module Global

: sig

Mutable global variable.

Often in OCaml you want to have a global variable, which is mutable and uninitialized when declared. You can use a 'a option ref but this is not very convenient. The Global module provides functions to easily create and manipulate such variables.

type 'a t

Abstract type of a global

exception Global_not_initialized of string

Raised when a global variable is accessed without first having been assigned a value. The parameter contains the name of the global.

val empty : string -> 'a t

Returns an new named empty global. The name of the global can be any string. It identifies the global and makes debugging easier.

val name : 'a t -> string

Retrieve the name of a global.

val set : 'a t -> 'a -> unit

Set the global value contents.

val get : 'a t -> 'a

Get the global value contents - raise Global_not_initialized if not defined.

val undef : 'a t -> unit

Reset the global value contents to undefined.

val isdef : 'a t -> bool

Return true if the global value has been set.

val opt : 'a t -> 'a option

Return None if the global is undefined, else Some v where v is the current global value contents.

end