definition

Consider this code: #include <vector> struct A { static constexpr int kDefaultValue = -1; std::vector<int> v; A(int n): v(n, A::kDefaultValue) {} }; int main() { A(10); return 0; } It fails to link (llvm clang, gcc 4.9, both on OS X): Undefined symbols for architecture x86_64: "A::kDefaultValue", referenced from: A::(int) in main.cpp.o ld: symbol(s) not found for architecture x86_64 The question is what's wrong with it? It can be fixed by static_cast -ing A::kDefaultValue to int . Or by moving kDefaultValue out of A . Both cases seem to be ugly. Is this another way to make it link? This

I found this line in stdio.h : extern struct _IO_FILE *stdin; Based on this 'extern' keyword, i assume this is just a declaration. I wonder where is stdin defined and initialized? It's defined in the source code of your C library. You typically only need the headers for compilation, but you can find the source code for many open-source standard libraries (like glibc). In glibc, it's defined in libio/stdio.c as like this: _IO_FILE *stdin = (FILE *) &_IO_2_1_stdin_; Which is in turn defined using a macro in libio/stdfiles.c like this: DEF_STDFILE(_IO_2_1_stdin_, 0, 0, _IO_NO_WRITES); The

In vim, in my .vimrc, how can I redefine a command (i.e. :e) as something else? I want to redefine :e * as :tabe * . Yktula I figured out a way to do it. See How to disable a built-in command in vim . From that, we can see that we can use cabbrev to change what a command does. For my needs, cabbrev e tabe is perfect. But we can generalize this solution to make commands starting with lower case characters accessible to users for user-defined ones: use cabbrev to (re)define a built-in command as a user-defined one. As such, we are able to redefine built-in commands as well as user-defined ones.

I have come across Java code in this form for the first time: object.methodA(new ISomeName() { public void someMethod() { //some code } }); Where ISomeName is an interface that has one method with the same signature as someMethod() above. From what I can understand, we are defining a new nameclass class that implements ISomeName, creating an object of this class using default constructor and passing the object as an argument to methodA. Is this right? What is the name of this feature? It's creating an anonymous class . Note that within anonymous class, you can refer to final local variables

This is a follow-up question. In the previous question , @JohannesSchaub-litb said that the following code is not fully standard-conformant: class { int i; }; //unnamed-class definition. § 9/1 allows this! and then he added, while it is grammatically valid, it breaks the rule that such a class must declare at least one name into its enclosing scope. I couldn't really understand this. What name is he talking about? Could anyone elaborate on this further (preferably quoting the Standard)? Clause 9 of the standard allows class {public: int i;} (note the lack of a final semicolon) because this