Method Syntax & Helpers

DWScript provides two powerful features to make your code more readable and to extend existing types without using inheritance.

Unified Method Syntax

Any function can be called as if it were a method of its first parameter. This leads to cleaner, more readable code that can be easily chained.

var s: String = '  hello  ';
// Standard style: UpperCase(Trim(s))
// Method style:
PrintLn(s.Trim.UpperCase); // "HELLO"

var i: Integer = 255;
PrintLn(i.ToHexString(4)); // Equivalent to IntToHex(i, 4)
Result
HELLO
00FF

This works because the compiler automatically maps the call x.Method(y) to Method(x, y) if a standalone function exists where the first parameter matches the type of x.

Built-in Type Helpers

Most basic types in DWScript have built-in helpers that provide convenient method aliases for standard library functions.

Type Common Methods Equivalent Function
Integer ToString, ToHexString, ToBin IntToStr, IntToHex, IntToBin
Float ToString, ToString(p) FloatToStr
String ToInteger, ToFloat, ToJSON, ToHtml StrToInt, StrToFloat, StrToJSON
Boolean ToString BoolToStr

Helpers

Helpers allow you to explicitly extend existing classes, records, and even basic types with new methods and properties.

Class Helpers

type
  TUser = class
    Name: String;
    constructor Create(n: String); begin Name := n; end;
  end;
type
  TUserHelper = class helper for TUser
    procedure Greet;
    begin
      PrintLn('Hello, ' + Name);
    end;
  end;

var u := new TUser('Alice');
u.Greet;
Result
Hello, Alice

Basic Type Helpers

You can extend primitive types like Integer, Float, or String to enable fluent syntax.

type
  TIntHelper = record helper for Integer
    function Squared: Integer;
    begin
      Result := Self * Self;
    end;
  end;

var n := 10;
PrintLn(n.Squared.ToString); // "100"
Result
100

Extension Methods

You can map existing functions as methods using the helper keyword in the function declaration.

function StringLength(s: String): Integer; helper Size;
begin
  Result := Length(s);
end;

var s := 'Hello';
PrintLn(s.Size.ToString); // 5
Result
5
← Metaclasses Memory Management →
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