command line arguments - OCaml illiterate in need of record manipulation assistance -

this little embarrassing i've been shown ocaml program know want cannot find documentation me write want in right syntax i've never used language before.

i made quite few working changes program , happens last change need make , cannot work out!

there record of sort (the syntax used had thrown me off) named caps_default:

let caps_default =     {         browsername = firefox ;         version = "" ;         platform = ;         username = "" ;         accesskey = "" ;         javascriptenabled = true     } ;; 

then these variables defined receive command line arguments:

exception incorrect_cmdline of string option ;;  let browser_name   = ref "" , hub_url_opt    = ref "" , target_url_opt = ref "" , xml_out_string = ref "" , user_name      = ref "" , access_key     = ref "" ;; 

i added 2 new arguments named 'username' , 'accesskey' , want add them "caps" record thing.

continuing on, here command line arguments parsed:

let (target_url, hub_url, caps, xml_out) =     try         parse_cmdline             [                 ( noshort , "browser-name" , none, (atmost_once browser_name   (incorrect_cmdline (some "browser-name"))) ) ;                 ( noshort , "hub-url"      , none, (atmost_once hub_url_opt    (incorrect_cmdline (some "hub-url"))) ) ;                 ( noshort , "target-url"   , none, (atmost_once target_url_opt (incorrect_cmdline (some "target-url"))) ) ;                 ( noshort , "xml-output"   , none, (atmost_once xml_out_string (incorrect_cmdline (some "xml-output"))) ) ;                 ( noshort , "username"     , none, (atmost_once user_name      (incorrect_cmdline (some "username"))) ) ;                 ( noshort , "accesskey"    , none, (atmost_once access_key     (incorrect_cmdline (some "accesskey"))) ) ;                 ( noshort , "help"         , (fun s -> raise (incorrect_cmdline none)) , none );             ]             ( fun x -> raise (incorrect_cmdline none)) ;         ignore (list.map                 (fun s -> if batstring.is_empty !s raise (incorrect_cmdline none) else () )                 [ browser_name ; hub_url_opt ; target_url_opt ] );         let target_url =             try             neturl.parse_url !target_url_opt                         neturl.malformed_url ->             raise (incorrect_cmdline (some ("invalid target url: " ^ !target_url_opt)))         , hub_url =             try             neturl.parse_url !hub_url_opt                         neturl.malformed_url ->             raise (incorrect_cmdline (some ("invalid hub url: " ^ !hub_url_opt)))         , xml_out =             if batstring.is_empty !xml_out_string             fun s -> ignore s             else             let chan = open_out !xml_out_string in             (fun xml ->             output_string chan (xml.to_string xml) ;             close_out chan )         (* continued below *) 

my desire take new command line argument options username , accesskey, assigned variables user_name , access_key, transmitted caps record defined in let assignments below:

        (* continued above *)         , caps =             { caps_default username = !user_name }   (* addition *)             { caps_default accesskey = !access_key } (* addition *)             match !browser_name   (* switch original , worked *)             | "firefox"   -> { caps_default browsername = firefox }             | "chrome"    -> { caps_default browsername = chrome }             | "html_unit" -> { caps_default browsername = htmlunit }             | "ie"        -> { caps_default browsername = internetexplorer }             | "iphone"    -> { caps_default browsername = iphone }             |  _        -> raise (incorrect_cmdline (some ("invalid browser name: " ^ !browser_name)))         in         (target_url, hub_url, caps, xml_out)             incorrect_cmdline arg ->             (match arg | none -> () | msg -> print_endline msg) ;             print_synopsis () ;             exit 48 ;; (* end of relevant code *) 

experimenting comment out original author's switch --browser-name , assign single value putting solemn line surrounded curly braces:

and caps=     { caps_default browsername = chrome } (* hard-coding chrome choice *) 

or

and caps=     { caps_default username = !user_name } (* sharing --username *) 

or

and caps=     { caps_default accesskey = !access_key } (* sharing --accesskey *) 

can point me in correct direction? want keep switch original author wrote transmit username , accesskey strings caps record on top of that. can change caps object later? can modify default_caps beforehand , copy caps?

this code run once per execution, modifying default_caps object of absolutely no concern, if it's not kosher so.

thanks assistance!

update

numerous mr. scofield's assistance far. curiously being met different error complaining can assume mis-match of type. here content of error:

file "tester.ml", line 110, characters 40-47: error: expression has type selenium.json_client.capabilities        expression expected of type selenium.json_client.browser 

line 110 is

{ caps_default browsername = browser; 

in mr. scofield's code snippet, 40-47 being browser.

the definition of default_caps's type capabilities such:

type capabilities =   {     browsername       : browser  ;     version           : string   ;     platform          : platform ;     javascriptenabled : bool     ;     username          : string   ;     accesskey         : string   ;   } 

and similarly, type browser:

type browser =   chrome | firefox | htmlunit | internetexplorer | iphone 

the mli (interface, correct?) definitions identical if important.

update part 2

minor correction needed simplify code this:

match !browser_name | "firefox"   -> { caps_default browsername = firefox } | "chrome"    -> { caps_default browsername = chrome } | "html_unit" -> { caps_default browsername = htmlunit } | "ie"        -> { caps_default browsername = internetexplorer } | "iphone"    -> { caps_default browsername = iphone } |  _        -> raise (incorrect_cmdline (some ("invalid browser name: " ^ !browser_name))) 

to this:

match !browser_name | "firefox"   -> firefox | "chrome"    -> chrome | "html_unit" -> htmlunit | "ie"        -> internetexplorer | "iphone"    -> iphone |  _        -> raise (incorrect_cmdline (some ("invalid browser name: " ^ !browser_name))) 

before continuing with:

in { caps_default browsername = browser;                     username    = !user_name;                     accesskey   = !access_key; } 

you might have learn little more ocaml want to :-)

the thing named caps_default record, i.e., has record type. you're going have find definition of record type , add new capabilities it.

update

ok, had record type fixed up. here's code

    , caps =         let browser =              match !browser_name             | "firefox"   ->  firefox             | "chrome"    ->  chrome             | "html_unit" ->  htmlunit             | "ie"        ->  internetexplorer             | "iphone"    ->  iphone             |  _        ->                 raise (incorrect_cmdline                    (some ("invalid browser name: " ^ !browser_name)))         in         { caps_default browsername = browser;                             username = !user_name;                             accesskey = !access_key;         }     in     (target_url, hub_url, caps, xml_out) 

(needless say, untested code.)

update 2

(fixed spelling of user_name, thanks.)