DelphiBasics
$ExtendedSyntax
Compiler Directive
Controls some Pascal extension handling
{$ExtendedSyntax Off}
1
2 {$ExtendedSyntax On}
Description
The $ExtendedSyntax compiler directive determines whether Delphi includes a number of Pascal language extensions or not.
 
This affects three areas:
 
1.Treating functions as procedures
 
The example code shows the before and after effect of $ExtendedSyntax. When On, Delphi will allow a function result to be ignored - unassigned - thereby treating the function as if it were a procedure.
 
2.Using Result in functions
 
With $ExtendedSyntax Off, you must return a function value by assigning to the pseudo variable of the same name as the function. For example : function GetValue : Integer; begin   GetValue := 23; end;
 
With $ExtendedSyntax On, you can also assign to the pseudo variable Result as in the example code.
 
3.Treating Char arrays as strings
 
With $ExtendedSyntax On, a zero base array of Char variables can be assigned a string value. It can also be assigned from, as long as the array has a #0 value element to signify the string end.
Notes
$ExtendedSyntax is equivalent to $X.

The default value is $ExtendedSyntax On

$ExtendedSyntax should be set just once in your code.
Related commands
$BoolEvalWhether to short cut and and or operations
$XControls some Pascal extension handling
FunctionDefines a subroutine that returns a value
 Download this web site as a Windows program.




 
Example code : Fail to compile code that does not assign a function result
begin
  // Set extended syntax off
  {$ExtendedSyntax Off}

  // Call the GetValue function without assigning the result
  GetValue;
end;

// A function that simply returns the value 1
function TForm1.GetValue: Integer;
begin
  Result := 1;
end;
Show full unit code
  Compiltaion fails :
  
  [Error] Unit1.pas(39): Statement expected, but expression of type 'Integer' found
  [Error] Unit1.pas(45) Undeclared identifier: 'Result'
  [Fatal Error] Project1.dpr(5): Could not compile used unit 'Unit1.pas'
 
Example code : Code that does not assign a function result compiles OK
begin
  // Set extended syntax on
  {$ExtendedSyntax On}

  // Call the GetValue function without assigning the result
  GetValue;
end;

// A function that simply returns the value 1
function TForm1.GetValue: Integer;
begin
  Result := 1;
end;
Show full unit code
  Code compiles OK and runs without doing anything.
 
Delphi Programming © Neil Moffatt 2002 - 2022. All rights reserved.  |  Home Page