Awesome description, Jacob! It’s been some time since I’ve had to be thinking at these lower levels, so I just need some oil on my mind. I really appreciate the details from you and Jeff. You both have saved me much time and confusion.
Regards
From: jacob <jacobgilbert@protonmail.com>
Sent: Thursday, June 30, 2022 9:43 AM
To: Jeff S <e070832@hotmail.com>
Cc: Jeff Long <willcode4@gmail.com>; discuss-gnuradio@gnu.org
Subject: RE: Is PMT_NIL a Valid Dictionary?
Just to help clarify this a bit, PMT_NIL
is a valid PMT object (not to be confused with null)
PMT Dictionary type objects are nested pairs, and empty dictionary type objects (from
pmt::make_dict() for example) are literally represented as a single PMT_NIL object under the hood, so this is specifically checked for and
passes is_dict(). As dictionary items are added, the base dictionary (or empty dict / PMT_NIL object) gets paired with added key-value
pairs. Its not the best possible implementation, but has served GR for some time. PMTs are getting a modernization / overhaul soon.
The is_pdu() check should abstract that oddness a bit.
------- Original Message -------
On Thursday, June 30th, 2022 at 7:12 AM, Jeff S <e070832@hotmail.com> wrote:
Cool. I appreciate the clarification. I had always taken an empty dictionary as a dictionary object without data, and a NIL as not an object, and the two were different. This
helps my PDU checking.
And I also found the update I missed which added is_pdu(), which simplifies some of my checking. So, even better!
Thanks for the help,
Jeff
Yes, an empty dict is NIL, so that is (confusingly) valid.
GNU Radio Version: v3.9.6.0-23-ge3506b13
I was writing a QA test and decided to try,
self.assertTrue(pmt.is_dict(pmt.PMT_NIL))
and it passes. I was just wondering if pmt.PMT_NIL is considered a valid dictionary object, as opposed to,
my_dict = pmt.make_dict()
self.assertTrue(pmt.is_dict(my_dict))
Just trying to get a better understanding and couldn’t find an answer.
Regards,
Jeff
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