File: libtool.info,  Node: Dlopened modules,  Next: Using libltdl,  Prev: Inter-library dependencies,  Up: Top

10 Dlopened modules
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It can sometimes be confusing to discuss “dynamic linking”, because the
term is used to refer to two different concepts:

  1. Compiling and linking a program against a shared library, which is
     resolved automatically at run time by the dynamic linker.  In this
     process, dynamic linking is transparent to the application.

  2. The application calling functions such as ‘dlopen’ that load
     arbitrary, user-specified modules at runtime.  This type of dynamic
     linking is explicitly controlled by the application.

   To mitigate confusion, this manual refers to the second type of
dynamic linking as “dlopening” a module.

   The main benefit to dlopening object modules is the ability to access
compiled object code to extend your program, rather than using an
interpreted language.  In fact, dlopen calls are frequently used in
language interpreters to provide an efficient way to extend the
language.

   Libtool provides support for dlopened modules.  However, you should
indicate that your package is willing to use such support, by using the
‘LT_INIT’ option ‘dlopen’ in ‘configure.ac’.  If this option is not
given, libtool will assume no dlopening mechanism is available, and will
try to simulate it.

   This chapter discusses how you as a dlopen application developer
might use libtool to generate dlopen-accessible modules.

* Menu:

* Building modules::            Creating dlopenable objects and libraries.
* Dlpreopening::                Dlopening that works on static platforms.
* Linking with dlopened modules::  Using dlopenable modules in libraries.
* Finding the dlname::          Choosing the right file to ‘dlopen’.
* Dlopen issues::               Unresolved problems that need your attention.