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Code: Select all

library dlltest;

uses
  SysUtils,
  Classes,
  MyAccess;

procedure Test(MyConnection: TMyConnection); cdecl; export;
var q: TMyQuery;
begin
  try
    q:=TMyQuery.Create(nil);
    q.Connection:=MyConnection;
    q.SQL.Text:='select version() as ver';
    q.Open;    //  <--- Here is the error: Invalid class typecast
    q.Close;
  except
  end;
  FreeAndNil(q);
end;

exports
  Test;

begin
end.

Code: Select all

program dllcaller;

{$APPTYPE CONSOLE}

uses
 MyAccess;

procedure Test(MyConnection: TMyConnection); cdecl; external 'dlltest.dll' name 'Test';

var conn: TMyConnection;

begin
  try
    conn:=TMyConnection.Create(nil);
    conn.Server:='localhost';
    conn.Database:='mysql';
    conn.Port:=3306;
    conn.Username:='root';
    conn.Password:='root';
    conn.LoginPrompt:=False;
    conn.Open;
    Test(conn);
    conn.Close;
  except
  end;
end.

Code: Select all

library dlltest;

uses
  SysUtils,
  Classes,
  MyAccess;

procedure Test(MyConnection: TMyConnection); cdecl; export;
var
  con: TMyConnection;
  q: TMyQuery;
begin
  con := TMyConnection.Create(nil);
  q := TMyQuery.Create(nil);
  try
    con.AssignConnect(MyConnection);
    q.Connection := con;
    q.SQL.Text := 'select version() as ver';
    q.Open;
    q.Close;
  except
  end;
  FreeAndNil(q);
  FreeAndNil(con);
end;

exports
  Test;

begin
end.