Class: Tanuki::Context

Inherits:
Object show all
Defined in:
lib/tanuki/context.rb

Overview

Tanuki::Context is used to create unique environments for each request. Child contexts inherit parent context entries and can override them without modifying the parent context. Use Tanuki::Context::child to create new contexts.

Class Method Summary collapse

Class Method Details

.child ⇒ Object

Creates and returns child context object. This object’s superclass is going to be current context class.



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# File 'lib/tanuki/context.rb', line 14

def child
  child = Class.new(self)
  child.instance_variable_set(:@_defined, {})
  child
end

.inspect ⇒ Object

Returns a printable version of Tanuki::Context, represented as a Hash. Can be used during development for inspection purposes. – When changing this method, remember to update ‘#+ 12’ to ‘defined.inspect` line number. This is required to avoid infinite recursion.



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# File 'lib/tanuki/context.rb', line 25

def inspect
  return to_s if caller.any? {|entry_point| entry_point =~ /\A#{__FILE__}:#{__LINE__ + 12}/}
  defined = {}
  ancestors.each do |ancestor|
    ancestor.instance_variable_get(:@_defined).each_key do |key|
      begin
        defined[key] ||= send(key)
      rescue ArgumentError
        defined[key] ||= method(key)
      end
    end
    break if ancestor.equal? Context
  end
  defined.inspect
end

.method_missing(sym, arg = nil) ⇒ Object

Allowes arbitary values to be assigned to context with a key= method. A reader in context object class is created for each assigned value.



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# File 'lib/tanuki/context.rb', line 43

def method_missing(sym, arg=nil)
  match = sym.to_s.match(/\A(?!(?:child|inspect|method_missing)=\Z)([^=]+)(=)?\Z/)
  raise "`#{sym}' method cannot be called for Context and its descendants" unless match
  defined = @_defined
  class << self; self; end.instance_eval do
    method_sym = match[1].to_sym
    if defined.include? method_sym
      undef_method method_sym
    else
      defined[method_sym] = nil
    end
    if arg.is_a? Proc
      define_method(method_sym, &arg)
    else
      define_method(method_sym) { arg }
    end
    return arg
  end if match[2]
  super
end

.new ⇒ Object

Disallow context instantiation



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# File 'lib/tanuki/context.rb', line 65

def new
  raise "contexts cannot be instantiated"
end