From: Tom Tromey <tromey@redhat.com>
To: Vladimir <volo.zyko@gmail.com>
Cc: archer@sourceware.org
Subject: Re: pretty printing of smart pointers and making function calls
Date: Wed, 22 Feb 2012 21:38:00 -0000 [thread overview]
Message-ID: <87obsqo8fb.fsf@fleche.redhat.com> (raw)
In-Reply-To: <loom.20120208T150635-160@post.gmane.org> (Vladimir's message of "Wed, 8 Feb 2012 16:35:39 +0000 (UTC)")
>>>>> "Vladimir" == Vladimir <volo.zyko@gmail.com> writes:
Sorry about the long delay here.
I managed to forget about this thread somehow :(
Tom> You can work around this a little by having the base printer also print
Tom> the pointed-to value. This is what the libstdc++ iterator printers do
Tom> (for now).
Vladimir> I'm not sure I understand you correctly. Do you mean that if
Vladimir> the user asks for a value of variable a and pretty printer
Vladimir> knows that it's a pointer then along with pointer address it
Vladimir> should print the value the pointer points too? Anyway some
Vladimir> reference to document or example would be useful here.
E.g., the libstdc++ printers for iterators print the referred-to object
as well. Here's a simple one:
class StdSlistIteratorPrinter:
"Print __gnu_cxx::slist::iterator"
def __init__(self, typename, val):
self.val = val
def to_string(self):
nodetype = find_type(self.val.type, '_Node')
nodetype = nodetype.strip_typedefs().pointer()
return self.val['_M_node'].cast(nodetype).dereference()['_M_data']
This looks into the iterator representation, finds the pointer to the
iterated-over data, and prints that.
This is a hack, but often a useful one.
Vladimir> But you are right that this doesn't work with core-file. Is
Vladimir> there any way to check in Python whether I debug alive process
Vladimir> or see its dead body?
Nothing direct but as a workaround you can often find this stuff using
gdb.execute(..., to_string=True) and then parsing the result.
The output here might change between releases, though, so it is
generally better to get a real Python API.
Tom
prev parent reply other threads:[~2012-02-22 21:38 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-25 13:20 Vladimir
2012-01-31 18:26 ` Tom Tromey
2012-02-08 16:36 ` Vladimir
2012-02-22 21:38 ` Tom Tromey [this message]
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