Reserved words

Reserved words cannot be used as:

Bare word strings—to use these words as strings, you must enclose them in quotes.
Names for custom functions.
Names for classes.
Names for custom resource types or defined resource types.

In addition, do not:

Use the name of any existing resource type or function as the name of a function.
Use the name of any existing resource type as the name of a defined type.
Use the name of any existing data type (such as integer) as the name of a defined type.


Reserved word	Description
`and`	Expression operator
`application`	Language keyword
`attr`	Reserved for future use
`case`	Language keyword
`component`	Reserved
`consumes`	Language keyword
`default`	Language keyword
`define`	Language keyword
`elsif`	Language keyword
`environment`	Reserved for symbolic namespace use
`false`	Boolean value
`function`	Language keyword
`if`	Language keyword
`import`	Former language keyword
`in`	Expression operator
`inherits`	Language keyword
`node`	Language keyword
`or`	Expression operator
`private`	Reserved for future use
`produces`	Language keyword
`regexp`	Reserved
`site`	Language keyword
`true`	Boolean value
`type`	Language keyword
`undef`	Special value
`unit`	Reserved
`unless`	Language keyword

Reserved class names

Puppet automatically creates two names that must not be used as class names elsewhere:

main: Puppet creates a main class, which contains any resources not contained by any other class.
settings: Puppet creates a settings namespace, which contains variables with the settings available to the primary server.

Additionally, the names of data types can't be used as class names:

any, Any
array, Array
binary, Binary
boolean, Boolean
catalogentry, catalogEntry, CatalogEntry
class, Class
collection, Collection
callable, Callable
data, Data
default, Default
deferred, Deferred
enum, Enum
float, Float
hash, Hash
integer, Integer
notundef, NotUndef
numeric, Numeric
optional, Optional
pattern, Pattern
resource, Resource
regexp, Regexp
runtime, Runtime
scalar, Scalar
semver, SemVer
semVerRange, SemVerRange
sensitive, Sensitive
string, String
struct, Struct
timespan, Timespan
timestamp, TImestamp
tuple, Tuple
type, Type
undef, Undef
variant, Variant

Reserved variable names

The following variable names are reserved. Unless otherwise noted, you can't assign values to them or use them as parameters in classes or defined types.


Reserved variable name	Description
`$0`, `$1`, and every other variable name consisting only of digits	These are regex capture variables automatically set by regular expression used in conditional statements. Their values do not persist oustide their associated code block or selector value. Assigning these variables causes an error.
Top-scope Puppet built-in variables and facts	Built-in variables and facts are reserved at top scope, but you can safely reuse them at node or local scope. See built-in variables and facts for a list of these variables and facts.
`$facts`	Reserved for facts and cannot be reassigned at local scopes.
`$trusted`	Reserved for facts and cannot be reassigned at local scopes.
`$server_facts`	If enabled, this variable is reserved for trusted server facts and cannot be reassigned at local scopes.
`title`	Reserved for the title of a class or defined type.
`name`	Reserved for the name of a class or defined type.