XtSetLanguageProc

Before the initialization of the Xt Toolkit, applications should normally call the XtSetLanguageProc() function with one of the following functions:

XtSetLanguageProc (NULL, NULL, NULL)

The locale is not actually set until the toolkit is initialized (for example, by way of the XtAppInitialize() function). Therefore, the setlocale() function may be needed after the XtSetLanguageProc() function and the initializing of the toolkit (for example, if calling the catopen() function).

Resource databases are created in the current process locale. During display initialization prior to creating the per-screen resource database, the Intrinsics call to a specified application procedure to set the locale according to options found on the command line or in the per-display resource specifications.

The callout procedure provided by the application is of type XtLanguageProc, as in the following syntax:

typedef String(*XtLanguageProc)(displayID,languageID, clientdata);  
Display *displayID;  
String languageID;  
XtPointer clientdata;

displayID

Passes the display.

languageID

Passes the initial language value obtained from the command line or server per-display resource specifications.

clientdata

Passes the additional client data specified in the call to the XtSetLanguageProc() function.

The language procedure allows an application to set the locale to the value of the language resource determined by the XtDisplayInitialize() function. The function returns a new language string that is subsequently used by the XtDisplayInitialize() function to establish the path for loading resource files. This string is cached and is the locale of the display.

Initially, no language procedure is set by the intrinsics. To set the language procedure for use by the XtDisplayInitialize() function, use the XtSetLanguageProc() function:

XtLanguageProc XtSetLanguageProc(applicationcontext, procedure, clientdata) 
XtAppContext applicationcontext;  
XtLanguageProc procedure;  
XtPointer clientdata;

applicationcontext

Specifies the application context in which the language procedure is to be used or specifies a null value.

procedure

Specifies the language procedure.

clientdata

Specifies additional client data to be passed to the language procedure when it is called.

The XtSetLanguageProc() function sets the language procedure that is called from the XtDisplayInitialize() function for all subsequent displays initialized in the specified application context. If the applicationcontext parameter is null, the specified language procedure is registered in all application contexts created by the calling process, including any future application contexts that may be created. If the procedure parameter is null, a default language procedure is registered. The XtSetLanguageProc() function returns the previously registered language procedure. If a language procedure has not yet been registered, the return value is unspecified; but if this return value is used in a subsequent call to the XtSetLanguageProc() function, it causes the default language procedure to be registered.

The default language procedure does the following:

• Sets the locale according to the environment. On ANSI C-based systems, this is done by calling the setlocale (LC_ALL, "language") function. If an error is encountered, a warning message is issued with the XtWarning() function.

• Calls the XSupportsLocale() function to verify that the current locale is supported. If the locale is not supported, a warning message is issued with the XtWarning() function and the locale is set to "C".

• Calls the XSetLocaleModifiers() function specifying the empty string.

• Returns the value of the current locale. On ANSI C-based systems, this is the return value from a final call to the setlocale (LC_CTYPE, NULL) function.

A client can use this mechanism to establish a locale by calling the XtSetLanguageProc() function prior to the XtDisplayInitialize() function, as in the following example.

Widget top; 
XtSetLanguageProc(NULL, NULL, NULL);  
top = XtAppInitialize( ... ); 
...