[Development] Semi-private headers in Qt

[Elvis Stansvik]

Den tors 21 maj 2026 13:46Artem Dyomin via Development <
development at qt-project.org> skrev:

>
>    -  c++ keywords (volatile, mutable), they might suggest that the
>    folder has something to do with c++ mutables, volatiles, etc.
>    - include <QtGui/6.12/qrhi.h> requires updates all usages in Qt code
>    before each release, not sure that we want to handle this dogfood.
>    - spi makes sense for me.
>
>
How about underscore, like used in Python sometimes to indicate private-ish
:)

<QtGui/_/blabla.h>

*hides*


>    -
>
>
>
> Confidential
> ------------------------------
> *From:* Tor Arne Vestbø <Tor.arne.Vestbo at qt.io>
> *Sent:* Thursday, May 21, 2026 1:41 PM
> *To:* Volker Hilsheimer <volker.hilsheimer at qt.io>
> *Cc:* Edward Welbourne <edward.welbourne at qt.io>;
> development at qt-project.org <development at qt-project.org>; Artem Dyomin <
> artem.dyomin at qt.io>
> *Subject:* Re: [Development] Semi-private headers in Qt
>
>
> On 21 May 2026, at 13:30, Volker Hilsheimer via Development <
> development at qt-project.org> wrote:
>
> One idea I just had was to use the major.minor version number of Qt.
>
> #include <QtGui/6.12/qrhi.h>
>
> The advantage is that you are clearly seeing that you are using an API
> that is specific to that Qt version.
> The disadvantage is that you have to change the include statement when
> upgrading Qt version, but that might as much be an advantage because it
> creates awareness - just because things still compile doesn't necessary
> mean that they also still work the same way. And it can be made very simple
> by having a single wrapper-header for a project.
>
> Failing that my preference would be either
>
> unstable, unsupported, or semiprivate
>
>
> I suggest we squash all these uses-cases into an opaque `spi` suffix,
> which can covers both semi-private (experimental), and service-provider
> (system integration) interfaces. It’s also short to write :)
>
> #include <QtGui/spi/qplatformwindow.h> // Technically both semi-private
> and service-provider interface
>
> #include <QtMultimedia/spi/qgstreamvervideosource.h> // Semi private API
>
> Tor Arne
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