# Enumerated Types & Sets DWScript provides robust support for enumerations and sets, which are core features for writing clear and type-safe Pascal code. ## Enumerated Types An enumeration defines a set of named constants. DWScript supports three distinct styles of enumerations. ### 1. Classic Enumerations Symbols are globally scoped within the unit. This is the traditional Pascal style. ```pascal type TDirection = (North, East, South, West); // Type inference var d1 := North; // Explicit typing var d2 : TDirection := North; // OUTPUT NONE ``` ### 2. Scoped Enumerations Using the `enum` keyword requires you to prefix the values with the type name. This prevents name collisions. ```pascal type TStatus = enum (Ready, Busy, Error); // Type inference var s1 := TStatus.Ready; // Explicit typing var s2 : TStatus := TStatus.Ready; // OUTPUT NONE ``` ### 3. Flags (Bitmasks) Using the `flags` keyword automatically assigns power-of-two values (1, 2, 4, 8...). These are designed to be used with bitwise `or` to combine multiple values. ```pascal type TFileAccess = flags (Read, Write, Execute); // 1, 2, 4 // Type inference var access1 := TFileAccess.Read or TFileAccess.Write; // Explicit typing var access2 : TFileAccess := TFileAccess.Read or TFileAccess.Execute; // OUTPUT NONE ``` ## Sets Sets are collections of values from an ordinal type (usually an enumeration). A set can hold any combination of its base type's values, or be empty. A `set of TEnum` is stored efficiently as a bitfield. You can even cast a set to an `Integer` to see its underlying bitmask. ```pascal type TCards = (Club, Diamond, Heart, Spade); type THand = set of TCards; var hand: THand := [Club, Heart]; if Club in hand then PrintLn('You have a Club'); // Using ranges in sets var allMinors: THand := [Club..Diamond]; if Heart in [Club..Spade] then PrintLn('Hearts are in the range'); hand.Include(Spade); hand.Exclude(Club); if hand = [] then PrintLn('Empty hand'); // OUTPUT // You have a Club // Hearts are in the range ``` ## Built-in Methods Enumerations and sets provide several built-in methods for convenience: * **Enums**: * `TMyEnum.Low` and `TMyEnum.High` return the first and last values. * `TMyEnum.ByName('name')` returns the value matching the string. * `val.Name` returns the name of the enumeration value as a string. ```pascal // Enum ByName type TDirection = (North, East, South, West); var dir := TDirection.ByName('South'); PrintLn(dir.Name); // Set to Integer Cast type TCards = (Club, Diamond, Heart, Spade); type THand = set of TCards; var mySet : THand := [Club, Spade]; // 0th and 3rd bits PrintLn(Integer(mySet)); // OUTPUT // South // 9 ``` * **Sets**: * `mySet.Include(Value)` adds a value to the set. * `mySet.Exclude(Value)` removes a value from the set. * `mySet.Contains(Value)` is equivalent to the `in` operator.

Enumerated Types & Sets

DWScript provides robust support for enumerations and sets, which are core features for writing clear and type-safe Pascal code.

Enumerated Types

An enumeration defines a set of named constants. DWScript supports three distinct styles of enumerations.

1. Classic Enumerations

Symbols are globally scoped within the unit. This is the traditional Pascal style.

2. Scoped Enumerations

Using the enum keyword requires you to prefix the values with the type name. This prevents name collisions.

3. Flags (Bitmasks)

Using the flags keyword automatically assigns power-of-two values (1, 2, 4, 8...). These are designed to be used with bitwise or to combine multiple values.

Sets

Sets are collections of values from an ordinal type (usually an enumeration). A set can hold any combination of its base type's values, or be empty.

A set of TEnum is stored efficiently as a bitfield. You can even cast a set to an Integer to see its underlying bitmask.

Built-in Methods

Enumerations and sets provide several built-in methods for convenience:

• Enums:
  • TMyEnum.Low and TMyEnum.High return the first and last values.
  • TMyEnum.ByName('name') returns the value matching the string.
  • val.Name returns the name of the enumeration value as a string.

• Sets:
  • mySet.Include(Value) adds a value to the set.
  • mySet.Exclude(Value) removes a value from the set.
  • mySet.Contains(Value) is equivalent to the in operator.