9/1/2023 0 Comments Invoking java meaning![]() Input is "blue1" and this is due the virtual method invocation. The output could be "blue2" or maybe "red1". ( supersub.getColor() + supersub.number ) Super supersub = new Sub() //You can do this thanks Suppose you have a super class likeĪll right, so what is the out put of the next program? Don’t solve that error by coercing your intermediate result, instead, figure out what argument or local is not primitive.The virtual method invocation is a little tricky to explain. If you’ve got a loop (which you probably do if you need to optimize) make sure the loop locals are primitives first - then if you accidentally are producing a boxed intermediate result you’ll get an error on recur. Arithmetic on primitives yields primitives. So, the simplest route to fast math is to leave the operators alone and just make sure the source literals and locals are primitive. When the args are primitive locals, regular + and * etc do primitive math with an overflow check - fast and safe. Many people seem to presume only the unchecked- ops do primitive arithmetic - not so. If a hint doesn’t improve things in the end - take it out. The only exception is reflection warnings - you must get rid of them in any code that gets called frequently.Īlmost every time someone presents something they are trying to optimize with hints, the faster version has far fewer hints than the original. There’s usually no point in trying to optimize an outer loop, in fact it can hurt you as you’ll be representing things as primitives which just have to be re-boxed in order to become args to the inner call. Also, people reading your code don’t know if you are using unchecked for truncation or performance - best to reserve it for the former and comment if the latter. On a typical example, that has about a 5% difference in speed - well worth it. HotSpot does a good job at optimizing the overflow check, which will yield an exception instead of silent truncation. Do not use ^Integer etc.ĭon’t rush to unchecked math unless you want truncating operations. (let …) is the correct way to get a primitive local. Instead, use the let technique shown to place args in primitive locals if they need to participate in primitive arithmetic in the body. ![]() non-destructively) processing one or more arrays in order to produce a new array or aggregate value respectively.Īll arguments are passed to Clojure fns as objects, so there’s no point to putting arbitrary primitive type hints on fn args (excepting primitive array type hints, and long and double as noted). which produce int, long, etc.Ī set of "unchecked" operations for utmost performing, but potentially unsafe, integer (int/long) ops: unchecked-multiply unchecked-dec unchecked-inc unchecked-negate unchecked-add unchecked-subtract unchecked-remainder unchecked-divideĪ dynamic var to automatically swap safe operations with unchecked operations: *unchecked-math*Īmap and areduce macros for functionally (i.e. The num coercion function boxes primitives to force generic arithmeticĪrray cast functions ints longs, etc. produce primitives when consumer can take primitive ![]() Type hints for primitive arrays - ^ints, ^floats, etc.Ĭoercion ops int, float, etc. ![]() Recur forms that rebind primitive locals do so without boxing, and do type-checking for same primitive type.Īrithmetic (+,-,*,/,inc,dec,>= etc) is overloaded for primitive types where semantics are same.Īget / aset are overloaded for arrays of primitivesĪclone, alength functions for arrays of primitivesĬonstructor functions for primitive arrays: float-array, int-array, etc. Let/ loop-bound locals can be of primitive types, having the inferred, possibly primitive type of their init-form. ![]()
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