To static or not to static?

[JonB]

@TomZ
Two votes out of two responses for not doing static on a (private) method which does not access this. Shame for not being as "tidy" as I like it in C#, but if that's the C++ convention I will change over to it (obviously marking them as const instead)....

Will await any further opinions and mark this as "Solved" later.

[J.Hilk]

@JonB const, noexcept and [[nodiscard]] where ever possible ! :D

[JonB]

@J-Hilk If you think I'm adding that sort of stuff to all my functions I'm not going to! :) I don't think even Qt headers do the "noexcept and [[nodiscard]] " mostly.

[J.Hilk]

@JonB this actually would be good practice :P

[JonB]

@J-Hilk It would, but it's too much typing every time to change the defaults. If I wanted that I'd consider changing to Rust ;-)

[J.Hilk]

@JonB to bad that people refuse to change the standard or at least to add a flag to the compiler to change the default interpretations.

Immagine people having to write [[maybe_unused]] or mutable, the horror!

[mranger90]

For what its worth, the coding guidelines for my company say that such methods should be external to the class. We tend to bundle them up in common libraries and wrap them in their own namespace.

[JonB]

@mranger90
FWIW, personally I find that an extraordinarily burdensome guideline. Small utility methods which happen not to use this but are useful privately in a class (and perhaps meaningless elsewhere) are not at all uncommon. (I haven't done so, but I would be surprised if I don't find such in, say, Qt sources.) Having to move them out does not seem nice to me. But what do I know, I respect you say that is what your company requires.

EDIT
I don't have downloaded Qt sources. Just using woboq for Qt5 and having a look at, say, QString for private static methods I happenstanced on, say, declaration https://codebrowser.dev/qt5/qtbase/src/corelib/text/qstring.h.html#_ZN7QString14compare_helperEPK5QChariS2_iN2Qt15CaseSensitivityE

private:
    static int compare_helper(const QChar *data1, int length1,
                              const QChar *data2, int length2,
                              Qt::CaseSensitivity cs = Qt::CaseSensitive) noexcept;

definition https://codebrowser.dev/qt5/qtbase/src/corelib/text/qstring.cpp.html#_ZN7QString14compare_helperEPK5QChariS2_iN2Qt15CaseSensitivityE

/*!
    \internal
    \since 4.5
*/
int QString::compare_helper(const QChar *data1, int length1, const QChar *data2, int length2,
                            Qt::CaseSensitivity cs) noexcept
{
    Q_ASSERT(length1 >= 0);
    Q_ASSERT(length2 >= 0);
    Q_ASSERT(data1 || length1 == 0);
    Q_ASSERT(data2 || length2 == 0);
    return qt_compare_strings(QStringView(data1, length1), QStringView(data2, length2), cs);
}

A perfect example of a private utility method that they seem to declare static as I would have done (though I have not checked whether it might be called from some static method).

[JoeCFD]

@JonB said in To static or not to static?:

compare_helper

qt_compare_strings is static as well. That may be the reason why compare_helper is static. It does have to be, I guess. If not, the return is different.
return QString::qt_compare_strings(QStringView(data1, length1), QStringView(data2, length2), cs);

If the static function performs operations that are related to the class as a whole, rather than specific instances, it may make sense to keep it static and private.

I do not know if it is a good practice or not. all math funcs for exampes std::cos are defined in namingspace std. The reason could be that template for class member funcs were introduced in C++ 14. In or before C++ 11, it was not possible to use template for member funcs in a class.

[JonB]

@JoeCFD said in To static or not to static?:

qt_compare_strings is static as well. That may be the reason why compare_helper is static

Sorry, that does not make sense. You can of course call a static function from a non-static member function, just not the other way round. This would not be any reason to choose to make the calling method, QString::compare_helper(), be static.

it may make sense to keep it static and private

But you can see the other responders here are suggesting I do not make private methods static, which I am now following.

[JoeCFD]

@JonB I guess both ways work. I do not have preference.