1. Function Definitions
2. Export
3. Function Properties
4. Aliases
5. Function Object

Function Definitions

function-definition:
   export type id ( parameter-list ) function-propertiesopt function-body

export:
  public
  package
  private

parameter-list:
   parameter
   parameter-list, parameter

function-body:
   { statement* }

function-properties:
   : function-property+

function-property:
  modify
  thiscall
  stdcall
  abstract
  null = expr
  widening converter
  inline
  encrypted
  nonfglue
  intrinsic
  referred
  require super
  pure
  no return

Example:
public int funcName(int a, int b) : abstract {
    statements
}
package void funcName(StrBuf buf) {
    statements
}

Export

• public
  Able to be invoked from anywhere.
• package
  Only able to invoked by code within the same directory (not including subdirectories).
• private
  Only able to invoked in the same file.

Function Properties

Function definitions can list various properties to request special treatment or signal aspects of their behavior.

• Use the inline property to request inlining of all calls to the function. Use with caution since overuse may lead to very large function bodies.

• Use the referred property to turn off all warnings that the function appears to be unused.

• The no return property signals to the compiler that the function never returns normally, or in other words that it always throws an exception.

• The pure property signals that the function is referentially transparent and that calls to it may be optimized or precomputed. A function is referentially transparent if the return value depends only on the parameters and not on any global state and the function lacks side effects. Only meant for the compiler developers.

Aliases

An alias can be used to make a short-hand to a function definition.

   function ( parameter-list ): type

This is often used with callback functions. For example, in cm/core/part/partHooks.cm :

/**
 * Raw hooks list.
 */
private alias completeListHook = function (Part[] list, Space space):Part[];

/**
 * Raw part hooks.
 */
private completeListHook{} completeListHooks : keep;


/**
 * Append a complete part list hook.
 */
public void appendRawPartListHook(completeListHook hook) {
    if (hook) {
        if (!completeListHooks) init completeListHooks();
        completeListHooks << hook;
    }
}

Function Object

In CM, any function can be cast into a Function object and vice versa:

private int normalFunction(int a, str b) { return a; }

{
    Function functionObject = function normalFunction;

    if (function(int, str):int backToNormal = functionObject.:function(int, str):int) {
        pln(backToNormal(5, ""));
    }
}