Re: [PATCH 19/22] sequencer: support cleaning up commit messages

Hello Johannes,

W dniu 01.09.2016 o 15:56, Johannes Schindelin pisze: 

On Thu, 1 Sep 2016, Jakub Narębski wrote:

quoted

It's a pity that emulation of named parameters in C requires
relying on designated inits from C99

  typedef struct {
    double pressure, moles, temp;
  } ideal_struct;

  #define ideal_pressure(...) ideal_pressure_base((ideal_struct){.pressure=1,   \
                                        .moles=1, .temp=273.15, __VA_ARGS__})

  double ideal_pressure_base(ideal_struct in)
  {
    return 8.314 * in.moles*in.temp/in.pressure;
  }

  ... ideal_pressure(.moles=2, .temp=373.15) ...

Forgot to add citation:

[1] Ben Klemens "21st Century C: C Tips from the New School", 2nd Ed. (2014),
    O'Reilly Media, chapter 10. "Better Structures", subsection
    "Optional and Named Arguments"

Yeah, that looks unwieldy ;-)

Declaration needs some trickery, but use is much, much more readable
(if we cannot use sensibly named variables for passing arguments):

  ideal_pressure()
  ideal_pressure(.temp=373.15)
  ideal_pressure(.moles=2)
  ideal_pressure(.moles=2, .temp=373.15) 

It is even better if there are large amount of parameters:

  res = amortization(.amount=200000, .inflation=3,
                     .show_table=0, .extra_payoff=100)

vs

  double amortize(double amt, double rate, double inflation, int months,
            int selloff_month, double extra_payoff, int verbose,
            double *interest_pv, double *duration, double *monthly_payment);

 
But we can't use it in Git, anyway
-- 
Jakub Narębski