Re: Inconsistency between results of pretty-printing children

[Oliver Buchtala <oliver.buchtala@googlemail.com>]

On 20.07.2012 22:13, Tom Tromey wrote:
>>>>>> "Oliver" == Oliver Buchtala <oliver.buchtala@googlemail.com> writes:
> Oliver> here the doc:
> Oliver> http://sourceware.org/gdb/onlinedocs/gdb/Pretty-Printing-API.html
> Oliver> under display_hint "map"
>
> Ok, I see.
>
> In the 'map' case, each item returned by the 'children' iterator must
> still be a 2-tuple of the form (NAME VALUE).
>
> What 'map' means is that the first item fetched from the iterator is
> considered to be a key in the map, and the second item fetched from the
> iterator is considered to be the corresponding value.  Then the 3rd item
> is a key again, the 4th is a value again, and so on.
>
> In the CLI the NAME parts are omitted when printing, in this case, just
> because it makes the output prettier.
>
> In MI, nothing changes -- the hint is emitted and the MI client is
> expected to take whatever action it thinks appropriate.
>
>
> Here's an abbreviated example from the libstdc++ test suite:
>
>    std::map<std::string, int> mp;
>    mp["zardoz"] = 23;
> // { dg-final { note-test mp {std::map with 1 elements = {["zardoz"] = 23}} } }
>
> That last line means that 'print mp' here should show:
>
>      std::map with 1 elements = {["zardoz"] = 23}
>
> If you dig into the libstdc++ StdMapPrinter code you see:
>
>          def next(self):
>              if self.count % 2 == 0:
>                  n = self.rbiter.next()
>                  n = n.cast(self.type).dereference()['_M_value_field']
>                  self.pair = n
>                  item = n['first']
>              else:
>                  item = self.pair['second']
>              result = ('[%d]' % self.count, item)
>              self.count = self.count + 1
>              return result
>
> So in the example above it returns a list like
>
>      [ ('[0]', '"zardoz"'), ('[1]', 23) ]
>
>
>
> My question for you is: how can we improve the documentation to make
> this more clear?
>
> Right now they read:
>
> @item map
> Indicate that the object being printed is ``map-like'', and that the
> children of this value can be assumed to alternate between keys and
> values.
>
>
> Tom
Back again...

I tried this approach.
This does not look pretty in MI debuggers... (e.g. nemiver)

Instead of providing
[("a", 1), ("b", 2)]
I tried
[("[0], "a"), ("[1]", 1), ("[2]", "b"), ("[3]", 2)]

This looks pretty with gdb print... though not pretty with any of my IDEs.

So, I am sorry... problem remains.

Regards,
Oliver