How to gain exclusive use of a file?

[qwert]

I need to open a file for exclusive use. IOW, have my script's open operation fail if any other application has the file open for editing or appending. In the help file, I located a statement that I've never used, but that sounded like the answer:

$file = _WinAPI_OpenFileDlg( * * * * * * *, BitOR($OFN_FILEMUSTEXIST, $OFN_SHAREAWARE))

But it never returns a non-zero error to indicate a problem, like when a text file is open in WordPad.

Can someone suggest a proper method? ... or point me to documentation?

Thanks in advance for help.