10.5 Importing Projects

An immediate source of a project P may depend on source files that are neither immediate sources of P nor in the predefined library. To get this effect, P must import the projects that contain the needed source files.

       with "project1", "utilities.gpr";
       with "/namings/apex.gpr";
       project Main is
         ...

As can be seen in this example, the syntax for importing projects is similar to the syntax for importing compilation units in Ada. However, project files use literal strings instead of names, and the with clause identifies project files rather than packages.

Each literal string is the file name or path name (absolute or relative) of a project file. If a string is simply a file name, with no path, then its location is determined by the project path:

• If the environment variable ADA_PROJECT_PATH exists, then the project path includes all the directories in this environment variable, plus the directory of the project file.
• If the environment variable ADA_PROJECT_PATH does not exist, then the project path contains only one directory, namely the one where the project file is located.

If a relative pathname is used as in

       with "tests/proj";

then the path is relative to the directory where the importing project file is located. Any symbolic link will be fully resolved in the directory of the importing project file before the imported project file is looked up.

When the with'ed project file name does not have an extension, the default is .gpr. If a file with this extension is not found, then the file name as specified in the with clause (no extension) will be used. In the above example, if a file project1.gpr is found, then it will be used; otherwise, if a file project1 exists then it will be used; if neither file exists, this is an error.

A warning is issued if the name of the project file does not match the name of the project; this check is case insensitive.

Any source file that is an immediate source of the imported project can be used by the immediate sources of the importing project, and recursively. Thus if A imports B, and B imports C, the immediate sources of A may depend on the immediate sources of C, even if A does not import C explicitly. However, this is not recommended, because if and when B ceases to import C, some sources in A will no longer compile.

A side effect of this capability is that cyclic dependences are not permitted: if A imports B (directly or indirectly) then B is not allowed to import A.