deferred

Library for creating deferred evaluation expressions in C++.

deferred provides:

• functions to declare constants and variables,
• functions to create deferred evaluation expressions from functions,
• deferred-enabled commonly used operators.

Requirements

• C++17 capable compiler.
• CMake 3.8 and higher.

Compilers tested:

• Clang 8.0.0
• gcc 8.2.0

Installation

Copy include/deferred and include it in your compiler line with the -I flag.

Documentation

Generate documentation with make documentation from your build directory.

Usage

// examples/trivial/main.cpp
#include <iostream>
#include <deferred/deferred.hpp>
    
int main()
{
  auto v = deferred::variable<int>();
  auto x = deferred::constant(2);
  auto y = deferred::constant(3);

  auto expression = (v * x) + y;
  
  v = 10;
  
  auto res = expression();
  std::cout << res << "==" << (10 * 2) + 3 << '\n';
  return 0;
}

Examples can be found in the examples/ directory. They are compiled by default.

Testing

Tests are written using Catch2.

Known Issues

• Using callable objects and functions with side-effects in invoke() and if_then_else() will result in a constant expression, assignable to constant_.
• Using deferred with other expression template based classes (e.g., std::valarray) may not be possible.