I've had my first go at writing a DLL in Delphi. So far so good. By using a typelib I've been able to pass Widestrings to and from the DLL without difficulty.
What's curious at the moment is that I'm using VB6 as the testbed, and every time I run a test within the IDE, the program runs and then the IDE process suddenly disappears from memory - no error messages, nothing. If I step through the code, everything works fine until I execute the last line, then the IDE disappears.
By contrast, when I compile the test to an EXE the program runs to its end, without error messages etc.
Has anyone had this problem before and is there an obvious solution that's staring me in the face?
Source code below, in case it matters:
-- project
library BOSLAD;
uses
ShareMem,
SysUtils,
Classes,
BOSLADCode in 'BOSLADCode.pas';
exports
version,
DMesg,
foo;
{$R *.res}
begin
end.
-- unit
unit BOSLADCode;
interface
function version() : Double; stdcall;
procedure DMesg(sText : WideString; sHead : WideString ); stdcall;
function foo() : PWideString; stdcall;
implementation
uses Windows;
function version() : Double;
var
s : String;
begin
result := 0.001;
end;
procedure DMesg( sText : WideString; sHead : WideString);
begin
Windows.MessageBoxW(0, PWideChar(sText), PWideChar(sHead), 0);
end;
function foo() : PWideString;
var s : WideString;
begin
s := 'My dog''s got fleas';
result := PWideString(s);
end;
end.
-- typelib
// This is the type library for BOSLAD.dll
[
// Use GUIDGEN.EXE to create the UUID that uniquely identifies
// this library on the user's system. NOTE: This must be done!!
uuid(0C55D7DA-0840-40c0-B77C-DC72BE9D109E),
// This helpstring defines how the library will appear in the
// References dialog of VB.
helpstring("BOSLAD TypeLib"),
// Assume standard English locale.
lcid(0x0409),
// Assign a version number to keep track of changes.
version(1.0)
]
library BOSLAD
{
// Now define the module that will "declare" your C functions.
[
helpstring("Functions in BOSLAD.DLL"),
version(1.0),
// Give the name of your DLL here.
dllname("BOSLAD.dll")
]
module BOSLADFunctions
{
[helpstring("version"), entry("version")] void __stdcall version( [out,retval] double* res );
[helpstring("DMesg"), entry("DMesg")] void __stdcall DMesg( [in] BSTR msg, [in] BSTR head );
[helpstring("foo"), entry("foo")] void __stdcall foo( [out,retval] BSTR* msg );
} // End of Module
}; // End of Library