Editing Object REXX (section)

=== C/C++ APIs ===
As classic Rexx, ooRexx includes APIs for extending Rexx with applications written in C and vice versa. This enables the creation of [[Callback (computer programming)|handlers]] for subcommands used in Rexx programs that run as application [[Macro (computer science)|macros]], external functions that allow a direct extension of the ooRexx function set and system functions that allow the behavior of the interpreter to be customized.<ref name=":8" />

With ooRexx 4.0.0 APIs have been introduced that allow C++ applications to extend ooRexx and vice versa. This includes handlers for methods and functions written in C++ that extend ooRexx, both packaged as external libraries. These are [[Dynamic-link library|dynamic link libraries]] on Windows or as [[Shared library|shared libraries]] on Unix-based systems. An external library can be loaded with the <code>::REQUIRES</code> directive or by using the <code>EXTERNAL</code> keyword instruction as part of a <code>::ROUTINE</code>, <code>::METHOD</code>, or <code>::ATTRIBUTE</code> directive.