reference

问题 I want to link the doctrine orm entity and doctrine odm document and use them in sonataAdminBundle in configureFormFields Method of the Admin Class. I've established the @Gedmo\References doctrine-extension and it works just fine when i'm trying to access the linked models from controller. But now I need to do it from SonataAdminBundle - to make an UI to add the linked documents to the user entity. Here is my entity: <?php namespace Application\Sonata\UserBundle\Entity; use Doctrine\ORM

问题 Getting some really confusing errors and not sure exactly why. Here is my code: //=====================WORKS======================= TradingBook::TradingBook(const char* yieldCurvePath, const char* bondPath) { //...Some stuff BaseBond* tradingBook[bondCount]; for (int i=0; i < bondCount; i++) { tradingBook[i] = new CouponBond(bonds[i]); printf("Bond: %s\n" " Price: %.3f\n" " DV01: %.3f\n" " Risk: %.3f\n", tradingBook[i]->getID(), tradingBook[i]->getPrice(), tradingBook[i]->getDV01(),

问题 I am puzzled between two syntaxes to access references from the react documentation...All i want to know is when to use inputRef.current to access a reference instead of this.inputRef in react 回答1: When the reference is created using React.creatRef() a React 16 syntax then you can access it using current property of reference i.e inputRef.current. React.createRef() class User extends Component{ constructor(props){ super(); this.nameField = React.createRef(); this.onClick = this

问题 I'm playing a bit with the Net::Amazon::EC2 libraries, and can't find out a simple way to print object properties: This works: my $snaps = $ec2->describe_snapshots(); foreach my $snap ( @$snaps ) { print $snap->snapshot_id . " " . $snap->volume_id . "\n"; } But if I try: print "$snap->snapshot_id $snap->volume_id \n"; I get Net::Amazon::EC2::Snapshot=HASH(0x4c1be90)->snapshot_id Is there a simple way to print the value of the property inside a print? 回答1: Not in the way you want to do it. In

问题 I am using delphi 2009 and VCL components. I have created a collection called TStreets made of items TStreet which has just two private fields. Now I need to add to Tstreet class another field/property to keep track (by using reference) of other objects of class TMyObject. An example: let's assume that TStreet collection contains five elements and ten objects (TMyObject) exists in my application at run-time. Each objects of TMyObject can belong to only one TStreet so I need to save for each

问题 In the code below, I want to retain number_list , after iterating over it, since the .into_iter() that for uses by default will consume. Thus, I am assuming that n: &i32 and I can get the value of n by dereferencing. fn main() { let number_list = vec![24, 34, 100, 65]; let mut largest = number_list[0]; for n in &number_list { if *n > largest { largest = *n; } } println!("{}", largest); } It was revealed to me that instead of this, we can use &n as a 'pattern': fn main() { let number_list =

问题 This question already has answers here : How come a non-const reference cannot bind to a temporary object? (11 answers) Closed 5 years ago . Why reference can not capture temporary value while const reference and rvalue reference can capture and prolong object life. In other words while two first lines are legal but third not: const string &a = string("a"); string &&b = string("b"); string &c = string("c"); // why illegal? 回答1: Quoting from N1377 Bjarne in his excellent text "The Design and

问题 I have the following problem: I have interfaces IA in the ProjectA.dll and IB in the ProjectB.dll ( IB inherits IA ). When I try to implement IB in any another project the both references are required. Well, the requirement of a reference on the ProjectB.dll is expected, but I was little bit confused, that a reference on the ProjectA.dll is needed too. Does anybody know how is this feature called and where can I find detailed information about this behavior? 回答1: You'll need a reference to

问题 At first I thought arr.slice(0) was doing a deep unreferenced copy, but it is actually doing just a shallow unreferenced copy, so if the array contains nested arrays, they are still referenced: var a = [1,2] var b = [3,4] var c = [a,b] var d = c.slice(0) d[0] === a // true, which means it is the /same/ object d[0][0] = "Hi!" a // ["Hi!", 2] (example source) The solution on the links provided is fairly easy when you know the structure of the array (just .slice(0) ing again the nested arrays

问题 public class Hi { private final Map<String, String> map; public Map<String, String> getMap() { return map; } } I have this Hi class, and I want map to be immutable. I also need a getter. Currently, another class can modify the map from the getter. I would like to return a copy of the map to solve this problem, but Map is an interface, so does that mean I have to make the getter call: return new HashMap<String,String>(map); Is there another way to do it without forcing the map to be a hashmap?