module Eliom_reference:sig
..end
Please read the 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
. The default is false
, but this default
can be changed in configuration file (<securecookies value="true"/>
).
This option can be placed as global Eliom option (inside the <extension>
tag which is loading Eliom), or in the local configuration of one site
(inside the <eliom>
tag). But in the latter case,
it will only have effect on the actions performed after in the same <site>
(and NOT on the top-level instructions of the modules loaded before).
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.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
).
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
This module allows access to references for other groups, sessions, or client processes.