I found this macro code in Delphi/Pascal syntax but i can't use it! Does Delphi support macro codes like C/C++ or this macro is for another language such as Lazarus ???
The macro :
{$ifdef Profile}
{$define __TRACE__:= try }
{$define __END__:= finally ShowMessage('Hello !'); end;}
{$else}
{$define __TRACE__:= //}
{$define __END__:=}
{$endif}
I'm trying to use like this :
...
__TRACE__
// Somethings
__END__
...
I caught this compiler message :
[dcc32 Error] Unit1.pas(37): E2003 Undeclared identifier: '__TRACE__'
[dcc32 Error] Unit1.pas(38): E2066 Missing operator or semicolon
[dcc32 Error] Unit1.pas(39): E2003 Undeclared identifier: '__END__'
{Excuse me if my English is bad}
These are Free Pascal macros. There's nothing at all like this available for the Delphi compiler. Some options:
Use a logging framework (there are many good logging libraries available) to add trace debug facilities to the code. Frankly that would be a huge improvement on what is shown here.
Expand the code manually. That is each time you see __TRACE__ in the code, replace that with an inline $IFDEF. Not appealing at all.
Related
I'm trying to use generic records with RTTI, but ran into a problem with Type Info. Does anyone know why the following won't compile using Delphi 2010?
program GenericTypeInfo;
{$APPTYPE CONSOLE}
uses
TypInfo,
SysUtils;
type
TMyRec<T> = record
public
Value: T;
end;
TMyInt = TMyRec<Integer>;
TMyString = TMyRec<String>;
begin
try
Writeln(GetTypeName(TypeInfo(TMyRec<Integer>))); <--- This works fine
Writeln(GetTypeName(TypeInfo(TMyRec<String>))); <--- so does this
Writeln(GetTypeName(TypeInfo(TMyInt))); <--- BUT this won't compile
Writeln(GetTypeName(TypeInfo(TMyString))); <--- nor this!!
except
on E: Exception do
Writeln(E.ClassName, ': ', E.Message);
end;
Readln;
end.
The lines indicated above generate the following compiler errors:
[DCC Error] GenericTypeInfo.dpr(24): E2134 Type 'TMyInt' has no type info
[DCC Error] GenericTypeInfo.dpr(24): E2134 Type 'TMyString' has no type info
I can't what's the big difference between the 2? I admit I'm not a low-level expert, but why does the compiler treat this differently? I need it to work for the TMyInt and TMyString types.
Thanks for any help.
This is a bug in Delphi 2010 which has been fixed for XE and higher.
But there is a workaround.
This example works fine in XE2. (And XE as #StefanGlienke comments).
RTTI and generics in Delphi-2010 lacks implementation in many ways.
Since the interpretation of types is done by compiler magic, the workaround is to upgrade.
I need a bit of help; I'm helping a friend port a Delphi app built years back to newer versions of Windows, as it currently only runs on Windows 95.
The code utilises 3rd party libraries from Woll2Woll for DB operations.
One of these libraries generates the error E2003 Undeclared identifier: 'self'.
I've been through a number of sites via Google and with my limited knowledge of Delphi (stemming from my Pascal training about 12 years ago and extrapolating my slightly rusted PHP, BASH, ColdFusion and ASP coding skills), I've run into a brick wall - I'm strapped for time and can't make sense of the info I'm coming across on the web.
The problematic code segment is from the wwwQuery.pas file and looks like this:
{$ifdef wwDelphi3Up}
procedure TwwQuery.OpenCursor(InfoQuery: Boolean);
{$else}
procedure TwwQuery.OpenCursor;
{$endif}
begin
{$ifdef wwDelphi3Up}
inherited OpenCursor(InfoQuery);
{$else}
inherited OpenCursor;
{$endif}
//Modded by Arie
//wwSaveAnswerTable(self, Handle, FAnswerTable);
wwSaveAnswerTable(self, Handle, 'FAnswerTable');
end;
The precise error messages are:
[DCC Error] wwQuery.pas(243): E2003 Undeclared identifier: 'self'
[DCC Error] wwQuery.pas(244): E2029 '.' expected but ';' found
[DCC Fatal Error] wwcommon.pas(285): F2063 Could not compile used unit 'wwQuery.pas'
Line 243 is the 2nd last line, just above the end;
The wwSaveAnswerTable function looks like this:
Function wwSaveAnswerTable(ADataSet: TDBDataSet; AHandle: HDbiCur; tableName: string): boolean;
What must I change the Self parameter to, to stop the compile error?
Thanks a stack.
The problem is related to compiler define wwDelphi3Up or any related up in code.
As you see next error message: [DCC Error] wwQuery.pas(244): E2029 '.' expected but ';' found
Compiler expects end of program, and line wwSaveAnswerTable(self, Handle, 'FAnswerTable'); are not compiled inside OpenCursor method. That's why Self is not defined.
You don't need to change parameter, because for sure will affect functionality.
