c++ - What is the meaning of the code? -


i have read define function c define, , can not understand usage of [&]() -> long int.is assign type of return of function. can expalain me in detail? thanks

    # define temp_failure_retry(expression)                 \         [&]() -> long int                               \         {                                               \             long int __result;                          \                 __result = (long int)(expression);      \                while (__result == -1l && errno == eintr);  \             return __result;                            \         }()

it lambda expression of form:
[ captures ] ( params ) -> ret { body }

  • [&] captures automatic variables used in body of lambda reference , current object reference if exists
  • there no parameter
  • return type long int
  • {} contains definition of lambda

for details refer cpp reference link


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