Recursion is just a way of thinking, just as iterative is. When we were kids at school, we weren’t taught to think recursively and there lies the real problem. You need to incorporate that way of thinking into your arsenal, once you do it, it’ll stay there forever. Best way to master: I found useful … Read more
Shepmaster’s answer explains that tail call elimination is merely an optimization, not a guarantee, in Rust. But “never guaranteed” doesn’t mean “never happens”. Let’s take a look at what the compiler does with some real code. Does it happen in this function? As of right now, the latest release of Rust available on Compiler Explorer … Read more
when you recurse, you need to return the result of _finditem def _finditem(obj, key): if key in obj: return obj[key] for k, v in obj.items(): if isinstance(v,dict): return _finditem(v, key) #added return statement To fix the actual algorithm, you need to realize that _finditem returns None if it didn’t find anything, so you need to … Read more
PaulR has the right suggestion. You have to run through the code by “hand” (using whatever tools you want – debuggers, paper, logging function calls and variables at certain points) until you understand it. For an explanation of the code I’ll refer you to quasiverse’s excellent answer. Perhaps this visualization of the call graph with … Read more
The trampoline is just a technique to optimize recursion and prevent stack-overflow exceptions in languages that don’t support tail call optimization like Javascript ES5 implementation and C#. However, ES6 will probably have support for tail call optimization. The problem with regular recursion is that every recursive call adds a stack frame to the call stack, … Read more
oke this is how i solved it: $arr = array( array(‘id’=>100, ‘parentid’=>0, ‘name’=>’a’), array(‘id’=>101, ‘parentid’=>100, ‘name’=>’a’), array(‘id’=>102, ‘parentid’=>101, ‘name’=>’a’), array(‘id’=>103, ‘parentid’=>101, ‘name’=>’a’), ); $new = array(); foreach ($arr as $a){ $new[$a[‘parentid’]][] = $a; } $tree = createTree($new, array($arr[0])); print_r($tree); function createTree(&$list, $parent){ $tree = array(); foreach ($parent as $k=>$l){ if(isset($list[$l[‘id’]])){ $l[‘children’] = createTree($list, $list[$l[‘id’]]); } … Read more
Iterators do not work recursively like that. You have to re-yield each result, by replacing explore(path) with something like for value in explore(path): yield value Python 3.3 added the syntax yield from X, as proposed in PEP 380, to serve this purpose. With it you can do this instead: yield from explore(path) If you’re using … Read more
Yes, actually you can take some code and convert every function call—and every return—into a tail call. What you end up with is called continuation-passing style, or CPS. For example, here’s a function containing two recursive calls: (define (count-tree t) (if (pair? t) (+ (count-tree (car t)) (count-tree (cdr t))) 1)) And here’s how it … Read more
Try like this: public static MvcHtmlString Try<TModel, TProperty>( this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression ) { var builder = new TagBuilder(“textarea”); builder.AddCssClass(“ckeditor”); builder.MergeAttribute(“cols”, “80”); builder.MergeAttribute(“name”, “editor1”); builder.MergeAttribute(“id”, expression.Name); // not sure about the id – verify var value = ModelMetadata.FromLambdaExpression( expression, htmlHelper.ViewData ).Model; builder.SetInnerText(value.ToString()); return MvcHtmlString.Create(builder.ToString()); }
For people actually wanting a direct answer to this question (instead of being told to use something other than sftp)… put -r local/path/to/directoryName The uploaded directory must already exist in the working directory on the server, so you might need to create it first. mkdir directoryName