One of the requirements of internationalizing programs (basic
commands and utilities inclusive) is that the messages displayed
on the output devices be in the language of the user. As these programs
may be used in many countries (international locales), the messages
must be translated into the various languages of these countries.
There are three sets of message extraction functions in the
desktop environment: XPG4 functions, Xlib functions, and DtMsgLog
functions.
XPG4/Universal UNIX Messaging
Functions |
 |
The XPG4 message facility consists of several components:
message source files, catalog generation facilities, and programming
interfaces. Following are the XPG4/Universal UNIXTM
message functions:
XPG4 Messaging
Examples |
|
There are three parts to this example which demonstrates how
to retrieve a message from a catalog. The first part shows the message
source file and the second part shows the method used to generate
the catalog file. The third part shows an example program using
this catalog.
The message catalog can be specified as follows:
example.msg file:
$quote "
$ every message catalog should have a beginning set number.
$set 1 This is the set 1 of messages
1 "Hello world\n"
2 "Good Morning\n"
3 "example: 1000.220 Read permission is denied for the file
%s.\n"
$set 2
1 "Howdy\n" |
Generation of Catalog File
This file is input to the gencat
utility to generate the message catalog example.cat
as follows:
gencat example.cat example.msg |
Accessing the Catalog in a
Program
#include <locale.h>
#include <nl_types.h>
char *MF_EXAMPLE = "example.cat"
main()
{
nl_catd catd;
int error;
(void)setlocale(LC_ALL, "");
catd = catopen(MF_EXAMPLE, 0);
/* Get the message number 1 from the first set.*/
printf( catgets(catd,1,1,"Hello world\n") );
/* Get the message number 1 from the second set.*/
printf( catgets(catd, 2, 1,"Howdy\n") );
/* Display an error message.*/
printf( catgets(catd, 1, 4,"example: 100.220
Permission is denied to read the file %s.\n"),
MF_EXAMPLE);
catclose(catd);
} |
Xlib Messaging Functions |
|
The following Xlib messaging functions
provide a similar input/output (I/O) operation to the resources.
They are described in X Window System, The Complete
Reference to Xlib, Xprotocol, ICCCM, XLFD - X Version 11, Release
6.
Xlib Message and Resource
Facilities |
|
Part of internationalizing a system environment, toolkit-based
application is not having any locale-specific data hardcoded within
the application source. One common locale-specific item is messages
(error and warning) returned by the application of the standard
I/O.
In general, for any error or warning messages to be displayed
to the user through a system environment toolkit widget or gadget,
externalize the messages through message catalogs.
For dialog messages to be displayed through a toolkit component,
externalize the messages through localized resource files. This
is done in the same way as localizing resources, such as the XmLabel
and XmPushButton
classes' XmNlabelString
resource or window titles.
For example, if a warning message is to be displayed through
an XmMessageBox
widget class, the XmNmessageString
resource cannot be hardcoded within the application source code.
Instead, the value of this resource must be retrieved from a message
catalog. For an internationalized application expected to run in
different locales, a distinct localized catalog must exist for each
of the locales to be supported. In this way, the application need
not be rebuilt.
Localized resource files can be put in the /usr/lib/X11/%L/appdefaults
subdirectories, or they can be pointed to by the XENVIRONMENT
environment variable. The %L variable is replaced
with the name of the locale used at run time.
Dt Messaging Functions |
|
The Dt messaging functions are DtMsgLogMessage(3),
DtMsgLogSetHandler(3),
and DtMsgLogOpenFile(3).
For more information, refer to Common Desktop Environment:
Programmer's Guide
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