GModule

GModule is a portable runtime dynamic loader provided by GLib’s libgmodule library. It offers a cross-platform API for loading shared libraries at runtime as modules, resolving symbols, and unloading modules. By wrapping platform-specific mechanisms such as dlopen and LoadLibrary, GModule enables applications to implement plug-in architectures without tying them to a single operating system interface.

The core concept is the GModule handle that represents a loaded module, along with a small set of functions to operate on it. Typical operations are opening a module file (g_module_open), resolving a symbol by name (g_module_symbol), and closing the module (g_module_close). A set of flags (GModuleFlags) controls how the module is bound (for example, eager or lazy binding) and how symbols are resolved; details vary by platform.

Usage typically involves a host application loading a plugin module, obtaining the address of a well-known entry point via g_module_symbol, casting it to the expected function pointer, and invoking it. The host can unload the module when the plugin is no longer needed. This approach supports runtime extensibility while keeping the host application lean and modular.

Origins and scope: GModule originated in the GNOME project as part of GLib’s support for dynamic plugins and is distributed as part of libgmodule (and GLib). It provides a consistent API across Unix-like systems and Windows. It is commonly used in GNOME applications and other GLib-based software that require optional, replaceable functionality.

Limitations and alternatives: dynamic loading introduces runtime dependencies and potential symbol resolution issues; careful interface design is required. Alternatives include static linking or other plugin frameworks. GLib’s GModule integrates with GLib’s error handling and type system and with GObject-based components.