1 {$X-}
2 {$X+}
Description
The $X 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 $X. When +, 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 $X-, 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 $X+, you can also assign to the pseudo variable Result as in the example code.
3.Treating Char arrays as strings
With $X+, 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 $X+
$X should be set just once in your code.
Related commands
$BoolEval Whether to short cut and and or operations
$ExtendedSyntax Controls some Pascal extension handling
Function Defines a subroutine that returns a value
Example code : Fail to compile code that does not assign a function result
begin
// Set extended syntax off
{$X-}
// 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
{$X+}
// 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.