[Development] On deprecating functions

Christian Ehrlicher Ch.Ehrlicher at gmx.de
Mon Mar 4 19:46:00 CET 2019


Am 04.03.2019 um 19:28 schrieb Thiago Macieira:
> On Monday, 4 March 2019 09:58:40 PST Edward Welbourne wrote:
>> Christian Ehrlicher (4 March 2019 17:51) wrote
>>
>>> So what's the correct way to deprecate a function and not forgetting
>>> about QT_DEPRECATED later on as it happened with a lot of functions
>>> during Qt4 times?
>> Isn't that what
>> #if QT_DEPRECATED_SINCE(5, 13)
>> is for ?
> The point raised by hjk is that this causes warnings to anyone compiling code
> that needs to retain compatibility. There's no grace period. This is probably
> why we only documented the functions were deprecated with \obsolete, but never
> enabled warnings (except for Qt4-compat things). In that scheme, finding
> deprecated functions is done by raising QT_DEPRECATED_SINCE in your
> buildsystem and see what fails, instead of having warnings printed at you.
>
> Should we go back to this?
You know what happens in this case - nothing since noone notices... see 
all the usages of deprecated functions within QtBase which have been 
unrecognized for ages.
Lars mentioned a new macro Q_WARN_DEPRECATED_SINCE(major, minor) here: 
https://codereview.qt-project.org/#/c/254857/ - maybe this could help here?


Christian


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