Mega Code Archive
$define - defines a compiler directive symbol - as used by ifdef
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{$Define Symbol}
Description
The $Define compiler directive defines a Symbol. By doing so, the symbol is now On.
When a symbol is on, $IfDef will compile conditional code, and $IfNDef will not.
When a symbol is off, $IfNDef will compile conditional code, and $IfDef will not.
Delphi provides some predefined symbols, such as Console that is on for a console application and off for a GUI application.
$Define is very useful when developing code, allowing various sections to be compiled when testing.
Related commands
$Else Starts the alternate section of an IfDef or IfNDef
$IfDef Executes code if a conditional symbol has been defined
$IfNDef Executes code if a conditional symbol has not been defined
$IfOpt Tests for the state of a Compiler directive
$IfOpt Tests for the state of a Compiler directive
$UnDef Undefines a compiler directive symbol - as used by IfDef
Example code : Setting up and using a test mode symbol
var
text : string;
begin
// Set our code into test mode
{$Define TESTMODE}
text := 'We are in test mode';
// Display the value of text if we are in test mode
{$IfDef TESTMODE}
ShowMessage('text = '+text);
{$EndIf}
// Switch off test mode
{$UnDef TESTMODE}
text := 'We are out of test mode';
// Display the value of text if we are in test mode
{$IfDef TESTMODE}
ShowMessage('text = '+text);
{$EndIf}
end;
We are in test mode
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