Externals

See "External Types".

Externals build on top of a standard Eiffel mechanism. This mechanism permits calling code in a language different from Eiffel.

You will find below the current list of external specifications supported by Liberty.

external "C"

This specification permits calling C code from Eiffel. This mechanism is described in Eiffel: The Language.

Some examples are available in the tutorial, tutorial/external/C.

This mechanism is only available with compile_to_c.

This mechanism has since been supplanted with plugins (see below).

external "C++"

This specification permits calling C++ code from Eiffel. This mechanism is described in Eiffel: The Language.

Some examples are available in the tutorial, tutorial/external/C++.

This mechanism is only available with compile_to_c.

This mechanism has since been supplanted with plugins (see below).

external "plug_in"

This specification is particularly utilized by the Liberty standard libraries. This form is preferred to external "C" and external "Java".

Examples are available throughout the standard library.

A dedicated page is devoted to this functionality.

external "built_in"

This specification is reserved for the compiler and its base libraries. It is not usable outside of very specific cases unique to compile_to_c and compile_to_jvm. These cases are the "building blocks" that produce specialized output code depending on the code generator being used.

For example, infix "#+" in the class INTEGER is directly translated in C by a +, and in Java by the iadd bytecode.

external types

A mechanism for embedding external types from the underlying language is being designed for the 2.4 release.

external "Java" - currently not supported

This specification would permit calling Java code from Eiffel. Some examples used to be available in the tutorial, tutorial/external/Java. This mechanism would only be available with compile_to_jvm, which currently is not supported.

This mechanism has since been supplanted with plugins (see below).