C++ style

We generally follow Google C++ Style Guide.

Naming

Variable names should consist of lowercase words connected by underscores, e.g. llvm_context.
Class and struct names should consist of words with first letters capitalized, e.g. CodegenLLVM.
Macros should be capital start with TI, such as TI_INFO, TI_IMPLEMENTATION.
- We do not encourage the use of macro, although there are cases where macros are inevitable.
Filenames should consist of lowercase words connected by underscores, e.g. ir_printer.cpp.

Dos

Use auto for local variables when appropriate.
Mark override and const when necessary.

Don'ts

C language legacies:
- printf (Use fmtlib::print instead).
- new and free. (Use smart pointers std::unique_ptr, std::shared_ptr instead for ownership management).
- #include <math.h> (Use #include <cmath> instead).
Exceptions (We are on our way to remove all C++ exception usages in Taichi).
Prefix member functions with m_ or _.
Virtual function call in constructors/destructors.
NULL (Use nullptr instead).
using namespace std; in the global scope.
typedef (Use using instead).

Automatic code formatting

Please run ti format