Default (Compiler Magic Function)

From RemObjects Software

This is a Oxygene Language Feature topic
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default returns the default value of the specified type.
For Classes, this will be nil, for Records, this will be either 0 or for composit Records, this is an instance with all fields set to default.
You should be careful when assuming default values for Enums. When no 0 value has been defined, the underlying default value is still 0, but accessing it can result in an exception...

type
  MyRecordType = record
  public
    MyField : Integer
  end;
  MyEnumType1 = enum(One, Two, Three);
  MyEnumType2 = enum(None= 0, One, Two, Three);
...
var myInt    := default(Integer); // 0
var myString := default(String) // nil
var myRecord := default(MyRecordType); // myRecord.MyField is 0
var myEnum1  := default(MyEnumType1); // invalid value, it is 0 which is not defined
var myEnum2  := default(MyEnumType2); // None

method SomeClass.MyMethod<T>;
begin
  var myGeneric := default(T); // this is either nil, 0,
                               // or an empty record instance, depending on T

See Also

• Compiler Magic Functions
• Expressions

Product: RemObjects Oxygene (formerly known as Chrome)
Current version: 3.0 Previous Versions: 'Joyride' (2.0), 'Floorshow' (1.5), 'Adrenochrome' (1.0)

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