scope

问题 package main import "fmt" const name = "Yosua" // or var name string = "James" func main() { name := "Jobs" fmt.Println(name) } How to refer to the constant and not the the function level variable? 回答1: You can't. While the local variable name is in scope, the name name denotes the local variable. And there is no "qualifier" to refer to top-level identifiers. Spec: Declarations and scope: An identifier declared in a block may be redeclared in an inner block. While the identifier of the inner

问题 I'm trying to iterate over an array and assign a variable with a for loop. So something like this: function Person(name, status){ this.name = name; this.status = status; } var status = []; var array = ["bill","bob","carl","ton"]; function exAjax(function(){ for(var i = 0; i < array.length; i++){ var name = array[i]; console.log(name); =====> this gives the correct name $.ajax({ url: xxxxxxx, success: function(data){ if(data.stream === null){ var person = new Person(name, "dead"); console.log

问题 Once I assumed that these two have the same meaning but after reading more about it i'm still not clear about the difference. Doesn't the local scope sometimes refer to scope of function? and what does it mean that only labels have a function scope? 回答1: void doSomething() { <------- { <---- | | | int a; Local Scope Function Scope | | } <---- | } <------- Function Scope is between outer { } . Local scope is between inner { } Note that, any scope created by {``} can be called as the local

问题 Once I assumed that these two have the same meaning but after reading more about it i'm still not clear about the difference. Doesn't the local scope sometimes refer to scope of function? and what does it mean that only labels have a function scope? 回答1: void doSomething() { <------- { <---- | | | int a; Local Scope Function Scope | | } <---- | } <------- Function Scope is between outer { } . Local scope is between inner { } Note that, any scope created by {``} can be called as the local

问题 This is the code: class TestA { protected: int test=12; public: TestA() { cout << "test a: " << test << endl; } ~TestA() { } }; class TestB : public TestA { public: TestB(TestA *testA) { cout << "test b: " << testA->test; } ~TestB() { } }; int main () { TestA *pTestA=new TestA(); TestB *pTestB=new TestB(pTestA); } I'm trying to access of a protected member using a pointer pointing to a TestA type object (thus, an instance of TestA ). TestB is also derived from TestA Why I can't access to it?

问题 Why is it that curly braces do not define a separate local scope in Java? I was expecting this to be a feature common to the main curly brace languages (C, C++, Java, C#). class LocalScopeTester { public static void main(String... args) { Dog mine = new Dog("fido"); if (mine.getName().equals("ace")) { Dog mine = new Dog("spot"); // error: duplicate local } else { Dog mine = new Dog("barkley"); // error: duplicate local { Dog mine = new Dog("boy"); // error: duplicate local } } } } 回答1: They

问题 I've seen a few "solutions" to this, but the solution every time seems to be "Don't use nested classes, define the classes outside and then use them normally". I don't like that answer, because it ignores the primary reason I chose nested classes, which is, to have a pool of constants (associated with the base class) accessible to all sub-class instances which are created. Here is example code: class ParentClass: constant_pool = [] children = [] def __init__(self, stream): self.constant_pool

问题 What exactly is happening when I do: @patient.course_enrollments.accessible_by(current_ability) What seems to happen is I get course_enrollments where course.client_id = user.client.id , I just don't understand how accessible_by works. # ability.rb can :manage, CourseEnrollment, :course => {:client_id => user.client.id} 回答1: accessible_by gives you a scope that includes only those records which you'd be able to access given the current_ability . Since you stated that the :manage ability on

问题 I've got following code, that is suppose to pause Slidedeck's autoscroll whenever there is a mouseover event. For mouseout event, the autoscroll should resume working unless the youtobe video in the Slidedeck is currently playing or buffering. I got it working fine if there wasn't the condition for the Youtube video. I believe there's a problem with the scope for the object player, but can't work it out, how to fix this problem. The error I get in console on mouseout is: Uncaught TypeError:

问题 In Rust, in order to change the value of a mutable variable, what is the difference in let x = 12 or x = 12 in the following sample code? fn main() { let mut x: i32 = 8; { println!("{}", x); let x = 12; // what if change to x = 12 println!("{}", x); } println!("{}", x); let x = 42; println!("{}", x); } The output is 8, 12, 8, 42 . If I change let x = 12 to x = 12 ... fn main() { let mut x: i32 = 8; { println!("{}", x); x = 12; println!("{}", x); } println!("{}", x); let x = 42; println!("{}",