D's hidden function calls getting crazier.

[Atila Neves]

On Friday, 27 October 2023 at 13:37:14 UTC, Hors wrote:
> On Friday, 27 October 2023 at 12:53:32 UTC, duckchess wrote:
>> On Friday, 27 October 2023 at 12:46:37 UTC, Hors wrote:
>>> On Friday, 27 October 2023 at 12:40:39 UTC, duckchess wrote:
>>>> On Friday, 27 October 2023 at 12:38:10 UTC, Hors wrote:
>>>>> [...]
>>>>
>>>> why do you need to know if it is a function call?
>>>
>>> Because it kills D's "fast", you may think you just accessing 
>>> a normal variable but in fact you just calling a lot 
>>> functions, it can hurt performance. Also for years, obj.val 
>>> means a variable amd obj.m() means a function. There is no 
>>> good reason to change that
>>
>> if they can get inlined, they are, so it doesn't really change 
>> anything.
>>
>> also there absolutely is a good reason for this.
>>
>> if you have code
>> ```d
>> struct Foo {
>>  int x = 5;
>> }
>>
>> Foo foo;
>> writeln(foo.x);
>> ```
>>
>> but later realize that you need to have x be a function for 
>> any reason, then you don't have to update your sourcecode 
>> everywhere. like this:
>>
>> ```d
>> struct Foo {
>> int _x;
>>  int x( = 5) { assert(_x > 0); return _x;}
>> }
>>
>> Foo foo;
>> writeln(foo.x);
>> ```
>
> It can be useful in some rare cases.

Either the code isn't being used, or refactoring is common. One 
of my slides at DConf 2023 was literally an extended version of 
"don't use parens for function calls", the reasoning being it 
hurts refactoring.

I'd go so far as to say that these days refactoring is orders of 
magnitude more likely to happen than optimising.

I think the answer to "how can I know if it's a function call" is 
"you shouldn't care unless a profiler told you so". Especially 
since reading data isn't necessarily free either (cache lines).


  But sometimes it does more
> harm than good, like string operations
> ```
> str.toLower
> ```
> calls toLower function which makes a new string every time you 
> use it. So it's incorrect to tell everything can be solved with 
> inline functions