🎨 Style guide

Don't agonise about style - write your code as you see fit and we can address major issues in review/PR. Some encouraged conventions include:

• use camelCase for everything except:
  • constants which use CAPITALS_AND_UNDERSCORES
  • related function prefixes, like prefix_someFunction()
• favour clarity over concision, for example

  qcomp elem = state[ind][ind];
  qreal prob = std::real(elem);
  return prob;
  

  over

  return std::real(state[ind][ind]);
  

• never ever do:

  using namespace std;
  

  but do shorten common containers like vector:

  using std::vector;
  
  vector<int> mylist;
  

• whitespace is free; use it wherever it can improve clarity, like to separate subroutines.

  // i000 = nth local index where all suffix bits are 0
  qindex i000 = insertThreeZeroBits(n, braQb1, ketQb2, ketQb1);
  qindex i0b0 = setBit(i000, ketQb2, braBit2);
  qindex i1b1 = flipTwoBits(i0b0, braQb1, ketQb1);
  
  // j = nth received amp in buffer
  qindex j = n + offset;
  
  // mix pair of amps using buffer
  qcomp amp0b0 = qureg.cpuAmps[i0b0];
  qcomp amp1b1 = qureg.cpuAmps[i1b1];
  
  qureg.cpuAmps[i0b0] = c1*amp0b0 + c2*(amp1b1 + qureg.cpuCommBuffer[j]);
  qureg.cpuAmps[i1b1] = c1*amp1b1 + c2*(amp0b0 + qureg.cpuCommBuffer[j]);
  

• use auto where it improves readability, discretionarily. Obviously it is better than massive, unimportant types of objects or heavily templated collections, but sometimes knowing the precise type of a primitive is helpful
• It is permissable to avoid superfluous braces around single-line branches:

  if (cond)
      return x;
  

• always prefix calls to mathematical functions like abs() with the std namespace, i.e. std::abs(). This avoids ambiguity with C overloads like abs(int) which can cause insidious bugs! The full list of functions to prefix are:
  • abs
  • real
  • imag
  • conj
  • norm
  • sin
  • cos
  • log
  • log2
  • exp
  • pow
  • sqrt
  • floor
  • ceil
  • atan2
  • min
  • max