Name
Type Keyword
Syntax
typeName=Type declaration; ... typeName= typeType declaration; typeName1=Name2; typeName= (Identifier, ...); typeName=Expr1..Expr2; typeName= ^Type; typeName= array[...] ofName; typeName= class ... end; typeName= class of ...; typeName= dispinterface ... end; typeName= file ofType; typeName= function ...; typeName= interface ... end; typeName= object ... end; typeName= procedure ...; typeName= record ... end; typeName= set ofOrdinal type;
Description
The type keyword begins a type declaration, as it
does in standard Pascal.
If the type declaration begins with another occurrence of the
type keyword, Delphi generates unique RTTI for the
type, even if the type is just a synonym for an existing type. It
also makes the type a distinct type with regard to
var parameters.
Tips and Tricks
A common convention in Delphi programs is to begin type names with the letter T, except for exception classes (which begin with E), interfaces (which begin with I), and pointer types (which begin with P).
A forward class declaration must be resolved in the same type block where it is declared. For example:
type
TExample = class; // forward declaration
TOther = class
procedure Example(E: TExample);
end;
// Full class declaration without using another "type" keyword,
// which starts a new type block.
TExample = class
procedure Example(Other: TOther);
end;A class declaration in the interface section of a unit must have definitions for all of the class’s non-abstract methods in the implementation section of the same unit.
Example
type
TSuit = (Diamond, Club, Heart, Spade);
PCard = ^TCard; // pointer to TCard;
TCard = record
Suit: TSuit;
Rank: 1..13;
end;
Deck = array[1..52] of TCard;
TSuits = set of TSuit;
TCardFunc = function(const Card: TCard): Integer;
TCardProc = procedure(const Card: TCard);
TCardMethodFunc = function(const Card: TCard): Integer of object;
TCardMethodProc = procedure(var Card: TCard) of object;
IGame = interface
['{6164F471-5E41-11D3-B1B6-00105AA9C2AD}']
procedure Play;
procedure Draw(var Card: TCard);
end;
TGame = class(TInterfacedObject, IGame)
public
procedure Play;
procedure Draw(var Card: TCard);
end;