How can I declare an array property?

user1730626 picture user1730626 · Oct 13, 2012 · Viewed 21.8k times · Source

I constructed class system

  TTableSpec=class(Tobject)
  private
    FName : string;
    FDescription : string;
    FCan_add : Boolean;
    FCan_edit : Boolean;
    FCan_delete : Boolean;
    FFields : array[1..100] of TFieldSpec;
  public
    property Name: String read FName;
    property Description: String read FDescription;
    property Can_add : Boolean read FCan_add;
    property Can_edit : Boolean read FCan_edit;
    property Can_delete : Boolean read FCan_delete;
    property Fields : array read FFields;
  end;

Thus in TableSpec Fields property shall be the list of fields (I used TFieldSpec array). How to organize the list of fields (using or without using an array) as as a result of compilation I receive an error

[Error] Objects.pas(97): Identifier expected but 'ARRAY' found
[Error] Objects.pas(97): READ or WRITE clause expected, but identifier 'FFields' found
[Error] Objects.pas(98): Type expected but 'END' found
[Hint] Objects.pas(90): Private symbol 'FFields' declared but never used
[Fatal Error] FirstTask.dpr(5): Could not compile used unit 'Objects.pas'

Answer

Andreas Rejbrand picture Andreas Rejbrand · Oct 13, 2012

Your line

property Fields : array read FFields;

is invalid syntax. It should be

property Fields[Index: Integer]: TFieldSpec read GetField;

where GetField is a (private) function that takes an integer (the Index) and returns the corresponding TFieldSpec, e.g.,

function TTableSpec.GetField(Index: Integer): TFieldSpec;
begin
  result := FFields[Index];
end;

See the documentation on array properties.