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

From: Jakub Narębski <jnareb@gmail.com>
Date: Sep 1, 2016, 23:31 UTC
Message-ID: <80a779a5-70d3-64dc-d206-41c47e1c69f5@gmail.com>
In-Reply-To: <alpine.DEB.2.20.1609011543290.129229@virtualbox>

Hello Johannes,

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

> On Thu, 1 Sep 2016, Jakub Narębski wrote:

Show 16 quoted lines

>> 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