Server side state data, a.k.a eliom references
Module Eliom_reference
Module Eliom_reference : sig end
Server side state data, a.k.a Eliom references
=== Please read the {% <<a_manual chapter="server-state" | Eliom manual >> %} before this page to learn how server side state works. ===
type ('a, +'storage) eref'
Eliom references come in two flavors: they may be stored persistently or the may be volatile. The module Volatile allows creation of references which can be, get, set, modify, and unset volatile references through non-Lwt functions.
type 'a eref = ('a, [ `Persistent | `Volatile ]) eref'
The type of Eliom references whose content is of type 'a .
exception Eref_not_initialized
Exception raised when trying to access an eref that has not been initaliazed, when we don't want to initialize it.
val eref : scope:[< Eliom_common.all_scope ] -> ?secure:bool -> ?persistent:string -> 'a -> 'a eref
The function eref ~scope value creates an Eliom reference for the given scope and initialize it with value . See the Eliom manual for more information about .
Use the optional parameter ?persistent if you want the data to survive after relaunching the server. You must give an unique name to the table in which it will be stored on the hard disk (using Ocsipersist). Be very careful to use unique names, and to change the name if you change the type of the data, otherwise the server may crash (unsafe unmarshaling). This parameter has no effect for scope Eliom_common.request_scope .
Use the optional parameter ~secure:true if you want the data to be available only using HTTPS. This parameter has no effect for scopes Eliom_common.global_scope , Eliom_common.site_scope , and Eliom_common.request_scope .
Warning: Eliom references of scope Eliom_common.global_scope , Eliom_common.site_scope or Eliom_common.request_scope may be created at any time ; but for other scopes, they must be created when the site information is available to Eliom, that is, either during the initialization phase of the server (while reading the configuration file) or during a request. Otherwise, it will raise the exception Eliom_common.Eliom_site_information_not_available . If you are using static linking, you must delay the call to this function until the configuration file is read, using Eliom_service.register_eliom_module . Otherwise you will also get this exception.
val eref_from_fun : scope:[< Eliom_common.all_scope ] -> ?secure:bool -> ?persistent:string -> (unit -> 'a) -> 'a eref
The function eref_from_fun works like the above Eliom_reference.eref , but instead of providing a value for the initial content, a function f for creating the initial content is provided (cf. also Lazy.lazy_from_fun ).
In each scope, the function f is called for creating the value of the reference the first time the reference is read (by Eliom_reference.get ), if the value has not been set explicitly before (by Eliom_reference.set ); or if the reference was reset (by Eliom_reference.reset ) before.
val get : 'a eref -> 'a Lwt.t
The function get eref returns the current value of the Eliom reference eref .
Warning: this function cannot be used outside of a service handler when eref has been created with a scope different of Eliom_common.global_scope ; it can neither be used outside of an Eliom module when eref has been created with scope Eliom_common.site_scope
val set : 'a eref -> 'a -> unit Lwt.t
The function set eref v set v as current value of the Eliom reference eref .
Warning: this function could not be used outside af a service handler when eref has been created with a scope different of Eliom_common.global_scope ; it can neither be used outside of an Eliom module when eref has been created with scope Eliom_common.site_scope
val modify : 'a eref -> ('a -> 'a) -> unit Lwt.t
The function modify eref f modifies the content of the Eliom reference eref by applying the function f on it.
Warning: this function could not be used outside af a service handler when eref has been created with a scope different of Eliom_common.global_scope ; it can neither be used outside of an Eliom module when eref has been created with scope Eliom_common.site_scope
val unset : 'a eref -> unit Lwt.t
The function unset eref reset the content of the Eliom reference eref to its initial value.
Warning: this function could not be used outside af a service handler when eref has been created with a scope different of Eliom_common.global_scope ; it can neither be used outside of an Eliom module when eref has been created with scope Eliom_common.site_scope
module Volatile : sig end
Same functions as in Eliom_reference but a non-Lwt interface for non-persistent Eliom references.
module Ext : sig end