| 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.
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| Notes |
$ExtendedSyntax is equivalent to $X.
The default value is $ExtendedSyntax On
$ExtendedSyntax should be set just once in your code.
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| Related commands |
| $BoolEval |
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Whether to short cut and and or operations |
| $X |
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Controls some Pascal extension handling |
| Function |
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Defines a subroutine that returns a value |
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| Example code : Fail to compile code that does not assign a function result |
begin
// Set extended syntax off
{$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;
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| 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'
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| 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;
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| Show full unit code |
Code compiles OK and runs without doing anything.
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