php// --------------------// foo() will never get called as those operators are short-circuit$a = (false
提供非布尔值将引发异常: iex>1andtrue**(BadBooleanError)expectedabooleanonleft-sideof"and",got:1 or和and是短路short-circuit
theclientwouldthenhavetomakeasecondrequesttoobtaintheentirecurrentrepresentation.The"If-Range"headerfieldallowsaclientto"short-circuit"thesecondrequest.Informally
theclientwouldthenhavetomakeasecondrequesttoobtaintheentirecurrententity-body.TheIf-Rangeheaderallowsaclientto"short-circuit"thesecondrequest.Informally