Re: [PATCH] Debug Methods in GDB Python

[Siva Chandra <sivachandra at google dot com>]

On Mon, Dec 16, 2013 at 9:56 AM, Doug Evans <xdje42@gmail.com> wrote:
> Note that the grouping in the pretty-printer API is because one
> pretty-printer can pretty-print several objects, and the functionality
> is split into two steps: the lookup object returns a separate object
> which is then later used to do the printing, and the lookup can record
> in the returned pretty-printer-worker object whatever state it wants.
> In dm-v6 AFAICT lookup and functionality exist in the same object so
> that's not possible (e.g., the DebugMethod.match method returns
> True/False instead of, e.g., a debug-method-worker object).
>
> We could, I think(!), go with debug-methods as in v6, sans method
> groups, and later extend it if a more formal grouping is needed.
> I wonder, though, about the match method returning True/False vs the
> pretty-printer way of the lookup object returning an object that then
> does the printing.
> [In the debug method case the lookup method might want to return a
> list if the method is overloaded.]
> Unless there's a compelling reason to be different, I like
> "Consistency Is Good", so that's what I'm shooting for.
> [But if there is a compelling reason to be different, I'm not opposed
> to being different here.]

I do not have a compelling reason to be different here. I only have
couple of personal reasons for doing it that way:

1. <locus>.pretty_printers is actually not a list of pretty printers,
but a list of functions which return a pretty printer. I wanted
<locus>.debug_methods to be a list of actual debug methods.
2. Debug methods are queried for a match twice; Once for object type
and name match, next for argument type match. I wanted these to be
together instead of in separate places (as in, an object-method
matching function and a stateful worker object which does arg type
matching). But I agree that this makes the debug methods stateless
(almost! They do have a name and enabled flag.) for most cases.

I can modify and send a new patch if you feel debug methods should
parallel pretty printers here.

Thanks,
Siva Chandra