[Ovmsdev] Duktape Persistent Function References

[Michael Balzer]

Mark,

the issue is, there are ambiguous overloads of these methods in their
classes, and the compiler doesn't know which one to pick.

-
https://stackoverflow.com/questions/10111042/wrap-overloaded-function-via-stdfunction
-
https://stackoverflow.com/questions/30393285/stdfunction-fails-to-distinguish-overloaded-functions

I prefer to keep my command stub names distinguished from their
implementation counterparts, but apparently that doesn't apply to all of
us ;-)

Coming C++ versions may be smart enough to deduce the method to pick
from the expected signature.

For now, the compiler needs a hint here. I've added two preprocessor
macros to make these hints readable.

Regards,
Michael


Am 25.09.20 um 08:07 schrieb Mark Webb-Johnson:
> @Michael,
>
> I’ve tried merging this (along with all the other recent changes in
> master) into the for-v3.3 branch, but am now getting compilation
> errors. The two files with issues are:
>
>     components/retools_testerpresent/src/retools_testerpresent.cpp
>     components/vehicle_mgev/src/vehicle_mgev.cpp
>
>
> Both in the RegisterCommand function call with the static class member
> function as a parameter. Not sure if that new way is used elsewhere?
>
> Example compiler output is:
>
>     CXX build/retools_testerpresent/src/retools_testerpresent.o
>     .../components/retools_testerpresent/src/retools_testerpresent.cpp:
>     In constructor
>     'OvmsReToolsTesterPresentInit::OvmsReToolsTesterPresentInit()':
>     .../components/retools_testerpresent/src/retools_testerpresent.cpp:140:5:
>     error: no matching function for call to
>     'OvmsCommand::RegisterCommand(const char [6], const char [48],
>     <unresolved overloaded function type>, const char [23], int, int)'
>          );
>          ^
>
>     CXX build/vehicle_mgev/src/vehicle_mgev.o
>     .../components/vehicle_mgev/src/vehicle_mgev.cpp: In constructor
>     'OvmsVehicleMgEv::OvmsVehicleMgEv()':
>     .../components/vehicle_mgev/src/vehicle_mgev.cpp:143:5: error: no
>     matching function for call to
>     'OvmsCommandApp::RegisterCommand(const char [8], const char [15],
>     <unresolved overloaded function type>)'
>          );
>          ^mand(const char* name, const char* title,
>                       ^
>
>
> I tried for a while, but can’t see what is wrong. Perhaps some missing
> header file? Anyway, I’ve committed the merge of master into for-v3.3
> (even though it doesn’t compile) and just commented out those
> registrations in my local copy.
>
> Can you help?
>
> Thanks, Mark.
>
>> On 12 Sep 2020, at 5:12 AM, Michael Balzer <dexter at expeedo.de
>> <mailto:dexter at expeedo.de>> wrote:
>>
>> Mark,
>>
>> Am 11.09.20 um 18:11 schrieb Michael Balzer:
>>>> I agree it is not necessary; my suggestion is purely to clean it up
>>>> and enhance functionality. The problem at the moment is that
>>>> OvmsCommand execute callbacks can only be to function callbacks (not
>>>> objects). It doesn’t even use the c++ bind function callback
>>>> mechanism (like notification, etc, for example). It is what it is,
>>>> and changing now is very hard.
>>>
>>> That slipped my attention, but upgrading OvmsCommand to accept any
>>> function type should be simply changing m_execute and m_validate to
>>> std::function, or do I miss something?
>>
>> Just did this locally, works perfectly. Shall I push the change or have
>> you begun working on ovms_command?
>>
>> If so, it's really just exchanging the function signatures for these
>> types:
>>
>> typedef std::function<void(int, OvmsWriter*, OvmsCommand*, int, const
>> char* const*)> OvmsCommandExecuteCallback_t;
>> typedef std::function<int(OvmsWriter*, OvmsCommand*, int, const char*
>> const*, bool)> OvmsCommandValidateCallback_t;
>>
>> Patch attached.
>>
>> Regards,
>> Michael
>>
>> -- 
>> Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
>> Fon 02333 / 833 5735 * Handy 0176 / 206 989 26
>>
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>
>
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-- 
Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
Fon 02333 / 833 5735 * Handy 0176 / 206 989 26

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