From: Michael Libby <michael.c.libby@...>
Date: 2008-08-22T00:54:05+09:00
Subject: Re: possible simple marshall error

On Thu, Aug 21, 2008 at 10:50 AM, Michael Libby
<michael.c.libby@gmail.com> wrote:
> On Thu, Aug 21, 2008 at 10:34 AM, Lex Williams <etaern@yahoo.com> wrote:
>> I recently tried to learn to use Marshal with a simple script , but I
>> keep getting the following exception : x.rb:6:in `load': marshal data
>> too short (ArgumentError)
>>
>> This is the script :
>>
>> hsh = {:first => [1,2,3],:second => [4,5,6] }
>>
>> File.open("saved.m","w").puts(Marshal.dump(hsh))
>
> This line is actually the problem from what I can tell.
>
> Try instead:
>
> File.open("saved.m", "w"){|f| f.puts(Marshal.dump(hsh)) }

And allow me to point out why what you have "should" work (and might
in some cases), but doesn't: buffering.

The way you had it, you open a file, and write to it, but never close
the file before trying to read the file. So what you wrote to the file
is still in the file buffer rather than written to disk. At least this
is how it worked on my system (WindowsXP). I believe this problem
would be the same on Linux.

Using File::open with a block automatically closes the filehandle at
the end of the block, flushing the buffer and giving the later
File::read something to actually read.

 -Michael