I ran into this problem in the past when trying to allow a function to accept filenames or filehandles.

From my testing at the time I don't think it is possible to determine if a scalar is a filehandle or not. As you point out the IO:: objects would be difficult to handle.

The solution that I can up with was just to assume that any references passed to the function were filehandles and any scalars were filenames. Here is an extract from the code.

    # If the filename is a reference it is assumed that it is a valid
    # filehandle, if not we create a filehandle.
    #
    if (ref($OLEfile)) {
        $fh = $OLEfile;
    }
    else {
        # Create a new file, open for writing
        $fh = FileHandle->new("> $OLEfile");
        if (not defined $fh) {
            croak "Can't open $OLEfile. ......";
        }

        # binmode file whether platform requires it or not
        binmode($fh);

    }

    # Store the filehandle
    $self->{_filehandle} = $fh;
[download]

This isn't bullet-proof but if the documentation is explicit then it may be sufficient.

--
John.

---

---

• Are you posting in the right place? Check out Where do I post X? to know for sure.
• Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:

  <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>

• Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
• Want more info? How to link or How to display code and escape characters are good places to start.