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A duck-type assistant method. For example, Active Support extends Date to define an acts_like_date? method, and extends Time to define acts_like_time?. As a result, we can do “x.acts_like?(:time)” and “x.acts_like?(:date)” to do duck-type-safe comparisons, since classes that we want to act like Time simply need to define an acts_like_time? method.
An object is blank if it’s false, empty, or a whitespace string. For example, “”, “ “, nil, [], and {} are all blank.
This simplifies:
if address.nil? || address.empty?
…to:
if address.blank?
Can you safely dup this object?
False for nil, false, true, symbols, numbers, class and module objects; true otherwise.
Returns true if this object is included in the argument(s). Argument must be any object which responds to include? or optionally, multiple arguments can be passed in. Usage:
characters = ["Konata", "Kagami", "Tsukasa"]
"Konata".in?(characters) # => true
character = "Konata"
character.in?("Konata", "Kagami", "Tsukasa") # => true
This will throw an ArgumentError if a single argument is passed in and it doesn’t respond to include?.
# File activesupport/lib/active_support/core_ext/object/inclusion.rb, line 13 13: def in?(*args) 14: if args.length > 1 15: args.include? self 16: else 17: another_object = args.first 18: if another_object.respond_to? :include? 19: another_object.include? self 20: else 21: raise ArgumentError.new("The single parameter passed to #in? must respond to #include?") 22: end 23: end 24: end
# File railties/lib/rails/commands/benchmarker.rb, line 9 9: def options 10: options = {} 11: defaults = ActiveSupport::Testing::Performance::DEFAULTS 12: 13: OptionParser.new do |opt| 14: opt.banner = "Usage: rails benchmarker 'Ruby.code' 'Ruby.more_code' ... [OPTS]" 15: opt.on('-r', '--runs N', Numeric, 'Number of runs.', "Default: #{defaults[:runs]}") { |r| options[:runs] = r } 16: opt.on('-o', '--output PATH', String, 'Directory to use when writing the results.', "Default: #{defaults[:output]}") { |o| options[:output] = o } 17: opt.on('-m', '--metrics a,b,c', Array, 'Metrics to use.', "Default: #{defaults[:metrics].join(",")}") { |m| options[:metrics] = m.map(&:to_sym) } 18: opt.parse!(ARGV) 19: end 20: 21: options 22: end
# File railties/lib/rails/commands/profiler.rb, line 6 6: def options 7: options = {} 8: defaults = ActiveSupport::Testing::Performance::DEFAULTS 9: 10: OptionParser.new do |opt| 11: opt.banner = "Usage: rails benchmarker 'Ruby.code' 'Ruby.more_code' ... [OPTS]" 12: opt.on('-r', '--runs N', Numeric, 'Number of runs.', "Default: #{defaults[:runs]}") { |r| options[:runs] = r } 13: opt.on('-o', '--output PATH', String, 'Directory to use when writing the results.', "Default: #{defaults[:output]}") { |o| options[:output] = o } 14: opt.on('-m', '--metrics a,b,c', Array, 'Metrics to use.', "Default: #{defaults[:metrics].join(",")}") { |m| options[:metrics] = m.map(&:to_sym) } 15: opt.on('-f', '--formats x,y,z', Array, 'Formats to output to.', "Default: #{defaults[:formats].join(",")}") { |m| options[:formats] = m.map(&:to_sym) } 16: opt.parse!(ARGV) 17: end 18: 19: options 20: end
Returns object if it’s present? otherwise returns nil. object.presence is equivalent to object.present? ? object : nil.
This is handy for any representation of objects where blank is the same as not present at all. For example, this simplifies a common check for HTTP POST/query parameters:
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'
An object is present if it’s not blank?.
Dumps object in JSON (JavaScript Object Notation). See www.json.org for more info.
Alias of to_s.
Converts an object into a string suitable for use as a URL query string, using the given key as the param name.
Note: This method is defined as a default implementation for all Objects for Hash#to_query to work.
Invokes the method identified by the symbol method, passing it any arguments and/or the block specified, just like the regular Ruby Object#send does.
Unlike that method however, a NoMethodError exception will not be raised and nil will be returned instead, if the receiving object is a nil object or NilClass.
If try is called without a method to call, it will yield any given block with the object.
Please also note that try is defined on Object, therefore it won’t work with subclasses of BasicObject. For example, using try with SimpleDelegator will delegate try to target instead of calling it on delegator itself.
Examples
Without try
@person && @person.name
or
@person ? @person.name : nil
With try
@person.try(:name)
try also accepts arguments and/or a block, for the method it is trying
Person.try(:find, 1)
@people.try(:collect) {|p| p.name}
Without a method argument try will yield to the block unless the receiver is nil.
@person.try { |p| "#{p.first_name} #{p.last_name}" }
# File activesupport/lib/active_support/core_ext/uri.rb, line 13 13: def unescape(str, escaped = /%[a-fA-F\d]{2}/) 14: # TODO: Are we actually sure that ASCII == UTF-8? 15: # YK: My initial experiments say yes, but let's be sure please 16: enc = str.encoding 17: enc = Encoding::UTF_8 if enc == Encoding::US_ASCII 18: str.gsub(escaped) { [$&[1, 2].hex].pack('C') }.force_encoding(enc) 19: end
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
with_options can also be nested since the call is forwarded to its receiver. Each nesting level will merge inherited defaults in addition to their own.