Need help! Writing dll.
lazarus / 16-Databases

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FreekNel · 2008-04-15 06:59

Hi people. Sorry for my english. I tried to write library which
executes basic buisnes-rules for my program. And I have a problem
which stops all process. For tests I write a simple library.

Code: [Select]
library lib_main;

{$mode delphi}{$H+}

uses
  Classes, SysUtils, u_data;

exports
  SomeFunc name 'SomeFunc';

begin
end.


unit u_data;

{$mode delphi}{$H+}

interface

uses
  Classes, SysUtils;
 
function SomeFunc(aValue: string): string; stdcall;

implementation

function SomeFunc(aValue: string): string; stdcall;
begin
  Result := aValue+aValue;
end;

end.



I use string type to verify that problem is not linked with strings.
{$H+} option is to control Heap, as I understand. heap.inc is a
functional analog of SharedMem in Delphi.

Part of program for test library.

Code: [Select]
function SomeFunc(aValue: string): string; stdcall; external
'lib_main.dll';


And it works good.

After this I add a package for work with FB database. So, library code
looks:

Code: [Select]
library lib_main;

{$mode delphi}{$H+}

uses
  Classes, SysUtils, u_data, fiblaz;

exports
  SomeFunc name 'SomeFunc';

begin
end.


When I test "new" library my program fails with message(translated
from russian): Error initializing application (0xC0000005). I tried to
add another units in uses section for tests. Sometime I get error
"Error initializing application (0xC0000142)"




Is it a bag of FPC or I do something incorrect?

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Phil · 2008-04-15 13:51

Quote from: "FreekNel"Is it a bag of FPC or I do something incorrect?

In general you don't pass dynamically allocated types to or from a
library.

You can pass these types: pchar, integer, etc.

That may not have anything to do with your problem.

Thanks.

-Phil

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Leledumbo · 2008-04-16 03:48

Quote{$H+} option is to control Heap, as I understand.
Just to guide you to the right way, {$H+} means 'string' type will be
an alias to 'ansistring' instead of the default 'shortstring' as long
as it isn't appended with square brackets ([]). Don't know why they
(fpc developers) use H, perhaps they're out of letter.

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Marc · 2008-04-16 09:17

H+ is delphi compatible

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FreekNel · 2008-04-16 17:26

Thanks to all, but it isn't solves my problem. I wrote same test
library in Delphi 7. It works. I can't understand, what is wrong in my
actions...One person advice me to look at initialize section in linked
unit. I find only standart procedure of registration package...

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FreekNel · 2008-04-17 02:43

Tried to write console application. Result is:
[FORMS.PP] ExceptionOccurred
  Sender=Exception
  Exception=Unknown Run-Time error : 202
  Stack trace:
  $100094B3
TApplication.HandleException Unknown Run-Time error : 202
  Stack trace:
  $100094B3

Can't find module in components which uses Forms

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Phil · 2008-04-17 03:08

Quote from: "FreekNel"Tried to write console application. Result is:
[FORMS.PP] ExceptionOccurred
  Sender=Exception
  Exception=Unknown Run-Time error : 202
  Stack trace:
  $100094B3
TApplication.HandleException Unknown Run-Time error : 202
  Stack trace:
  $100094B3

Can't find module in components which uses Forms

In general you don't use Forms in console apps or libraries (DLL's).

Thanks.

-Phil

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FreekNel · 2008-04-17 03:21

Quote
In general you don't use Forms in console apps or libraries (DLL's).


Yes, but fiblaz uses Forms. Variables such as Application, Screen and
so on. As for me, I need FIBDataBase and FIBQuery units only. Tests
fail  After excluding Forms unit, I have another ErrorCode -
0xC0000142. Probably, it's nessesary to use Delphi to write my
library...