Either is fine. They both run lazily – if the source list has a million items, but the tenth item matches then both will only iterate 10 items from the source. Performance should be almost identical and any difference would be totally insignificant.
This is really just a syntax switch. OK, so we have this method call: [NSPredicate predicateWithFormat:@”name contains[c] %@”, searchText]; In Swift, constructors skip the “blahWith…” part and just use the class name as a function and then go straight to the arguments, so [NSPredicate predicateWithFormat: …] would become NSPredicate(format: …). (For another example, [NSArray arrayWithObject: … Read more
From Predicate Programming Guide: You specify and test for equality of Boolean values as illustrated in the following examples: NSPredicate *newPredicate = [NSPredicate predicateWithFormat:@”anAttribute == %@”, [NSNumber numberWithBool:aBool]]; NSPredicate *testForTrue = [NSPredicate predicateWithFormat:@”anAttribute == YES”]; You can also check out the Predicate Format String Syntax.
I’m assuming you’re talking about com.google.common.base.Predicate<T> from Guava. From the API: Determines a true or false value for a given input. For example, a RegexPredicate might implement Predicate<String>, and return true for any string that matches its given regular expression. This is essentially an OOP abstraction for a boolean test. For example, you may have … Read more
It’s “just sugarcoating” for readability, but they do have common meanings: Methods ending in ! perform some permanent or potentially dangerous change; for example: Enumerable#sort returns a sorted version of the object while Enumerable#sort! sorts it in place. In Rails, ActiveRecord::Base#save returns false if saving failed, while ActiveRecord::Base#save! raises an exception. Kernel::exit causes a script … Read more
Javascript is single threaded, hence the page blocking behaviour. You can use the deferred/promise approach suggested by others. The most basic way would be to use window.setTimeout. E.g. function checkFlag() { if(flag === false) { window.setTimeout(checkFlag, 100); /* this checks the flag every 100 milliseconds*/ } else { /* do something*/ } } checkFlag(); Here … Read more
Predicate: essentially Func<T, bool>; asks the question “does the specified argument satisfy the condition represented by the delegate?” Used in things like List.FindAll. Action: Perform an action given the arguments. Very general purpose. Not used much in LINQ as it implies side-effects, basically. Func: Used extensively in LINQ, usually to transform the argument, e.g. by … Read more
There are no built-in always-true and always-false predicates in Java 8. The most concise way to write these is x -> true and x -> false Compare these to Predicates.alwaysTrue() // Guava and finally to an anonymous inner class: new Predicate<Object>() { public boolean test(Object x) { return true; } } Probably the reason that … Read more
Predicate<T> is a functional construct providing a convenient way of basically testing if something is true of a given T object. For example suppose I have a class: class Person { public string Name { get; set; } public int Age { get; set; } } Now let’s say I have a List<Person> people and … Read more
Would the dynamic linq library help here? In particular, I’m thinking as a Where clause. If necessary, put it inside a list/array just to call .Where(string) on it! i.e. var people = new List<Person> { person }; int match = people.Where(filter).Any(); If not, writing a parser (using Expression under the hood) isn’t hugely taxing – … Read more