Record

A mixin template for turning a struct into an immutable value type that automatically implements equality (==, !=), hashcode computation (toHash), stringification (toString), and mutation methods that create new copies with new values.

The purpose of this struct is act similarly to record types in functional programming languages like OCaml and Haskell.

Accepts an optional, boolean template parameter. When true, the mixin will generate a deconstruction method for use with <a href="/dext/dext/let">let</a>. Default is false.

All fields on the struct must start with an underscore and be non-public. Both are enforced with static asserts.

mixin template Record (

RecordParams params = RecordParams.init

) {

import std.traits : FieldTypeTuple, FieldNameTuple, staticMap;;

import std.format : format;;

this(FieldTypeTuple!(typeof(this)) args);

import dext.traits : asPointer;;

static if(params.enableLet)

void deconstruct(staticMap!(asPointer, FieldTypeTuple!(typeof(this))) ptrs);

bool opEquals(typeof(this) other);

static if(is(typeof(this) == class))

string toString();

static if(!(is(typeof(this) == class)))

string toString();

static if(is(typeof(this) == class))

size_t toHash();

static if(!(is(typeof(this) == class)))

size_t toHash();

}

Constructors

this this(FieldTypeTuple!(typeof(this)) args): Undocumented in source.

Members

Functions

deconstruct void deconstruct(staticMap!(asPointer, FieldTypeTuple!(typeof(this))) ptrs): Undocumented in source. Be warned that the author may not have intended to support it.
opEquals bool opEquals(typeof(this) other): Undocumented in source. Be warned that the author may not have intended to support it.
toHash size_t toHash(): Undocumented in source. Be warned that the author may not have intended to support it.
toHash size_t toHash(): Undocumented in source. Be warned that the author may not have intended to support it.
toString string toString(): Undocumented in source. Be warned that the author may not have intended to support it.
toString string toString(): Undocumented in source. Be warned that the author may not have intended to support it.

Examples

// define a point int 2D space
struct Point
{
    mixin Record!true;
    private int _x, _y;
}

auto a = Point( 3, 7 );
auto b = a.withX( 10 ); // creates a new copy of 'a' with a new 'x' value of 10 and the same 'y' value such that b == Point( 10, 7 )

// Euclidean distance
auto distance( in Point a, in Point b )
{
    import std.math : sqrt;

    return sqrt( ( a.x - b.x ) ^^ 2f + ( a.y - b.y ) ^^ 2f );
}

auto dist = distance( a, b );

Record

Constructors

Members

Functions

Examples

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