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#ifndef WITHOUT_NLS
catclose(catalog);
#endif
Reducing Strings to Localize
There is a good way of reducing the strings that need to be localized by using libc error messages. This is also useful to just avoid duplication and provide consistent error messages for the common errors that can be encountered by a great many of programs.
First, here is an example that does not use libc error messages:
#include err.h
...
if (!S_ISDIR(st.st_mode))
errx(1, "argument is not a directory");
This can be transformed to print an error message by reading `errno` and printing an error message accordingly:
#include err.h
#include errno.h
...
if (!S_ISDIR(st.st_mode)) {
errno = ENOTDIR;
err(1, NULL);
}
In this example, the custom string is eliminated, thus translators will have less work when localizing the program and users will see the usual "Not a directory" error message when they encounter this error. This message will probably seem more familiar to them. Please note that it was necessary to include [.filename]#errno.h# in order to directly access `errno`.
It is worth to note that there are cases when `errno` is set automatically by a preceding call, so it is not necessary to set it explicitly:
#include err.h
...
if ((p = malloc(size)) == NULL)
err(1, NULL);
Making use of [.filename]#bsd.nls.mk#
Using the catalog files requires few repeatable steps, such as compiling the catalogs and installing them to the proper location. In order to simplify this process even more, [.filename]#bsd.nls.mk# introduces some macros. It is not necessary to include [.filename]#bsd.nls.mk# explicitly, it is pulled in from the common Makefiles, such as [.filename]#bsd.prog.mk# or [.filename]#bsd.lib.mk#.
Usually it is enough to define `NLSNAME`, which should have the catalog name mentioned as the first argument of man:catopen[3] and list the catalog files in `NLS` without their `.msg` extension. Here is an example, which makes it possible to to disable NLS when used with the code examples before. The `WITHOUT_NLS` man:make[1] variable has to be defined in order to build the program without NLS support.
.if !defined(WITHOUT_NLS)
NLS= es_ES.ISO8859-1
NLS+= hu_HU.ISO8859-2
NLS+= pt_BR.ISO8859-1
.else
CFLAGS+= -DWITHOUT_NLS
.endif
Conventionally, the catalog files are placed under the [.filename]#nls# subdirectory and this is the default behavior of [.filename]#bsd.nls.mk#. It is possible, though to override the location of the catalogs with the `NLSSRCDIR` man:make[1] variable. The default name of the precompiled catalog files also follow the naming convention mentioned before. It can be overridden by setting the `NLSNAME` variable. There are other options to fine tune the processing of the catalog files but usually it is not needed, thus they are not described here. For further information on [.filename]#bsd.nls.mk#, please refer to the file itself, it is short and easy to understand.