- added environment variable overriding

[helm.git] / helm / ocaml / registry / helm_registry.mli

diff --git a/helm/ocaml/registry/helm_registry.mli b/helm/ocaml/registry/helm_registry.mli
index 02c0df76b8ec1bb4d3a4b3a5216c251644c69ec8..668525b86a13e49f034df503d782a0fba9915e34 100644 (file)
--- a/helm/ocaml/registry/helm_registry.mli
+++ b/helm/ocaml/registry/helm_registry.mli
@@ -25,17 +25,35 @@
 
 (** Configuration repository for HELM applications.
  *
- * key ::= path
- * path ::= component ( '.' component )*
- * component ::= ( alpha | num | '_' )+
+ * ++ Keys format ++
  *
- * Suggested usage <application>.<setting>:
- * e.g. gTopLevel.prooffile, http_getter.port, ...
+ *  key ::= path
+ *  path ::= component ( '.' component )*
+ *  component ::= ( lowercase_alpha | num | '_' )+
+ *  # with the only exception that sequences of '_' longer than 1 aren't valid
+ *  # components
  *
- * Configuration file example:
+ *  Suggested usage <application>.<setting>:
+ *   e.g. gTopLevel.prooffile, http_getter.port, ...
+ *
+ * ++ Configuration file example ++
  *
  *  gTopLevel.prooffile = "/home/zack/prooffile"
  *  http_getter.port = "58080"
+ *
+ * ++ Environment variable override ++
+ *
+ *  each key has an associated environment variable name. At runtime (i.e. when
+ *  "get" requests are performed) a variable with this name will be looked for,
+ *  if it's defined it will override the value present (or absent) in the
+ *  registry.
+ *  Environment variables are _not_ considered when saving the configuration to
+ *  a configuration file (via "save_to" function below) .
+ *
+ *  Mapping between keys and environment variables is as follows:
+ *  - the whole key is uppercased
+ *  - each "." is converted to "__"
+ *  E.g.: my.foo_ish.application -> MY__FOO_ISH__APPLICATION
  *)
 
   (** raised when a looked up key can't be found
@@ -54,8 +72,11 @@ exception Malformed_key of string
 
   (** raised when an error is encountered while parsing a configuration file
    * @param fname file name 
-   * @param lno line number *)
-exception Parse_error of string * int
+   * @param line line number
+   * @param col column number
+   * @param msg error description
+   *)
+exception Parse_error of string * int * int * string
 
   (** raised when a given <key,value> pair fails validity test(s)
    * @param pair <key,value> pair
@@ -66,6 +87,7 @@ exception Invalid_value of (string * string) * string
  * Using the functions below this module could be used as a repository of
  * key/value pairs *)
 
+  (** lookup key in registry with environment variable override *)
 val get: string -> string
 val set: key:string -> value:string -> unit
 
@@ -75,10 +97,13 @@ val set: key:string -> value:string -> unit
  * parsing of an integer number from ; strings list to the splitting at blanks
  * of it (heading and trailing blanks are removed before splitting) *)
 
+val get_string: string -> string  (* alias for bare "get" above *)
 val get_int: string -> int
 val get_float: string -> float
 val get_string_list: string -> string list
 
+  (* alias for bare "set" above *)
+val set_string: key:string -> value:string -> unit
 val set_int: key:string -> value:int -> unit
 val set_float: key:string -> value:float -> unit
 val set_string_list: key:string -> value:string list -> unit