The C-Preprocessor is a very powerful mechanism, which offers many different features. One of these features is called Variadic macros: macros that accept a varying number of arguments. It is interesting to note at this point, that such Variadic macros, despite being part of the C99 Standard, are not part of the C++ Standard at the moment. However, a big number of C++ compilers support it nevertheless.
While allowing the definition of Variadic macros, there is no built-in (preprocessor) way of obtaining the actual number of arguments that is passed to a specific Variadic macro. In this post we shall provide a possible macro implementation for such a query.
Continue reading Variadic macro to count number of arguments
In the concurrent world, a Future object refers to an object whose actual value is to be computed in the future. You can think of it as a handle to an asynchronous invocation of a computation that yields a value.
Many so called concurrent programming languages support this idea as a native construct offered by the core language itself. Unfortunately, C++ does not. Well, at least not in the current standard; C++0x (or shall I say C++1x ?) is going to support std::future as part of the massive new C++0x thread library, which is based on boost::thread. In this post we will implement a simple, yet very powerful, such future object.
Continue reading Futures: asynchronous invocation
A Quine is a computer program which prints a copy of its own source code as its only output.
Thus it is theoretically possible to compile such a program, run it, and then have its output compiled again to produce the initial program – in an infinite loop, forever.
Continue reading Quines
The handler std::terminate() is called whenever the exception handling mechanism cannot find a suitable catch clause for a thrown exception (and in some other cases. For example, when an exception is thrown during the handling of another exception – see this GotW post about std::uncaught_exception). It is possible to define a custom handler by using std::set_terminate.
In this post we would like to create a terminate handler which will be able to catch the exception that led to its invocation, when there is one.
Continue reading Catching uncaught exceptions within terminate
The possibility of overloading just about any C++ operator and having it do something entirely different from what it was designed for, can sometimes make life pretty hard.
Here are a couple of examples: What if you wanted to take the address of an object, which had implemented an entirely different semantic for the ampersand (&) operator? Or what if somebody decided to overload the comma operator in some strange manner?
As you could have guessed, there are solutions for such scenarios.
Continue reading Escaping overloaded operators