Syntax, identifiers and names

The CFEngine 3 language has a few simple rules:

• CFEngine built-in words, names of variables, bundles, body templates and classes may only contain the usual alphanumeric and underscore characters (a-zA-Z0-9_)
• All other 'literal' data must be quoted.

• Declarations of promise bundles in the form:

  bundle agent-type identifier { ... }

  Where agent-type is the CFEngine component responsible for maintaining the promise.

• Declarations of promise body-parts in the form:

  body constraint_type template_identifier { ... }

  matching and expanding on a reference inside a promise of the form constraint_type => template_identifier

• attribute expressions in the body of a promise take the form

  left-hand-side (CFEngine_word) => right-hand-side (user defined data).

  This can take several forms:

       cfengine_word => user_defined_template(parameters)
                        user_defined_template
                        builtin_function()
                        "quoted literal scalar"
                        { list }
  

  In each of these cases, the right hand side is a user choice.

  CFEngine uses many `constraint expressions' as part of the body of a promise. These take the form: left-hand-side (cfengine word) ‘=>’ right-hand-side (user defined data). This can take several forms:

  cfengine_word => user_defined_template(parameters)
      user_defined_template
      builtin_function()
      "quoted literal scalar"
      { list }
  

  In each of these cases, the right hand side is a user choice.