18.5.1 Loader Mechanism
Since Libtool 1.4, libltdl has provided a generalized method for loading
modules, which can be extended by the user. libltdl has a default built
in list of module loading mechanisms, some of which are peculiar to a
given platform, others of which are more general. When the
`libltdl' subdirectory of a project is configured, the list is
narrowed to include only those mechanisms, or simply
loaders, which can work on the host architecture. When
`lt_dlopen' is called, the loaders in this list are tried, in
order, until the named module has loaded, or all of the loaders in the
list have been exhausted. The entries in the final list of loaders each
have a unique name, although there may be several candidate loaders for
a single name before the list is narrowed. For example, the
`dlopen' loader is implemented differently on BeOS and Solaris --
for a single host, there can be only one implementation of any named
loader. The name of a module loader is something entirely different to
the name of a loaded module, something that should become clearer as you
In addition to the loaders supplied with libltdl, your project can add
more loaders of its own. New loaders can be added to the end of the
existing list, or immediately before any other particular loader, thus
giving you complete control of the relative priorities of all of the
active loaders in your project.
In your module loading API, you might even support the dynamic
loading of user supplied loaders: that is your users would be able to
create dynamic modules which added more loading mechanisms to the
existing list of loaders!
Version 1.4 of Libtool has a default list that potentially contains an
implementation of the following loaders (assuming all are supported by
the host platform):
- If the named module was preloaded, use the preloaded symbol table for
- If the host machine has a native dynamic loader API use that to try
and load the module.
- If the host machine has GNU
dld(44), use that to try
and load the module.
Note that loader names with a `dl' prefix are reserved for future
use by Libtool, so you should choose something else for your own module
names to prevent a name clash with future Libtool releases.