module Puppet::Parser::Functions

A module for managing parser functions. Each specified function is added to a central module that then gets included into the Scope class.

@api public

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Constants

Environment

Public Class Methods

arity(name, environment = Puppet.lookup(:current_environment)) click to toggle source

Return the number of arguments a function expects.

@param [Symbol] name the function @param [Puppet::Node::Environment] environment The environment to find the function in @return [Integer] The arity of the function. See {newfunction} for

the meaning of negative values.

@api public

    # File lib/puppet/parser/functions.rb
297 def self.arity(name, environment = Puppet.lookup(:current_environment))
298   func = get_function(name, environment)
299   func ? func[:arity] : -1
300 end

autoloader() click to toggle source

Accessor for singleton autoloader

@api private

   # File lib/puppet/parser/functions.rb
70 def self.autoloader
71   @autoloader ||= AutoloaderDelegate.new
72 end

environment_module(env) click to toggle source

Get the module that functions are mixed into corresponding to an environment

@api private

    # File lib/puppet/parser/functions.rb
109 def self.environment_module(env)
110   @environment_module_lock.synchronize do
111     AnonymousModuleAdapter.adapt(env).module
112   end
113 end

function(name, environment = Puppet.lookup(:current_environment)) click to toggle source

Determine if a function is defined

@param [Symbol] name the function @param [Puppet::Node::Environment] environment the environment to find the function in

@return [Symbol, false] The name of the function if it's defined,

otherwise false.

@api public

    # File lib/puppet/parser/functions.rb
242 def self.function(name, environment = Puppet.lookup(:current_environment))
243   name = name.intern
244 
245   func = get_function(name, environment)
246   unless func
247     autoloader.delegatee.load(name, environment)
248     func = get_function(name, environment)
249   end
250 
251   if func
252     func[:name]
253   else
254     false
255   end
256 end

functiondocs(environment = Puppet.lookup(:current_environment)) click to toggle source

    # File lib/puppet/parser/functions.rb
258 def self.functiondocs(environment = Puppet.lookup(:current_environment))
259   autoloader.delegatee.loadall(environment)
260 
261   ret = String.new
262 
263   merged_functions(environment).sort { |a,b| a[0].to_s <=> b[0].to_s }.each do |name, hash|
264     ret << "#{name}\n#{"-" * name.to_s.length}\n"
265     if hash[:doc]
266       ret << Puppet::Util::Docs.scrub(hash[:doc])
267     else
268       ret << "Undocumented.\n"
269     end
270 
271     ret << "\n\n- *Type*: #{hash[:type]}\n\n"
272   end
273 
274   ret
275 end

newfunction(name, options = {}, &block) click to toggle source

Create a new Puppet DSL function.

**The {newfunction} method provides a public API.**

This method is used both internally inside of Puppet to define parser functions. For example, template() is defined in {file:lib/puppet/parser/functions/template.rb template.rb} using the {newfunction} method. Third party Puppet modules such as [stdlib](forge.puppetlabs.com/puppetlabs/stdlib) use this method to extend the behavior and functionality of Puppet.

See also [Docs: Custom Functions](puppet.com/docs/puppet/5.5/lang_write_functions_in_puppet.html)

@example Define a new Puppet DSL Function

>> Puppet::Parser::Functions.newfunction(:double, :arity => 1,
     :doc => "Doubles an object, typically a number or string.",
     :type => :rvalue) {|i| i[0]*2 }
=> {:arity=>1, :type=>:rvalue,
    :name=>"function_double",
    :doc=>"Doubles an object, typically a number or string."}

@example Invoke the double function from irb as is done in RSpec examples:

>> require 'puppet_spec/scope'
>> scope = PuppetSpec::Scope.create_test_scope_for_node('example')
=> Scope()
>> scope.function_double([2])
=> 4
>> scope.function_double([4])
=> 8
>> scope.function_double([])
ArgumentError: double(): Wrong number of arguments given (0 for 1)
>> scope.function_double([4,8])
ArgumentError: double(): Wrong number of arguments given (2 for 1)
>> scope.function_double(["hello"])
=> "hellohello"

@param [Symbol] name the name of the function represented as a ruby Symbol.

The {newfunction} method will define a Ruby method based on this name on
the parser scope instance.

@param [Proc] block the block provided to the {newfunction} method will be

executed when the Puppet DSL function is evaluated during catalog
compilation.  The arguments to the function will be passed as an array to
the first argument of the block.  The return value of the block will be
the return value of the Puppet DSL function for `:rvalue` functions.

@option options [:rvalue, :statement] :type (:statement) the type of function.

Either `:rvalue` for functions that return a value, or `:statement` for
functions that do not return a value.

