11.13 Stand-alone Library Projects

A Stand-alone Library is a library that contains the necessary code to elaborate the Ada units that are included in the library. A Stand-alone Library is suitable to be used in an executable when the main is not in Ada. However, Stand-alone Libraries may also be used with an Ada main subprogram.

A Stand-alone Library Project is a Library Project where the library is a Stand-alone Library.

To be a Stand-alone Library Project, in addition to the two attributes that make a project a Library Project (Library_Name and Library_Dir, see Library Projects), the attribute Library_Interface must be defined.

        for Library_Dir use "lib_dir";
        for Library_Name use "dummy";
        for Library_Interface use ("int1", "int1.child");

Attribute Library_Interface has a nonempty string list value, each string in the list designating a unit contained in an immediate source of the project file.

When a Stand-alone Library is built, first the binder is invoked to build a package whose name depends on the library name (b~dummy.ads/b in the example above). This binder-generated package includes initialization and finalization procedures whose names depend on the library name (dummyinit and dummyfinal in the example above). The object corresponding to this package is included in the library.

A dynamic or relocatable Stand-alone Library is automatically initialized if automatic initialization of Stand-alone Libraries is supported on the platform and if attribute Library_Auto_Init is not specified or is specified with the value "true". A static Stand-alone Library is never automatically initialized.

Single string attribute Library_Auto_Init may be specified with only two possible values: "false" or "true" (case-insensitive). Specifying "false" for attribute Library_Auto_Init will prevent automatic initialization of dynamic or relocatable libraries.

When a non-automatically initialized Stand-alone Library is used in an executable, its initialization procedure must be called before any service of the library is used. When the main subprogram is in Ada, it may mean that the initialization procedure has to be called during elaboration of another package.

For a Stand-Alone Library, only the ALI files of the Interface Units (those that are listed in attribute Library_Interface) are copied to the Library Directory. As a consequence, only the Interface Units may be imported from Ada units outside of the library. If other units are imported, the binding phase will fail.

When a Stand-Alone Library is bound, the switches that are specified in the attribute Default_Switches ("Ada") in package Binder are used in the call to gnatbind.

The string list attribute Library_Options may be used to specified additional switches to the call to gcc to link the library.

The attribute Library_Src_Dir, may be specified for a Stand-Alone Library. Library_Src_Dir is a simple attribute that has a single string value. Its value must be the path (absolute or relative to the project directory) of an existing directory. This directory cannot be the object directory or one of the source directories, but it can be the same as the library directory. The sources of the Interface Units of the library, necessary to an Ada client of the library, will be copied to the designated directory, called Interface Copy directory. These sources includes the specs of the Interface Units, but they may also include bodies and subunits, when pragmas Inline or Inline_Always are used, or when there is a generic units in the spec. Before the sources are copied to the Interface Copy directory, an attempt is made to delete all files in the Interface Copy directory.