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Contents
module Alf
module Types
#
# Attribute name.
#
# Attribute names are ruby symbols that match the following regular
# expression:
#
# /^[a-zA-Z0-9_]+[?!]?$/
#
# Example:
#
# AttrName["city"]
# # => :city
#
class AttrName < Symbol
extend Myrrha::Domain
class << self
# The domain predicate
PREDICATE = lambda{|s| s.to_s =~ /^[a-zA-Z0-9_]+[?!]?$/}
# Returns the domain predicate.
#
# @return [Proc] the domain predicate as a Proc obbject
def predicate
PREDICATE
end
# Coerces `arg` to an AttrName.
#
# All objects that respond to :to_sym and match PREDICATE are
# valid coercion arguments.
#
# @param [Object] arg and argument to coerce to an AttrName
# @return [AttrName] an AttrName instance
# @raise [ArgumentError] is the coercion fails
def coerce(arg)
if arg.respond_to?(:to_sym)
sym = arg.to_sym
return sym if self.===(sym)
end
raise ArgumentError, "Unable to coerce `#{arg.inspect}` to AttrName"
end
alias :[] :coerce
# Converts commandline arguments to an AttrName.
#
# This method requires `argv` to be either empty or a singleton array.
# When empty, `opts[:default]` is used. The value must be coercable
# with `coerce` for this method to suceed.
#
# @param [Array] argv commandline arguments
# @params [Hash] opts options (not used)
# @raise [ArgumentError] is the coercion fails
def from_argv(argv, opts = {})
raise ArgumentError if argv.size > 1
coerce(argv.first || opts[:default])
end
end
end # class AttrName
end # module Types
end # module Alf
Version data entries
5 entries across 5 versions & 1 rubygems