Forward declaration of nested types/classes in C++
You can’t do it, it’s a hole in the C++ language. You’ll have to un-nest at least one of the nested classes.
nested
Can regular expressions be used to match nested patterns? [duplicate]
No. It’s that easy. A finite automaton (which is the data structure underlying a regular expression) does not have memory apart from the state it’s in, and if you have arbitrarily deep nesting, you need an arbitrarily large automaton, which collides with the notion of a finite automaton. You can match nested/paired elements up to … Read more
How to query nested objects?
db.messages.find( { headers : { From: “reservations@marriott.com” } } ) This queries for documents where headers equals { From: … }, i.e. contains no other fields. db.messages.find( { ‘headers.From’: “reservations@marriott.com” } ) This only looks at the headers.From field, not affected by other fields contained in, or missing from, headers. Dot-notation docs
Comprehension on a nested iterables?
Here is how you would do this with a nested list comprehension: [[float(y) for y in x] for x in l] This would give you a list of lists, similar to what you started with except with floats instead of strings. If you want one flat list then you would use [float(y) for x in … Read more
Nested routes with react router v4 / v5
In react-router-v4 you don’t nest <Routes />. Instead, you put them inside another <Component />. For instance <Route path=”/topics” component={Topics}> <Route path=”/topics/:topicId” component={Topic} /> </Route> should become <Route path=”/topics” component={Topics} /> with const Topics = ({ match }) => ( <div> <h2>Topics</h2> <Link to={`${match.url}/exampleTopicId`}> Example topic </Link> <Route path={`${match.path}/:topicId`} component={Topic}/> </div> ) Here is a … Read more
How to use a dot “.” to access members of dictionary?
I’ve always kept this around in a util file. You can use it as a mixin on your own classes too. class dotdict(dict): “””dot.notation access to dictionary attributes””” __getattr__ = dict.get __setattr__ = dict.__setitem__ __delattr__ = dict.__delitem__ mydict = {‘val’:’it works’} nested_dict = {‘val’:’nested works too’} mydict = dotdict(mydict) mydict.val # ‘it works’ mydict.nested = … Read more
Nested select statement in SQL Server
You need to alias the subquery. SELECT name FROM (SELECT name FROM agentinformation) a or to be more explicit SELECT a.name FROM (SELECT name FROM agentinformation) a
Margin on child element moves parent element
Found an alternative at Child elements with margins within DIVs You can also add: .parent { overflow: auto; } or: .parent { overflow: hidden; } This prevents the margins to collapse. Border and padding do the same. Hence, you can also use the following to prevent a top-margin collapse: .parent { padding-top: 1px; margin-top: -1px; … Read more
Accessing nested JavaScript objects and arrays by string path
I just made this based on some similar code I already had, it appears to work: Object.byString = function(o, s) { s = s.replace(/\[(\w+)\]/g, ‘.$1’); // convert indexes to properties s = s.replace(/^\./, ”); // strip a leading dot var a = s.split(‘.’); for (var i = 0, n = a.length; i < n; ++i) … Read more
Test for existence of nested JavaScript object key
You have to do it step by step if you don’t want a TypeError because if one of the members is null or undefined, and you try to access a member, an exception will be thrown. You can either simply catch the exception, or make a function to test the existence of multiple levels, something … Read more