definition

问题 Recently I tried to Access a textbox from a thread (other than the UI thread) and an exception was thrown. It said something about the "code not being thread safe" and so I ended up writing a delegate (sample from MSDN helped) and calling it instead. But even so I didn't quite understand why all the extra code was necessary. Update: Will I run into any serious problems if I check Controls.CheckForIllegalCrossThread..blah =true 回答1: Eric Lippert has a nice blog post entitled What is this thing

问题 The C standard states: If the declaration of an identifier for an object is a tentative definition and has internal linkage, the declared type shall not be an incomplete type What does it mean that "the declared type shall not be an incomplete type"? 回答1: That means you are not allowed to have: static int arr[]; // This is illegal as per the quoted standard. int main(void) {} The array arr is tentatively defined and has an incomplete type (lacks information about the size of the object) and

问题 How can I know whether to use def, cdef or cpdef when defining a Cython function, assuming I want optimal performance? 回答1: If you want optimal performance, you should know that as mentioned in this answer to a related question: Once the function has been called there is no difference in the speed that the code inside a cdef and a def function runs at. So for optimal Cython performance you should always statically type all arguments and variables , and intuitively you would then be tempted to

问题 I write code below: let array1: [Int] = [0,1] let array2 = array1 + [2] It just works.I want to find where + operator define. I search ArrayExtension in my workspace without result.I search Apple doc Collection Sequence Array , there is no result. Is there a way to navigate to operator definition ,like CMD + CTRL + J for func 回答1: You can select the operator in the Xcode source editor, and choose "Navigate -> Jump to definition" from the menu, or press CMD+CTRL+J. (This was broken in Xcode 10

问题 I am currently studying about REST interfaces for directory services and I'm confused about RESTful interfaces. When can we say that the design is completely RESTful? 回答1: The REST architectural style REST stands for Re presentational S tate T ransfer. This architecture is protocol independent but it is frequently implemented over the HTTP protocol. The REST architectural style was defined in the chapter 5 of Roy Thomas Fielding's PhD dissertation. And the following set of constraints was

问题 This question already has answers here : Where and why do I have to put the “template” and “typename” keywords? (6 answers) Closed 2 years ago . There's a template function f that requires its template parameter type T to have an inner class named Inner . Inside f the class T::Inner shall be instantiated. First try. // // "error: need 'typename' before 'T:: Inner' because 'T' is a dependent scope" // template <typename T> void f( void ) { T::Inner i; } I get that, so here comes the second try

问题 A quick question I hope. I would like to know why the line commented out below causes an error when placed at the global level while it works fine when placed inside the main function? Many Thanks #include <iostream> using namespace std; bool compare(const int &v1, const int &v2) { if (v1 < v2) { return true; } else { return false; } } bool (*pf5)(const int &v1, const int &v2); //pf5 = compare; int main() { int v1 = 5; int v2 = 6; pf5 = compare; bool YesNo1 = compare(v1, v2); cout << YesNo1 <

问题 Is there a way to add a description to my methods in Xcode iOS project so I can see quick details when clicking on a desired method with OPTION + click like it can be done on Apple's API's methods (case bellow)? Thanks! 回答1: If I understand right than all of this tools are for generating documentation and not for adding method's description. Am I right? 来源： https://stackoverflow.com/questions/10530695/show-method-definition-description-in-xcode-4

问题 For the following code, why does the first case in main work fine without the redeclaration of Foo::bar, whereas the second case with the function requires it? struct Foo{ static constexpr int bar = 30; }; //Declaration of Foo::bar outside of struct constexpr int Foo::bar; int returnconstexpr(const int& x) { return x; } int main() { //Ok without declaration outside of struct std::cout << Foo::bar << std::endl; //Requires declaration outside of struct std::cout << returnconstexpr(Foo::bar) <<

问题 Do I need to declare all functions I use in a .c file in a header file, or can I just declare and define right there in the .c file? If so, does a definition in the .c file in this case count as the declaration also? 回答1: For the compiler, it does not matter if a declaration occurs in a .h or a .c file, because the compiler sees the preprocessed form. For the human developer reading and contributing to your code, it is much better (to avoid copy&pasting the same declaration twice) to put the