2.4. Create a Root Namespace

Normally all the bindings for a library are placed into a single root namespace. For example libfoo or foolib, would best be placed in a namespace called Foo. This follows the naming convention above. For example an initial VAPI would be:

namespace Foo {
    // bindings

The binding can then either be used in a Vala program by prefixing the namespace, e.g.:

void main () {

or bring the VAPI namespace into the scope of the file:

using Foo;

void main () {
    library_function ();

Namespaces also provide a convenient way to group functions. Typically, for GLib-based libraries, the x_y_foo patterns can be translated directly into a namespace as x.y.foo. Since most C libraries do not follow these conventions, things are slightly murkier. As general rules of thumb, try the following:

  • Move global variables, functions, constants, enums, flags, and delegate definitions into the class and struct definitions if they are clearly related only to that type. That is, it might make sense to move the enum FooOptions into class Foo as simply Options. Note that structs cannot contain enum, flag, or delegate definitions; only constants and static methods.

  • Use header files and directories as a guide. If the headers are stored as foo-2.0/db/{handle,transaction,row}.h or foo-2.0/db_{handle,transaction,row}.h or if foo-2.0/db.h contains definitions for foo_handle, foo_tx, and foo_row, there’s a good chance that creating a namespace Db is a logical grouping.

  • Create namespaces for large groups of related constants. Sometimes, constant collections cannot be converted to enums, in which case, grouping them into a namespace is much easier to manage.