callable - w3toppers.com

In c++ 11, how to invoke an arbitrary callable object?

Rather than implementing INVOKE yourself, use one of the library features that uses it. In particular, std::reference_wrapper works. Thus you can have the effect of std::invoke(f, args…) with std::ref(f)(args…): template<typename F, typename… Args> auto invoke(F f, Args&&… args) -> decltype(std::ref(f)(std::forward<Args>(args)…)) { return std::ref(f)(std::forward<Args>(args)…); } I didn’t forward f because std::reference_wrapper requires that the object passed … Read more

RestTemplate should be static globally declared?

It doesn’t matter either way, static or instance. RestTemplate‘s methods for making HTTP requests are thread safe so whether you have a RestTemplate instance per Task instance or a shared instance for all Task instances is irrelevant (except for garbage collection). Personally, I would create the RestTemplate outside the Task class and pass it as … Read more

How can I wrap a method so that I can kill its execution if it exceeds a specified timeout?

You should take a look at these classes : FutureTask, Callable, Executors Here is an example : public class TimeoutExample { public static Object myMethod() { // does your thing and taking a long time to execute return someResult; } public static void main(final String[] args) { Callable<Object> callable = new Callable<Object>() { public Object … Read more

What is a “callable” in Python?

A callable is anything that can be called. The built-in callable (PyCallable_Check in objects.c) checks if the argument is either: an instance of a class with a __call__ method or is of a type that has a non null tp_call (c struct) member which indicates callability otherwise (such as in functions, methods etc.) The method … Read more

Why does code like `str = str(…)` cause a TypeError, but only the second time?

Where the code says: global str str = str(parameter) You are redefining what str() means. str is the built-in Python name of the string type, and you don’t want to change it. Use a different name for the local variable, and remove the global statement. Note that if you used code like this at the … Read more

Odd method call in java using a dot operator to access a generic list

You more often think of classes as being generic, but methods can be generic too. A common example is Arrays.asList. Most of the time, you don’t have to use the syntax with angle brackets <…>, even when you’re invoking a generic method, because this is the one place in which the Java compiler is actually … Read more

TypeError: ‘list’ object is not callable while trying to access a list

For accessing the elements of a list you need to use the square brackets ([]) and not the parenthesis (()). Instead of: print wordlists(len(words)) you need to use: print worldlists[len(words)] And instead of: (wordlists(len(words))).append(words) you need to use: worldlists[len(words)].append(words)

Why do I get “TypeError: ‘str’ object is not callable” with this code?

This is the problem: global str str = str(mar) You are redefining what str() means. str is the built-in Python name of the string type, and you don’t want to change it. Use a different name for the local variable, and remove the global statement. Note that if you used code like this at the … Read more

The difference between the Runnable and Callable interfaces in Java

See explanation here. The Callable interface is similar to Runnable, in that both are designed for classes whose instances are potentially executed by another thread. A Runnable, however, does not return a result and cannot throw a checked exception.