0.9.0

• More efficient implementation of variadic formatting functions.

• Writer::Format now has a variadic overload:

  Writer out;
  out.Format("Look, I'm {}!", "variadic");
  

• For efficiency and consistency with other overloads, variadic overload of the Format function now returns Writer instead of std::string. Use the str function to convert it to std::string:

  std::string s = str(Format("Look, I'm {}!", "variadic"));
  

• Replaced formatter actions with output sinks: NoAction -> NullSink, Write -> FileSink, ColorWriter -> ANSITerminalSink. This improves naming consistency and shouldn't affect client code unless these classes are used directly which should be rarely needed.

• Added ThrowSystemError function that formats a message and throws SystemError containing the formatted message and system-specific error description. For example, the following code

  FILE *f = fopen(filename, "r");
  if (!f)
      ThrowSystemError(errno, "Failed to open file '{}'") << filename;
  

  will throw SystemError exception with description "Failed to open file '<filename>': No such file or directory" if file doesn't exist.

• Support for AppVeyor continuous integration platform.

• Format now throws SystemError in case of I/O errors.

• Improve test infrastructure. Print functions are now tested by redirecting the output to a pipe.