From: Brian Candler <B.Candler@...>
Date: 2003-07-16T00:54:26+09:00
Subject: Re: Determining if a String is marshalled

On Wed, Jul 16, 2003 at 12:45:46AM +0900, Daniel Berger wrote:
> I was just wondering if there's a way to determine if a string has been 
> marshalled without visual inspection.  Something along the lines of 
> "string.marshalled?"  or "string.kind_of?(MarshaledString)".  Is there a 
> regex I could use?

Check for the first two bytes, which are the major/minor version number.
Rather than hard-code it, you could do

   marshall_sig = Marshal.dump("")[0..1]
   marshall_check = /\A#{marshall_sig}/

irb(main):004:0> "abc" =~ marshall_check
=> nil
irb(main):005:0> Marshal.dump(123) =~ marshall_check
=> 0

Of course, the string might actually start with those bytes, but they are
low ("\004\006" on my machine) so unlikely to occur in a normal string.

Regards,

Brian.