\input texinfo @c -*-texinfo-*-
-@comment $Id: gnulib.texi,v 1.5 2004-09-28 22:58:00 eggert Exp $
+@comment $Id: gnulib.texi,v 1.10 2005-06-27 22:36:50 jas Exp $
@comment %**start of header
@setfilename gnulib.info
@settitle GNU Gnulib
@syncodeindex pg cp
@comment %**end of header
-@set UPDATED $Date: 2004-09-28 22:58:00 $
+@set UPDATED $Date: 2005-06-27 22:36:50 $
@copying
This manual is for GNU Gnulib (updated @value{UPDATED}),
which is a library of common routines intended to be shared at the
source level.
-Copyright @copyright{} 2004 Free Software Foundation, Inc.
+Copyright @copyright{} 2004, 2005 Free Software Foundation, Inc.
@quotation
Permission is granted to copy, distribute and/or modify this document
@node Gnulib
@chapter Gnulib
-This is not a real manual. It's just a place to store random notes
-until someone (you?) gets around to actually writing a manual.
+This manual contains some bare-bones documentation, but not much more.
+It's mostly been a place to store notes until someone (you?) gets
+around to writing a coherent manual.
Getting started:
* ctime::
* inet_ntoa::
* Out of memory handling::
+* Library version handling::
@end menu
@node Comments
any use. Thus, in theory, an application might not safely assume that
@code{_FOO_H} has not already been defined by a library. On the other
hand, using @code{FOO_H} will likely lead the higher risk of
-collisions with other symbols (e.g., @code{COFF_LONG_H} which is a CPP
-macro function). Your preference may depeend on whether you consider
+collisions with other symbols (e.g., @code{KEY_H}, @code{XK_H}, @code{BPF_H},
+which are CPP macro constants, or @code{COFF_LONG_H}, which is a CPP
+macro function). Your preference may depend on whether you consider
the header file under discussion as part of the application (which has
its own namespace for CPP symbols) or a supporting library (that
shouldn't interfere with the application's CPP symbol namespace).
your header file as something available for C programs only, or for C
and C++ programs alike.
+@subsection Include ordering
+
+When writing a gnulib module, or even in general, a good way to order
+the @samp{#include} directives is the following.
+
+@itemize
+@item First comes the #include "..." specifying the module being implemented.
+@item Then come all the #include <...> of system or system-replacement headers,
+in arbitrary order.
+@item Then come all the #include "..." of gnulib and private headers, in
+arbitrary order.
+@end itemize
+
@node ctime
@section ctime
@findex ctime
fail.
+@node Library version handling
+@section Library version handling
+
+The module ``check_version'' can be useful when your gnulib
+application is a system library. You will typically wrap the call to
+the @code{check_version} function through a library API, your library
+header file may contain:
+
+@example
+#define STRINGPREP_VERSION "0.5.18"
+...
+ extern const char *stringprep_check_version (const char *req_version);
+@end example
+
+The implementation of @code{stringprep_check_version} would simply
+pass on the call to @code{check_version}.
+
+There are two uses of the interface. The first is a way to provide
+for applications to find out the version number of the library it
+uses. The application may contain diagnostic code such as:
+
+@example
+ printf ("Stringprep version: header %s library %s",
+ STRINGPREP_VERSION,
+ stringprep_check_version (NULL));
+@end example
+
+Separating the library and header file version can be useful when
+searching for version mismatch related problems.
+
+The second uses is as a rudimentary test of proper library version, by
+making sure the application get a library version that is the same, or
+newer, than the header file used when building the application. This
+doesn't catch all problems, libraries may change backwards incompatibly
+in later versions, but enable applications to require a certain
+minimum version before it may proceed.
+
+Typical uses look like:
+
+@example
+ /* Check version of libgcrypt. */
+ if (!gcry_check_version (GCRYPT_VERSION))
+ die ("version mismatch\n");
+@end example
+
@node Invoking gnulib-tool
@chapter Invoking gnulib-tool
Creating ./m4/gnulib.m4...
Finished.
+You may need to add #include directives for the following .h files.
+ #include "strdup.h"
+
Don't forget to add "lib/Makefile"
to AC_CONFIG_FILES in "./configure.ac" and to mention
"lib" in SUBDIRS in some Makefile.am.
@code{--source-base=DIRECTORY} and @code{--m4-base=DIRECTORY}, or by
adding @samp{gl_SOURCE_BASE(DIRECTORY)} and
@samp{gl_M4_BASE(DIRECTORY)} to your @file{configure.ac}.
+Some modules also provide other files necessary
+for building. These files are copied into the directory specified
+by @samp{AC_CONFIG_AUX_DIR} in @file{configure.ac} or by the
+@code{--aux-dir=DIRECTORY} option. If neither is specified, the
+current directory is assumed.
+
+@code{gnulib-tool} can make symbolic links instead
+of copying the source files. Use the @code{--symbolic}
+(or @code{-s} for short) option to do this.
@code{gnulib-tool} will overwrite any pre-existing files, in
particular @file{Makefile.am}. Unfortunately, separating the
SUBDIRS += gl
@end example
-Finally, you have add C flags and LD flags, so that you can make use
+Finally, you have to add compiler and linker flags in the appropriate
+source directories, so that you can make use
of the gnulib library. For example:
@example
...
AM_CPPFLAGS = -I$(top_srcdir)/lib
...
-LIBADD = lib/libgnu.la
+LIBADD = lib/libgnu.a
...
@end example
projects / gnulib.git / blobdiff