From: "Berger, Daniel" <Daniel.Berger@...>
Date: 2006-02-03T00:29:34+09:00
Subject: Re: memoize to a file

> -----Original Message-----
> From: Mauricio Julio Fern�ndez Pradier 
> [mailto:ferferse@telefonica.net] On Behalf Of Mauricio Fernandez
> Sent: Wednesday, February 01, 2006 4:48 PM
> To: ruby-talk ML
> Subject: Re: memoize to a file
> 
> 
> On Thu, Feb 02, 2006 at 06:49:49AM +0900, Daniel Berger wrote:
> > > and it instead of silently failing I now see the error 
> message: "in 
> > > `load': marshal data too short (ArgumentError)"
> > >
> > > My questions:
> > > 1  What is causing this error? (possibly Windows related?)
> > 
> > That is odd.  I've run it on Windows with no trouble in the past.
> 
> (FTR: file not opened in binary mode, [177651])
> > Is it possible you ran this program using 1.8.2, downloaded 1.8.4, 
> > then re-ran the same code using the same cache?  It would fail with 
> > that error if such is the case, since Marshal is not compatible 
> > between versions of Ruby - not even minor versions.
> 
> The Marshal format hasn't changed for a while:
> 
> batsman@tux-chan:~/Anime$ ruby182 -v -e 'p 
> [Marshal::MAJOR_VERSION, Marshal::MINOR_VERSION]' ruby 1.8.2 
> (2004-12-25) [i686-linux] [4, 8] batsman@tux-chan:~/Anime$ 
> ruby -v -e 'p [Marshal::MAJOR_VERSION, 
> Marshal::MINOR_VERSION]' ruby 1.8.4 (2005-12-24) [i686-linux] [4, 8]
> 
> Also note that ruby can read Marshal data in older formats if 
> the MAJOR_VERSION hasn't changed (i.e. if only the 
> MINOR_VERSION was increased):
> 
> 
>     if (major != MARSHAL_MAJOR || minor > MARSHAL_MINOR) {
> 	rb_raise(rb_eTypeError, "incompatible marshal file 
> format (can't be read)\n\ \tformat version %d.%d required; 
> %d.%d given",
> 		 MARSHAL_MAJOR, MARSHAL_MINOR, major, minor);
>     }
>     if (RTEST(ruby_verbose) && minor != MARSHAL_MINOR) {
> 	rb_warn("incompatible marshal file format (can be 
> read)\n\ \tformat version %d.%d required; %d.%d given",
> 		MARSHAL_MAJOR, MARSHAL_MINOR, major, minor);
>     }
> 
> 
> (after some searching...)
> 
> Back in Apr. 2001, matz said that "Marshal should not change 
> too much (unless in upper compatible way)" [14063]. The last 
> minor change happened after 1.6.8 (6 -> 8), and MARSHAL_MAJOR 
> was already 4 in v1_0_1, 7 years, 2 months ago (at which 
> point I got tired of CVSweb).
> 
> Marshal's format is more stable than we think.

I guess I'm once bitten, twice shy as a result of the transition from 1.6.8 to 1.8.0 not too long ago.  Thanks for the correction.

Dan