nested

问题 While implementing a design using nested generic collections, I stumbled across those limitations apparently caused by C#'s invariant Generics: Cannot convert from 'Collection<subtype of T> to 'Collection<T>' That means, the following will not work, apparently due to the invariance of Generics: class Outer<TInner, TInnerItem> where TInner : Inner<TInnerItem> { public void Add(TInner item) { item.Outer = this; // ERROR: // Cannot implicitly convert from Outer<TInner, TInnerItem> // to Outer

问题 There are other questions referring to this on Stack Overflow such as how-to-parse-a-string-and-return-a-nested-array? But they all refer to lists in the format of ((abc)de(fg))) . going to the form: [['a','b','c']'d','e'['f','g',]]] I have a list of the form: ((wordOneWord2)OtherWord(FinalWord))) By using the methods I learnt from the other questions by nested list was of the form: [['w','o','r','d','O','n','e','W','o','r','d','2']'O','t','h','e','r','W','o','r','d',['F','i','n','a','l','W',

问题 My problem is as follows. This is my method: template<class T> T my_function(); These specializations work ok: template<> int my_function(); //my_function<int>(); template<> float my_function(); //my_function<flot>(); ... But these don't: 1. template<> template<class T> std::list<T> my_function(); //my_function<std::list<class T> >(); 2. template<class T> template<> std::vector<T> my_function(); //my_function<std::vector<class T> >(); I get the error: too many template-parameter-lists so my

问题 I have two data.frames--one look-up table that tells me a set products included in a group. Each group has at least one product of Type 1 and Type 2. The second data.frame tells me details about the transaction. Each transaction can have one of the following products: a) Only product s of Type 1 from one of the groups b) Only product s of Type 2 from one of the groups c) Product of Type 1 and Type 2 from the same group For my analysis, I am interested in finding out c) above i.e. how many

问题 I have the following nested function: int main() { int a, b, c; a = 10; int foo() { int a, b, c; //some more code here } // some more code here } Now, I need to assign the variable a that belongs to foo() , with the value of the variable a that belongs to main() . Basically, something like foo.a = main.a is what I'm looking for. Is there any way of doing this kind of assignment? I read through scope rules here and here , but didn't find anything I could use in this situation. I know that

问题 I am trying to create a C function called Dfetch() that is registered in Lua as fetch(). I am looking for it to be tiered such that I can call dog.beagle.fetch() as the function from Lua. It just helps with the organization of the code better. Below is what I have, but it is not calling my C function. If I just do the global and not the subtable, the C function gets called. I am new to Lua, so I think I am just setting up the tables wrong. void myregister(lua_State *L, const char *libname,

问题 This is a simple problem that I've been trying to solve for several hours. I have an array containing information of several students and marks they scored in tests. There are 8 subjects in total, with each subject having 5 parameters. The array looks like below: Array ( [Ron] => Array ( [subject1] => Array ( [test1] => 47 [test2] => 86 [total] => 133 [percentage] => 88.67 [status] => Pass ) [pass_count] => 8 [fail_count] => 0 [gross_total] => 963 [gross_percentage] => 80.25 [...] [subject8]

问题 When you need to check/have combinations of array elements, how can you avoid nesting foreach? Example code: $as = array($optionA1, $optionA2) $bs = array($optionB1, $optionB2) $cs = array($optionC1, $optionC2) foreach ($as as $a) { foreach ($bs as $b) { foreach ($cs as $c) { $result = $this->method($a, $b, $c); if ($result) etc } } } Anyone with alternative approaches that can avoid nesting? 回答1: You could write your own Iterator class which implements the Iterator interface. You could then

问题 I use an array to store a list of group objects and an array of a list of light objects. I want to show the first group in the html and all connected lights to that group. After that the next group and the related lights and so on.... <div> <ul> <li *ngFor="let group of hueGroups"> {{group.name}} <li *ngFor="let light of hueLights; let i = index"> {{hueLights[group.lights[i]].name}} </li> </ul> </div> export class AppComponent implements OnInit { hueGroups:any[]; hueLights:any[]; constructor(

问题 I have a List<List<string>> called _DataCollection where each of the nested lists have an equal number of values. Although all strings, the values in the nested lists will be strings consisting of alphanumeric characters, empty strings, or a currency value. For example _DataCollection[0] = {"tom", "abc", "$525.34", "$123"} _DataCollection[1] = {"dick", "xyz", "$100", "$234"} _DataCollection[2] = {"harry", "", "$250.01", "$40"} _DataCollection[2] = {"bob", "", "$250.01", ""} What I need to do