Title: How to delete our own application: the professional way
Question: How to uninstall an application leaving the system completly clean? After 4 betas, there's the way to do things professional.
Answer:
After reading Misha's article on how to remove the application file (http://www.delphi3000.com/articles/article_514.asp), i wrote down my solutions (http://www.delphi3000.com/articles/article_2256.asp), but I called them as "betas" since every one of them had PRO and VS.
The final solutions is now available.
Taking from Beta 2, we can create a different program to put into the temp folder. After executing the deletion of the main-application file it will sign up for self delection at reboot with a simple MoveFileEx API call.
Specifing the MOVEFILE_DELAY_UNTIL_REBOOT flag into the dwFlags parameter, the MoveFileEx will plan the operation to be runned at next reboot.
Actually, MoveFileEx is used to rename or move a file, but you can also use NIL as the destination parameter and that will mean "delete the file".
Example:
MoveFileEx('C:\temp\FileToRemove.dat', nil, MOVEFILE_REPLACE_EXISTING or MOVEFILE_DELAY_UNTIL_REBOOT);
I also bettered it to not loop more that 5 seconds. You can change this changing the MAX_RUN_TIME constant value (in milliseconds).
The DelFile source code will then be as follow:
program DelFile;
{$APPTYPE CONSOLE}
uses
SysUtils, Windows;
const
MAX_RUN_TIME=5000;
var
StartTime: dword;
begin
if ParamCount=0 then Exit; // no file specified for deletion
StartTime:=GetTickCount();
repeat
sleep(10);
until DeleteFile(PChar(ParamStr(1))) or (GetTickCount()-StartTimeMAX_RUN_TIME);
MoveFileEx(PChar(ParamStr(0)), nil, MOVEFILE_REPLACE_EXISTING or MOVEFILE_DELAY_UNTIL_REBOOT);
end.
That's is, but unfortunately it seems to work only in NT-based systems.