From 72c578fd4b0b4a5a43e18594339ac4ff26c376dc Mon Sep 17 00:00:00 2001 From: Luca Falavigna Date: Sat, 2 Jan 2010 20:56:27 +0100 Subject: Imported Upstream version 1.2.0.d20091224 --- doc/user/libraries.in | 445 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 445 insertions(+) create mode 100644 doc/user/libraries.in (limited to 'doc/user/libraries.in') diff --git a/doc/user/libraries.in b/doc/user/libraries.in new file mode 100644 index 0000000..4cce091 --- /dev/null +++ b/doc/user/libraries.in @@ -0,0 +1,445 @@ + + + + + It's often useful to organize large software projects + by collecting parts of the software into one or more libraries. + &SCons; makes it easy to create libraries + and to use them in the programs. + + + +
+ Building Libraries + + + + You build your own libraries by specifying &b-link-Library; + instead of &b-link-Program;: + + + + + + Library('foo', ['f1.c', 'f2.c', 'f3.c']) + + + void f1() { printf("f1.c\n"); } + + + void f2() { printf("f2.c\n"); } + + + void f3() { printf("f3.c\n"); } + + + + + + &SCons; uses the appropriate library prefix and suffix for your system. + So on POSIX or Linux systems, + the above example would build as follows + (although &ranlib; may not be called on all systems): + + + + + scons -Q + + + + + On a Windows system, + a build of the above example would look like: + + + + + scons -Q + + + + + The rules for the target name of the library + are similar to those for programs: + if you don't explicitly specify a target library name, + &SCons; will deduce one from the + name of the first source file specified, + and &SCons; will add an appropriate + file prefix and suffix if you leave them off. + + + +
+ Building Libraries From Source Code or Object Files + + + + The previous example shows building a library from a + list of source files. + You can, however, also give the &b-link-Library; call + object files, + and it will correctly realize + In fact, you can arbitrarily mix source code files + and object files in the source list: + + + + + + Library('foo', ['f1.c', 'f2.o', 'f3.c', 'f4.o']) + + + void f1() { printf("f1.c\n"); } + + + object file + + + void f3() { printf("f3.c\n"); } + + + object file + + + + + + And SCons realizes that only the source code files + must be compiled into object files + before creating the final library: + + + + + scons -Q + + + + + Of course, in this example, the object files + must already exist for the build to succeed. + See , below, + for information about how you can + build object files explicitly + and include the built files in a library. + + + +
+ +
+ Building Static Libraries Explicitly: the &b-StaticLibrary; Builder + + + + The &b-link-Library; function builds a traditional static library. + If you want to be explicit about the type of library being built, + you can use the synonym &b-link-StaticLibrary; function + instead of &b-Library;: + + + + + + StaticLibrary('foo', ['f1.c', 'f2.c', 'f3.c']) + + + + + + There is no functional difference between the + &b-link-StaticLibrary; and &b-Library; functions. + + + +
+ +
+ Building Shared (DLL) Libraries: the &b-SharedLibrary; Builder + + + + If you want to build a shared library (on POSIX systems) + or a DLL file (on Windows systems), + you use the &b-link-SharedLibrary; function: + + + + + + SharedLibrary('foo', ['f1.c', 'f2.c', 'f3.c']) + + + void f1() { printf("f1.c\n"); } + + + void f2() { printf("f2.c\n"); } + + + void f3() { printf("f3.c\n"); } + + + + + + The output on POSIX: + + + + + scons -Q + + + + + And the output on Windows: + + + + + scons -Q + + + + + Notice again that &SCons; takes care of + building the output file correctly, + adding the -shared option + for a POSIX compilation, + and the /dll option on Windows. + + + +
+ +
+ +
+ Linking with Libraries + + + + Usually, you build a library + because you want to link it with one or more programs. + You link libraries with a program by specifying + the libraries in the &cv-link-LIBS; construction variable, + and by specifying the directory in which + the library will be found in the + &cv-link-LIBPATH; construction variable: + + + + + + + + Library('foo', ['f1.c', 'f2.c', 'f3.c']) + Program('prog.c', LIBS=['foo', 'bar'], LIBPATH='.') + + + int main() { printf("Hello, world!\n"); } + + + int main() { printf("Hello, world!\n"); } + + + int main() { printf("Hello, world!\n"); } + + + int main() { printf("Hello, world!\n"); } + + + + + + Notice, of course, that you don't need to specify a library + prefix (like lib) + or suffix (like .a or .lib). + &SCons; uses the correct prefix or suffix for the current system. + + + + + + On a POSIX or Linux system, + a build of the above example would look like: + + + + + scons -Q + + + + + On a Windows system, + a build of the above example would look like: + + + + + scons -Q + + + + + As usual, notice that &SCons; has taken care + of constructing the correct command lines + to link with the specified library on each system. + + + + + + Note also that, + if you only have a single library to link with, + you can specify the library name in single string, + instead of a Python list, + so that: + + + + + Program('prog.c', LIBS='foo', LIBPATH='.') + + + + + is equivalent to: + + + + + Program('prog.c', LIBS=['foo'], LIBPATH='.') + + + + + This is similar to the way that &SCons; + handles either a string or a list to + specify a single source file. + + + +
+ +
+ Finding Libraries: the &cv-LIBPATH; Construction Variable + + + + By default, the linker will only look in + certain system-defined directories for libraries. + &SCons; knows how to look for libraries + in directories that you specify with the + &cv-link-LIBPATH; construction variable. + &cv-LIBPATH; consists of a list of + directory names, like so: + + + + + + Program('prog.c', LIBS = 'm', + LIBPATH = ['/usr/lib', '/usr/local/lib']) + + + int main() { printf("prog.c\n"); } + + + + + + Using a Python list is preferred because it's portable + across systems. Alternatively, you could put all of + the directory names in a single string, separated by the + system-specific path separator character: + a colon on POSIX systems: + + + + + LIBPATH = '/usr/lib:/usr/local/lib' + + + + + or a semi-colon on Windows systems: + + + + + LIBPATH = 'C:\\lib;D:\\lib' + + + + + (Note that Python requires that the backslash + separators in a Windows path name + be escaped within strings.) + + + + + + When the linker is executed, + &SCons; will create appropriate flags + so that the linker will look for + libraries in the same directories as &SCons;. + So on a POSIX or Linux system, + a build of the above example would look like: + + + + + scons -Q + + + + + On a Windows system, + a build of the above example would look like: + + + + + scons -Q + + + + + + Note again that &SCons; has taken care of + the system-specific details of creating + the right command-line options. + + + +
-- cgit v1.2.3