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c++qtno-op

What's the purpose of `qt_noop`

I just found the existence of qt_noop() define in the qglobal.h as:

inline void qt_noop() {}

What's the point of it?

Solution

  • The "noop" name is short for "no operation", meaning it is a place-holder function that does nothing.

    You may also know NOP, which exists in assembly-language.

    I know it's used internally in some macros that should do something only for debug builds, for example:

    #  ifndef QT_NO_DEBUG
#    define Q_ASSERT(cond) ((!(cond)) ? qt_assert(#cond,__FILE__,__LINE__) : qt_noop())
#  else
#    define Q_ASSERT(cond) qt_noop()
#  endif
#endif