Anyway, the problem is that I can’t really return just a single object from next(), and I also can’t have a Iterator take more than one type. So, any thoughts? Obviously you are going to need a light-weight “pair” class. This is roughly analogous to the Map.Entry inner class. Here’s a rough cut at a … Read more
I want to ignore all Err values Since Result implements IntoIterator, you can convert your Vec into an iterator (which will be an iterator of iterators) and then flatten it: Iterator::flatten: vec.into_iter().flatten().collect() Iterator::flat_map: vec.into_iter().flat_map(|e| e).collect() These methods also work for Option, which also implements IntoIterator. You could also convert the Result into an Option and … Read more
In list<tNode<T>*>::iterator, you have a dependant name, that is, a name that depends on a template parameter. As such, the compiler can’t inspect list<tNode<T>*> (it doesn’t have its definition at this point) and so it doesn’t know whether list<tNode<T>*>::iterator is either a static field or a type. In such a situation, the compiler assumes that … Read more
I prefer the for loop because it also sets the scope of the iterator to just the for loop.
The alternative to catching StopIteration is to use next(iterator, default_value). For example: >>> a = iter(‘hi’) >>> print(next(a, None)) h >>> print(next(a, None)) i >>> print(next(a, None)) None This way you can check for None to see if you’ve reached the end of the iterator if you don’t want to do it the exception way. … Read more
Use the old for loop as: for (auto it = values.begin(); it != values.end(); ++it ) { auto & value = *it; //… } With this, you’ve value as well as iterator it. Use whatever you want to use. EDIT: Although I wouldn’t recommended this, but if you want to use range-based for loop (yeah, … Read more
Calls to itertools.imap() in Python 2 or map() in Python 3 can be replaced by equivalent generator expressions: sum(1 for dummy in it) This also uses a lazy generator, so it avoids materializing a full list of all iterator elements in memory.
Here is one using DomDocument The basic idea is the contents of each directory is represented by a <ul> and each element in the directory by a <li> If element is a non-empty directory it will contain a <ul> to represent its contens and so on. $path = $_SERVER[‘DOCUMENT_ROOT’].’/test’; $objects = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($path), RecursiveIteratorIterator::SELF_FIRST); … Read more
The remove(int) method on List removes the element at the specified position. Before you start your loop, your list looks like this: [1, 2] Then you start an iterator on the list: [1, 2] ^ Your for loop then removes the element at position 1, which is the number 2: [1] ^ The iterator, on … Read more
As the book you linked to says: If you are trying to execute a closure on an iterator for its side effects, use for instead. That way it works, and it’s much clearer to anyone reading the code. You should use map when you want to transform a vector to a different one.