Re: [gentoo-portage-dev] Composite exceptions?

[Brian Harring]

On Sat, Feb 27, 2010 at 05:02:18AM +0100, Sebastian Pipping wrote:
> On 02/27/10 04:20, Zac Medico wrote:
> > Do you have an example case where you want to use this?
>
> Multiple defects in metadata.xml are such a case.
> At some point all the exceptions will have to collected, e.g. two
> invalid herds are mentioned.  In that case a single exception with a
> list of invalid herds may suffice but it gets worse when combining
> errors of slightly different types.

I'd suggest looking at pchecks design instead of trying to do 
composite exceptions- essentially pass in a reporter that is invoked 
w/ the failure/'exception' instead passed in.

Doing what you're suggesting (catching all exceptions at the top and 
trying sum them essentially) results in screwy code flow in the 
specific check- consider a check that can flag multiple issues.  
Chucking an exception means you get the first warning spotted (and 
just that).

Do the reporter/observer/tweaked visitor approach, you get all of the 
issues, and it's left to the reporter to decide what to output (and 
how to format it).

Also makes it a helluva lot easier to serialize the results into 
pickles, or go parallel (multiple processes running, the reporter 
in the subprocess just serializes the issue to a central process that 
then amalgamates the results).

~harring