Try to compile it without defines, if you are not use an ancient version of Delphi:
procedure TwwQuery.OpenCursor(InfoQuery: Boolean);
begin
inherited OpenCursor(InfoQuery);
wwSaveAnswerTable(self, Handle, 'FAnswerTable'); // Here prob FAnswerTable without quotes
end;
For sake of example lets check for infamous TStrings.StrictDelimiter:
{$IF Declared(TStrings.StrictDelimiter)}
{$MESSAGE WARN 'Beware of TStrings.StrictDelimiter which is False by default!'}
{$IFEND}
However, Declared compiler intrinsic reports syntax error on conditional line: E2029 ')' expected but '.' found. (tested on XE)
For Delphi XE2 I'm using this :
{$IFDEF BDS9}
Result.VersionString := 'Delphi XE2 ' +
{$IF NOT DECLARED(Consts.SStyleFeatureNotSupported)}
'(original release version)'
{$ELSE} {$IF NOT DECLARED(FireMonkeyVersion)} // D2010 chokes when scope (FMX.Types) is mentioned!
'Update 1'
{$ELSE} {$IF NOT DECLARED(System.TestSSE)}
'Update 2'
{$ELSE}
'Update 3'
// TODO : Update this for any following update!
{$IFEND} {$IFEND} {$IFEND}
;
{$ELSE}
{$IFDEF BDS7}
Result.VersionString := 'Delphi 2010';
{$ELSE}
{$MESSAGE ERROR 'Extend this!'}
{$ENDIF}
{$ENDIF}
In other words : I test for the existence of symbols that are introduced since any particular delphi-version. The same construct can be used to set a variable or constant or compiler define, so further code can use these instead.
Note : I keep a backup around of the Source folder for all Delphi versions that I've had installed in the past few years. Putting these folders through a tool like BeyondCompare and browsing through the differencing files, will quickly give you a few symbols that you can test for....
Unfortunately this kind of expressions aren't supported, you have to know in which RTL / compiler version some feature was introduced and then use predefined conditional symbols like VER<nnn>, RTLVersion, CompilerVersion etc.
Consider the following snippet:
requires
designide,
rtl,
vcl,
{$IF RTLVersion < 19.0} // E2026 Constant expression expected
//{$IF CompilerVersion = 22.0} // same as above
vcljpg;
{$ELSE}
vclimg;
{$IFEND}
It seems to be absolutely syntactically correct. However, the compiler chokes on it and reports Constant expression expected. What really happens here?
Technical: currently tested on XE (15.0.3953.35171) only.
Of course, workaround suggestions are welcome too.
I found the same issue in the past even with delphi 2007. As workaround, I use a inc file with the conditional defines and then use {$IFDEF} instead of {$IF}
something like so
{$I MyDefines.INC}
requires
designide,
rtl,
vcl,
{$IFDEF DELPHI_XE_UP} //the DELPHI_XE_UP is defineed inside of MyDefines.INC
uNewlib;
{$ELSE}
uOldLib;
{$ENDIF}
package modules are different from program and library modules. They do not contain executable code and you cannot use units. Therefore, symbols like RTLVersion are simply not visible from a package file. Your only option is to use $IFDEF.
I'm convinced what i just found the cause. Consider the following:
{$IF not Declared(RTLVersion)}
{$MESSAGE WARN 'There is no RTL'}
{$IFEND}
{$IF not Declared(CompilerVersion)}
{$MESSAGE WARN 'nor are compiler intrinsics at all'}
{$IFEND}
{$IF not Declared(System)}
{$MESSAGE ERROR 'Because package not uses System implicitly'}
{$IFEND}
So, it appears to be what compiler behaves correctly, but issues a rather misleading (if not erroneous) message about symbol not being a constant expression, while symbol in question actually is undeclared!
Here is what I want to do. I have a project that must be compiled in some version of Delphi or later. I would like to use a conditional compiler directive to test the Delphi version, and then cause a custom compiler error to be generated with a custom message. Being able to generate a custom compiler warning or hint would also be adaquate if an error is not possible.
Sure, I could put some un-compilable giberish in the conditional code segment, and that's fine. But my question is "Can I generate, conditionally, a custom compiler error?"
Thank you Johan and Serg.
Here is the solution, and more details about the issue. I have an application that was originally built in Delphi 2007. It includes Internet Direct components to attach to a Web service. These use SSL. I recently upgraded my SSL libraries to a later version, and these don't play so well with the Delphi 2007 Indy components. I have now added the following compiler directives to ensure that this application will no longer be compiled with Delphi 2007 or earlier:
{$IF CompilerVersion <= 19.0} // Delphi 2007 = 19.0
{$MESSAGE Error 'This project must be compiled in Delphi 2009 or later'}
{$IFEND}
You can use:
{$Message HINT|WARN|ERROR|FATAL 'text string' }
{$MESSAGE 'Boo!'} emits a hint
{$Message Hint 'Feed the cats'} emits a hint
{$messaGe Warn 'Looks like rain.'} emits a warning
{$Message Error 'Not implemented'} emits an error, continues compiling
{$Message Fatal 'Bang. Yer dead.'} emits an error, terminates compiler
See: http://docs.embarcadero.com/products/rad_studio/delphiAndcpp2009/HelpUpdate2/EN/html/devcommon/compdirsmessagedirective_xml.html
This works in Delphi 6 and later.
Checking the Delphi version has become easy since CONDITIONALEXPRESSIONS directive was introduced in Delphi 6:
program requires2010;
{$APPTYPE CONSOLE}
{$IFDEF CONDITIONALEXPRESSIONS}
{$IF CompilerVersion >= 21.0} // 21.0 is Delphi 2010
{$DEFINE DELPHI2010}
{$IFEND}
{$ENDIF}
begin
{$IFNDEF DELPHI2010}
{$MESSAGE Fatal 'Wrong Delphi Version'}
{$ENDIF}
Writeln('Continued');
Readln;
end.