Call a function: Difference between revisions

 

=={{header|Phix}}==

Phix has three kinds of routines: procedure, function, and type. A procedure does not return a value, whereas a function does.

A type is a specialised kind of function that permits declarations of instances which are automatically validated whenever they are changed, further a type routine always returns either true or false.

* Phix does not allow implicit discard of function results. The explicit discard statement takes the form

* This is in fact a simple contraction of standard multiple assigment (which can be nested as deeply as you like):

* Calling a function with no parameters still requires the "()" empty argument list.

* Optional arguments are denoted simply by the presence of a default, and must be grouped on the right:

* Sequence parameters can be of any length, which is another way to implement optional/variable number of arguments.

* Named arguments can be specified in any order, with an error if any non-optional parameters are missing:

* The programmer is free to use either positional parameters or named parameters, or a mixture of both (with positional parameters first).

The value of r_my_func can be passed as an argument to any routine, or stored in a table, and invoked in a similar fashion.<br>

Note however that for performance reasons some builtins do not have a proper routine_id; if you need one you must write a trivial one-line wrapper.<br>

* Partial application is usually achieved through a single variable-length "user_data" parameter within a call_func() expression.

* All arguments are passed by reference with copy-on-write semantics: to modify the value of a parameter you must both return and assign it, as in:

* Implicit forward calls are supported, as are optional explicit forward declarations, which can occasionally cure compilation error messages.