side-effects | 易学教程

Do toString side effects get applied in java debugging?

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问题 When debuggind java code in eclipse, if you click on one of the variable names, that object gets printed. The object's toString() method is used to print it. If some toString method has a side effect and I click on a variable of that type, will the side effects of its toString get applied (and doubtlessly mess everything up)? 回答1: I think you answered your own question. Any time you call toString , in debugging or otherwise, all side effects will occur. This is exactly why you should avoid

Side effects in C

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问题 I thought that my understanding of side effects in programming languages was OK. I think this is a great definition from wikipedia: "in addition to returning a value, it also modifies some state or has an observable interaction with calling functions or the outside world." However, I read this in the same link(yes, I know that is probably not the best place to look for examples): "One common demonstration of side effect behavior is that of the assignment operator in C++. For example,

Simple Vue.js Computed Properties Clarification

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问题 I'm not new to Vue.js, but I'm going through the docs again, trying to pick up on anything I missed the first time. I came across this statement in basic example section of using computed properties: You can data-bind to computed properties in templates just like a normal property. Vue is aware that vm.reversedMessage depends on vm.message , so it will update any bindings that depend on vm.reversedMessage when vm.message changes. And the best part is that we’ve created this dependency

Side effects in Scala

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问题 I am learning Scala right in these days. I have a slight familiarity with Haskell, although I cannot claim to know it well. Parenthetical remark for those who are not familiar with Haskell One trait that I like in Haskell is that not only functions are first-class citizens, but side effects (let me call them actions) are. An action that, when executed, will endow you with a value of type a , belongs to a specific type IO a . You can pass these actions around pretty much like any other value,

Why isn't mySet.erase(it++) undefined behavior, or is it?

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问题 Accordint to this quite highly upvoted answer, the canonical way to iterate through a set erasing some elements is the following: for (it = mySet.begin(); it != mySet.end(); ) { if (conditionToDelete(*it)) { mySet.erase(it++); } else { ++it; } } This, of course, is a result of C++03's set erase not returning an iterator. Otherwise one could write it = mySet.erase(it); It is also obvious that one can write itToDelete = it++; mySet.erase(itToDelete); This question is not about how to delete

Infinite loop with ngrx/effects

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问题 I'm trying to understand ngrx/effects. I have built a simple function that increments number by 1 with each click. But it's going in an infinite loop when clicked, not sure whats going on. I'm sure im making some stupid mistake. monitor.effects.ts @Injectable() export class MonitorEffects { @Effect() compute$: Observable<Action> = this.actions$ .ofType(monitor.ActionTypes.INCREMENT) .map((action: monitor.IncrementAction) => action.payload) .switchMap(payload => { return this.http.get('https:/

How to Document Java Side Effects

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问题 Is there a standard or best practice for writing javadocs for Java/JVM language methods which contain side effects? I have a void method defined, which modifies one of the method parameters, but do not know how to document the actual return value (since there is no actual return). /** * @param obj - reference object * @return obj - obj.name is changed to 'hello' //TODO figure out javadoc annotation */ void methodName(Object obj) { if (obj != null) { obj.name = "hello"; } } It just seems that

Unit testing functions with side effects?

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问题 Let's say you're writing a function to check if a page was reached by the appropriate URL. The page has a "canonical" stub - for example, while a page could be reached at stackoverflow.com/questions/123, we would prefer (for SEO reasons) to redirect it to stackoverflow.com/questions/123/how-do-i-move-the-turtle-in-logo - and the actual redirect is safely contained in its own method (eg. redirectPage($url)), but how do you properly test the function which calls it? For example, take the

“Side-effecting lexical closure” vs function in Scala

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问题 In his answer's comment section, Apocalisp states the following: Well, you did ask for a function. A side-effenting [sic] lexical closure is emphatically not a function. What exactly does he mean by "side-effecting lexical closure", and how is that different from a function? My guess is that they're trying to differentiate functions in a functional programming sense - where no side effects are allowed (such as changing state of variables or outputting values), from mere procedures , which do

Infinite loop with ngrx/effects

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I'm trying to understand ngrx/effects. I have built a simple function that increments number by 1 with each click. But it's going in an infinite loop when clicked, not sure whats going on. I'm sure im making some stupid mistake. monitor.effects.ts @Injectable() export class MonitorEffects { @Effect() compute$: Observable<Action> = this.actions$ .ofType(monitor.ActionTypes.INCREMENT) .map((action: monitor.IncrementAction) => action.payload) .switchMap(payload => { return this.http.get('https://jsonplaceholder.typicode.com/users') .map(data => new monitor.IncrementAction(payload+1)) .catch(err =