in? must respond to #include?") end
Returns a hash with string keys that maps instance variable names without “@” to their corresponding values.
class C def initialize(x, y) @x, @y = x, y end end C.new(0, 1).instance_values # => {"x" => 0, "y" => 1}
# File lib/sigterm_extensions/core_ext/object/instance_variables.rb, line 12 def instance_values Hash[instance_variables.map { |name| [name[1..-1], instance_variable_get(name)] }] end
Returns an array of instance variable names as strings including “@”.
class C def initialize(x, y) @x, @y = x, y end end C.new(0, 1).instance_variable_names # => ["@y", "@x"]
# File lib/sigterm_extensions/core_ext/object/instance_variables.rb, line 25 def instance_variable_names instance_variables.map(&:to_s) end
Return only the methods not present on basic objects
# File lib/sigterm_extensions/core_ext/object/methods.rb, line 57 def interesting_methods (self.methods - Object.new.methods).sort end
list methods which aren't in superclass
# File lib/sigterm_extensions/core_ext/object/methods.rb, line 29 def local_methods(obj = self) (obj.methods - obj.class.superclass.instance_methods).sort end
# File lib/sigterm_extensions/core_ext/object/methods.rb, line 33 def my_methods base_object = case self when Class then Class.new when Module then Module.new else Object.new end (methods - base_object.methods).sort end
Returns the receiver if it's present otherwise returns nil
. object.presence
is equivalent to
object.present? ? object : nil
For example, something like
state = params[:state] if params[:state].present? country = params[:country] if params[:country].present? region = state || country || 'US'
becomes
region = params[:state].presence || params[:country].presence || 'US'
@return [Object]
# File lib/sigterm_extensions/core_ext/object/blank.rb, line 43 def presence self if present? end
Returns the receiver if it's included in the argument otherwise returns nil
. Argument must be any object which responds to #include?
. Usage:
params[:bucket_type].presence_in %w( project calendar )
This will throw an ArgumentError
if the argument doesn't respond to #include?
.
@return [Object]
# File lib/sigterm_extensions/core_ext/object/inclusion.rb, line 24 def presence_in(another_object) in?(another_object) ? self : nil end
An object is present if it's not blank.
@return [true, false]
# File lib/sigterm_extensions/core_ext/object/blank.rb, line 23 def present? !blank? end
print documentation
ri 'Array#pop' Array.ri Array.ri :pop arr.ri :pop
# File lib/sigterm_extensions/core_ext/object/methods.rb, line 48 def ri(method = nil) unless method && method =~ /^[A-Z]/ # if class isn't specified klass = self.kind_of?(Class) ? name : self.class.name method = [klass, method].compact.join('#') end puts `ri '#{method}'` end
Invokes the public method whose name goes as first argument just like public_send
does, except that if the receiver does not respond to it the call returns nil
rather than raising an exception.
This method is defined to be able to write
@person.try(:name)
instead of
@person.name if @person
try
calls can be chained:
@person.try(:spouse).try(:name)
instead of
@person.spouse.name if @person && @person.spouse
try
will also return nil
if the receiver does not respond to the method:
@person.try(:non_existing_method) # => nil
instead of
@person.non_existing_method if @person.respond_to?(:non_existing_method) # => nil
try
returns nil
when called on nil
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 and ArgumentError
is still raised in case of argument mismatch.
If try
is called without arguments it yields the receiver to a given block unless it is nil
:
@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 that try
is defined on Object
. Therefore, it won't work with instances of classes that do not have Object
among their ancestors, like direct subclasses of BasicObject
.
# File lib/sigterm_extensions/core_ext/tryable.rb, line 32
Same as try
, but raises a NoMethodError
exception if the receiver is not nil
and does not implement the tried method.
"a".try!(:upcase) # => "A" nil.try!(:upcase) # => nil 123.try!(:upcase) # => NoMethodError: undefined method `upcase' for 123:Integer
# File lib/sigterm_extensions/core_ext/tryable.rb, line 97
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 default options
hash provided. Each method called on the block variable must take an options hash as its final argument.
Without with_options
, this code contains duplication:
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
Using with_options
, we can remove the duplication:
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
It can also be used with an explicit receiver:
I18n.with_options locale: user.locale, scope: 'newsletter' do |i18n| subject i18n.t :subject body i18n.t :body, user_name: user.name end
When you don't pass an explicit receiver, it executes the whole block in merging options context:
class Account < ActiveRecord::Base with_options dependent: :destroy do has_many :customers has_many :products has_many :invoices has_many :expenses end end
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.
class Post < ActiveRecord::Base with_options if: :persisted?, length: { minimum: 50 } do validates :content, if: -> { content.present? } end end
The code is equivalent to:
validates :content, length: { minimum: 50 }, if: -> { content.present? }
Hence the inherited default for if
key is ignored.
NOTE: You cannot call class methods implicitly inside of with_options. You can access these methods using the class name instead:
class Phone < ActiveRecord::Base enum phone_number_type: { home: 0, office: 1, mobile: 2 } with_options presence: true do validates :phone_number_type, inclusion: { in: Phone.phone_number_types.keys } end end
# File lib/sigterm_extensions/core_ext/object/with_options.rb, line 76 def with_options(options, &block) option_merger = SigtermExtensions::OptionMerger.new(self, options) block.arity.zero? ? option_merger.instance_eval(&block) : block.call(option_merger) end