From: Robert Klemme <shortcutter@...>
Date: 2008-09-23T03:41:48+09:00
Subject: Re: at_exit handler *except* for fatal runtime error

On 22.09.2008 17:56, DMisener wrote:
> On Sep 19, 6:57 am, Robert Dober <robert.do...@gmail.com> wrote:
>> On Thu, Sep 18, 2008 at 10:07 PM, Robert Klemme> Oh, come on.  
>> You can easily use that information to build what you want.
> 
> Actually inverting the logic isn't that easy (at least for me)
> 
>> Hmm maybe not Robert, my feeling is that they should not do what they
>> are doing in the at_exit block.
> 
> I'm certainly not married to the the at_exit approach.
> 
>> OP can you give us the rationale behind this design. At first sight I
>> believe you should do what you want in the main script. Look at Ara's ideas e.g.
> 
> Simple problem:
> 
> Create a tentative output working file.  If the program exits
> "cleanly" then rename the work file
> to its "final" name.  If not leave the work file for possible
> examination.
> 
> Ideally this File.open_tentative_output_file would be plug
> "compatible" with the simple File.open
> (i.e. support modes and blocks).
> 
> Perhaps I'm trying to make life "too easy" for the application
> programmer by eliminating the need for
> an explicit File.close_all_pending_tentative_file routine.

It rather seems that you're making *your* life too hard. :-)

>  That is
> really all that I am trying to achieve with the
> at_exit{} code.  One less step to remember.  But perhaps the
> implementation complexity isn't worth it.

Why do you need at_exit for this - especially if you want to be 
compatible to File.open?

def File.open_tentative_output_file(tmp, final, mode = "w", &b)
   raise "Need a block" unless b
   File.open(tmp, mode, &b)
   File.rename tmp, final
end

Done.

Cheers

	robert