@option options [String] :doc ('') the documentation for the function.

This string will be extracted by documentation generation tools.

@option options [Integer] :arity (-1) the

[arity](https://en.wikipedia.org/wiki/Arity) of the function.  When
specified as a positive integer the function is expected to receive
_exactly_ the specified number of arguments.  When specified as a
negative number, the function is expected to receive _at least_ the
absolute value of the specified number of arguments incremented by one.
For example, a function with an arity of `-4` is expected to receive at
minimum 3 arguments.  A function with the default arity of `-1` accepts
zero or more arguments.  A function with an arity of 2 must be provided
with exactly two arguments, no more and no less.  Added in Puppet 3.1.0.

@option options [Puppet::Node::Environment] :environment (nil) can

explicitly pass the environment we wanted the function added to.  Only used
to set logging functions in root environment

@return [Hash] describing the function.

@api public

    # File lib/puppet/parser/functions.rb
187 def self.newfunction(name, options = {}, &block)
188   name = name.intern
189   environment = options[:environment] || Puppet.lookup(:current_environment)
190 
191   Puppet.warning _("Overwriting previous definition for function %{name}") % { name: name } if get_function(name, environment)
192 
193   arity = options[:arity] || -1
194   ftype = options[:type] || :statement
195 
196   unless ftype == :statement or ftype == :rvalue
197     raise Puppet::DevError, _("Invalid statement type %{type}") % { type: ftype.inspect }
198   end
199 
200   # the block must be installed as a method because it may use "return",
201   # which is not allowed from procs.
202   real_fname = "real_function_#{name}"
203   environment_module(environment).send(:define_method, real_fname, &block)
204 
205   fname = "function_#{name}"
206   env_module = environment_module(environment)
207 
208   env_module.send(:define_method, fname) do |*args|
209     Puppet::Util::Profiler.profile(_("Called %{name}") % { name: name }, [:functions, name]) do
210       if args[0].is_a? Array
211         if arity >= 0 and args[0].size != arity
212           raise ArgumentError, _("%{name}(): Wrong number of arguments given (%{arg_count} for %{arity})") % { name: name, arg_count: args[0].size, arity: arity }
213         elsif arity < 0 and args[0].size < (arity+1).abs
214           raise ArgumentError, _("%{name}(): Wrong number of arguments given (%{arg_count} for minimum %{min_arg_count})") % { name: name, arg_count: args[0].size, min_arg_count: (arity+1).abs }
215         end
216         r = Puppet::Pops::Evaluator::Runtime3FunctionArgumentConverter.convert_return(self.send(real_fname, args[0]))
217         # avoid leaking aribtrary value if not being an rvalue function
218         options[:type] == :rvalue ? r : nil
219       else
220         raise ArgumentError, _("custom functions must be called with a single array that contains the arguments. For example, function_example([1]) instead of function_example(1)")
221       end
222     end
223   end
224 
225   func = {:arity => arity, :type => ftype, :name => fname}
226   func[:doc] = options[:doc] if options[:doc]
227 
228   env_module.add_function_info(name, func)
229 
230   func
231 end

reset() click to toggle source

Reset the list of loaded functions.

@api private

   # File lib/puppet/parser/functions.rb
22 def self.reset
23   # Runs a newfunction to create a function for each of the log levels
24   root_env = Puppet.lookup(:root_environment)
25   AnonymousModuleAdapter.clear(root_env)
26   Puppet::Util::Log.levels.each do |level|
27     newfunction(level,
28                 :environment => root_env,
29                 :doc => "Log a message on the server at level #{level}.") do |vals|
30       send(level, vals.join(" "))
31     end
32   end
33 end

rvalue?(name, environment = Puppet.lookup(:current_environment)) click to toggle source

Determine whether a given function returns a value.

@param [Symbol] name the function @param [Puppet::Node::Environment] environment The environment to find the function in @return [Boolean] whether it is an rvalue function

@api public

    # File lib/puppet/parser/functions.rb
284 def self.rvalue?(name, environment = Puppet.lookup(:current_environment))
285   func = get_function(name, environment)
286   func ? func[:type] == :rvalue : false
287 end

Private Class Methods

get_function(name, environment) click to toggle source

    # File lib/puppet/parser/functions.rb
312 def get_function(name, environment)
313   environment_module(environment).get_function_info(name.intern) || environment_module(Puppet.lookup(:root_environment)).get_function_info(name.intern)
314 end

merged_functions(environment) click to toggle source

    # File lib/puppet/parser/functions.rb
305 def merged_functions(environment)
306   root = environment_module(Puppet.lookup(:root_environment))
307   env = environment_module(environment)
308 
309   root.all_function_info.merge(env.all_function_info)
310 end