Functions

Functions are declared with function.

function Add(a : int, b : int) -> int:
    return a + b
endfunc

When there is no return value, omit ->.

function Log(value : int):
    // ...
endfunc

Declarations and Definitions

A function signature may be declared without a body.

function Add(a : int, b : int) -> int

The definition provides the body.

function Add(a : int, b : int) -> int:
    return a + b
endfunc

External functions are declarations connected to symbols outside DQ.

function printf(fmt : ^cchar, ...) -> int  [[external]]

Return Values

Functions with a return type have a built-in result variable.

function Add(a : int, b : int) -> int:
    result = a + b
endfunc

return value is also supported.

function Add(a : int, b : int) -> int:
    return a + b
endfunc

Parameters

The default parameter mode is by value.

function IncCopy(value : int) -> int:
    return value + 1
endfunc

Reference parameter modes are:

Mode	Meaning
ref	Read/write reference
refin	Read-only input reference
refout	Output reference
refnull	Nullable reference

function SetValue(value : ref int):
    value = 5
endfunc

function SumInput(value : refin int) -> int:
    return value + 1
endfunc

function MakeValue(value : refout int):
    value = 33
endfunc

function MaybeSet(value : refnull int):
    if &value == null:
        return
    endif
    value = 44
endfunc

refnull accepts null as an argument. Inside the function, &param == null tests whether a real storage location was supplied.

Default Arguments

Parameters may have default values.

function Repeat(text : strview, count : int = 1):
    // ...
endfunc

Default arguments are used when the caller omits the trailing argument.

Variable Arguments

External functions can declare C-style variable arguments with ....

function printf(fmt : ^cchar, ...) -> int  [[external]]

DQ library functions commonly use []anyvalue for type-checked variable value lists.

Print("{} {}", ["value", 123])

Function Overloading

Overloaded functions and methods must be marked with [[overload]].

function Print(value : int) [[overload]]:
    // ...
endfunc

function Print(value : strview) [[overload]]:
    // ...
endfunc

The overload set is selected by argument types.

Function References

Function reference types are declared with type.

type FUnary = function(value : int) -> int

function Inc(value : int) -> int:
    return value + 1
endfunc

var cb : FUnary = Inc
var value : int = cb(10)

Function references may be null and can be compared with null.

if cb != null:
    cb(1)
endif

Object method references add of object.

type FObjText = function(msg : cstring) of object

Special Functions

Names beginning with * are special-purpose functions.

*Main is the program entry point.

function *Main() -> int:
    return 0
endfunc

*ModuleInit is a module initialization function, called before the *Main()

var g_handler : OHandler = null

function *ModuleInit():
    g_handler = new OHandler()
endfunc

*Create is an object constructor and *Destroy is an object destructor.

object OThing:
    function *Create(value : int):
        // ...
    endfunc

    function *Destroy():
        // ...
    endfunc
endobj