大约有 2,253 项符合查询结果（耗时：0.0585秒） [XML]
Performance surprise with “as” and nullable types
...d is of the expected type, takes but a few machine code instructions. The cast is also easy, the JIT compiler knows the location of the value bits in the object and uses them directly. No copying or conversion occurs, all machine code is inline and takes but about a dozen instructions. This neede...
Ignore Typescript Errors “property does not exist on value of type”
...erHtmlElement.getBBox();
###Edit, late 2016
Since TypeScript 1.6 prefered casting operator is as those lines can be squashed into:
let coordinates = (outerElement[0] as any).getBBox();
###Other solutions
Of course if you'd like to do it right, which is an overkill sometimes, you can:
Create own i...
How to loop through all enum values in C#? [duplicate]
...Foos));
Or the typed version:
var values = Enum.GetValues(typeof(Foos)).Cast<Foos>();
I long ago added a helper function to my private library for just such an occasion:
public static class EnumUtil {
public static IEnumerable<T> GetValues<T>() {
return Enum.GetVa...
How does std::move() transfer values into RValues?
...reference<T>::type&& move(T&& arg)
{
return static_cast<typename remove_reference<T>::type&&>(arg);
}
Let's start with the easier part - that is, when the function is called with rvalue:
Object a = std::move(Object());
// Object() is temporary, which ...
Cast an instance of a class to a @protocol in Objective-C
... [vc protocolMethod];
}
The UIViewController <MyProtocol> * type-cast translates to "vc is a UIViewController object that conforms to MyProtocol", whereas using id <MyProtocol> translates to "vc is an object of an unknown class that conforms to MyProtocol".
This way the compiler wil...
Converting bool to text in C++
...Boost that can help us out here. Boost has a nice function called lexical_cast. We can use it thus:
boost::lexical_cast<std::string>(my_bool)
Now, it's true to say that this is higher overhead than some macro; stringstreams deal with locales which you might not care about, and create a dy...
Does the 'mutable' keyword have any purpose other than allowing the variable to be modified by a con
....
Without the mutable keyword you will eventually be forced to use const_cast to handle the various useful special cases it allows (caching, ref counting, debug data, etc.). Unfortunately const_cast is significantly more destructive than mutable because it forces the API client to destroy the cons...
What is an “unwrapped value” in Swift?
...gift:getGift())
//Now we have to unwrap f00, unwrap its entry, then force cast it into the type we hope it is, and then repeat this in nested fashion until we get to the final value.
var b4r = (((((((((((f00![10]! as! [Int:Any?])[9]! as! [Int:Any?])[8]! as! [Int:Any?])[7]! as! [Int:Any?])[6]! as! ...
What are the main purposes of using std::forward and which problems it solves?
... modify these
The third attempt accepts const-references, but then const_cast's the const away:
template <typename A, typename B, typename C>
void f(const A& a, const B& b, const C& c)
{
E(const_cast<A&>(a), const_cast<B&>(b), const_cast<C&>(c))...
How to cast/convert pointer to reference in C++
...
Call it like this:
foo(*ob);
Note that there is no casting going on here, as suggested in your question title. All we have done is de-referenced the pointer to the object which we then pass to the function.
...