[zeromq-dev] [zproject] How to detect fresh = "1" attribute?

Pieter Hintjens ph at imatix.com
Mon Jan 4 12:48:00 CET 2016

You can guess the fresh attribute by looking for a const modifier. In
principle all strings that are not const are fresh. We could specify
this as a rule, even. It does not apply to other structures though. As
Joe points out, the model is always going to be more accurate than the

On Mon, Jan 4, 2016 at 7:23 AM, Joe McIlvain <joe.eli.mac at gmail.com> wrote:
> This is one example that I think demonstrates that we actually do encode
> more information in the zproject API models than is found in the C headers.
> This extra information is necessary for the API to understood to generate
> well-behaved bindings, but is, as you've found, merely an understood
> convention in C.
> It was this kind of property that made me first skeptical of your mkapi.py
> project.  In general, I think it would be best to view it as a best effort
> to translate C header to API model, useful so that the initial models for a
> project moving to using zproject API models does not have to write the bulk
> of the XML by hand.  However, after this point it's probably best to tweak
> and continue maintenance using the established zproject workflow, modifying
> the API model first when you modify your API, allowing the C header to be
> generated.
> In general, I think the API models will always encode a bit more information
> than you can (reliably) extract from the C header, and this is by design
> (speaking as the one who designed most of the initial structure of the
> models).  The API models were introduced for that specific reason - if the C
> headers could reliably provide all of the information needed to generate
> proper high-level bindings, then we wouldn't need the API models at all.  As
> it turns out, the API models are a clean way to make explicit and
> machine-readable the properties that were previously only encoded in highly
> varied human-language comments.
> On Sun, Jan 3, 2016 at 12:04 PM, Michal Vyskocil <michal.vyskocil at gmail.com>
> wrote:
>> Hi,
>> during the last few weeks I have improved the mkapi.py enough the
>> generated model is almost 1:1 with the one from czmq (I am testing
>> zactor.xml right now).
>> My biggest problem is how can I detect fresh = "1" attribute. Right
>> now code adds fresh="1" to each function, which returns non const
>> pointer. Which is far from true, as czmq usually have functions
>> returing the low-level objects The question is how to deal with it?
>> I see only solution:
>> Detect phrase "caller is responsible for ..." or so in functions
>> comment and add fresh="1" only for those functions.
>> It is a bit hacky, but at least encourage developers to explicitly
>> document ownership.
>> What do you think?
>> --
>> best regards
>>      Michal Vyskocil
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