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module Puppet
class ConstantAlreadyDefined < Error; end
class SubclassAlreadyDefined < Error; end
end
module Puppet::Util::ClassGen
include Puppet::Util::MethodHelper
include Puppet::Util
# Create a new subclass. Valid options are:
# * <tt>:array</tt>: An array of existing classes. If specified, the new
# class is added to this array.
# * <tt>:attributes</tt>: A hash of attributes to set before the block is
# evaluated.
# * <tt>:block</tt>: The block to evaluate in the context of the class.
# You can also just pass the block normally, but it will still be evaluated
# with <tt>class_eval</tt>.
# * <tt>:constant</tt>: What to set the constant as. Defaults to the
# capitalized name.
# * <tt>:hash</tt>: A hash of existing classes. If specified, the new
# class is added to this hash, and it is also used for overwrite tests.
# * <tt>:overwrite</tt>: Whether to overwrite an existing class.
# * <tt>:parent</tt>: The parent class for the generated class. Defaults to
# self.
# * <tt>:prefix</tt>: The constant prefix. Default to nothing; if specified,
# the capitalized name is appended and the result is set as the constant.
def genclass(name, options = {}, &block)
genthing(name, Class, options, block)
end
# Create a new module. Valid options are:
# * <tt>:array</tt>: An array of existing classes. If specified, the new
# class is added to this array.
# * <tt>:attributes</tt>: A hash of attributes to set before the block is
# evaluated.
# * <tt>:block</tt>: The block to evaluate in the context of the class.
# You can also just pass the block normally, but it will still be evaluated
# with <tt>class_eval</tt>.
# * <tt>:constant</tt>: What to set the constant as. Defaults to the
# capitalized name.
# * <tt>:hash</tt>: A hash of existing classes. If specified, the new
# class is added to this hash, and it is also used for overwrite tests.
# * <tt>:overwrite</tt>: Whether to overwrite an existing class.
# * <tt>:prefix</tt>: The constant prefix. Default to nothing; if specified,
# the capitalized name is appended and the result is set as the constant.
def genmodule(name, options = {}, &block)
genthing(name, Module, options, block)
end
# Remove an existing class
def rmclass(name, options)
options = symbolize_options(options)
const = genconst_string(name, options)
retval = false
if const_defined? const
remove_const(const)
retval = true
end
if hash = options[:hash] and hash.include? name
hash.delete(name)
retval = true
end
# Let them know whether we did actually delete a subclass.
return retval
end
private
# Generate the constant to create or remove.
def genconst_string(name, options)
unless const = options[:constant]
prefix = options[:prefix] || ""
const = prefix + name2const(name)
end
return const
end
# This does the actual work of creating our class or module. It's just a
# slightly abstract version of genclass.
def genthing(name, type, options, block)
options = symbolize_options(options)
name = symbolize(name.to_s.downcase)
if type == Module
#evalmethod = :module_eval
evalmethod = :class_eval
# Create the class, with the correct name.
klass = Module.new do
class << self
attr_reader :name
end
@name = name
end
else
options[:parent] ||= self
evalmethod = :class_eval
# Create the class, with the correct name.
klass = Class.new(options[:parent]) do
@name = name
end
end
# Create the constant as appropriation.
handleclassconst(klass, name, options)
# Initialize any necessary variables.
initclass(klass, options)
block ||= options[:block]
# Evaluate the passed block if there is one. This should usually
# define all of the work.
if block
klass.send(evalmethod, &block)
end
if klass.respond_to? :postinit
klass.postinit
end
# Store the class in hashes or arrays or whatever.
storeclass(klass, name, options)
return klass
end
# Handle the setting and/or removing of the associated constant.
def handleclassconst(klass, name, options)
const = genconst_string(name, options)
if const_defined? const
if options[:overwrite]
Puppet.info "Redefining %s in %s" % [name, self]
remove_const(const)
else
raise Puppet::ConstantAlreadyDefined,
"Class %s is already defined in %s" % [const, self]
end
end
const_set(const, klass)
return const
end
# Perform the initializations on the class.
def initclass(klass, options)
if klass.respond_to? :initvars
klass.initvars
end
if attrs = options[:attributes]
attrs.each do |param, value|
method = param.to_s + "="
if klass.respond_to? method
klass.send(method, value)
end
end
end
[:include, :extend].each do |method|
if set = options[method]
set = [set] unless set.is_a?(Array)
set.each do |mod|
klass.send(method, mod)
end
end
end
if klass.respond_to? :preinit
klass.preinit
end
end
# Convert our name to a constant.
def name2const(name)
name.to_s.capitalize
end
# Store the class in the appropriate places.
def storeclass(klass, klassname, options)
if hash = options[:hash]
if hash.include? klassname and ! options[:overwrite]
raise Puppet::SubclassAlreadyDefined,
"Already a generated class named %s" % klassname
end
hash[klassname] = klass
end
# If we were told to stick it in a hash, then do so
if array = options[:array]
if (klass.respond_to? :name and
array.find { |c| c.name == klassname } and
! options[:overwrite])
raise Puppet::SubclassAlreadyDefined,
"Already a generated class named %s" % klassname
end
array << klass
end
end
end
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