Function names and “Clean Code”, part 2

See also: Part 1

Oh, the frustrations of obvious function names that don’t actually help.

LED1_On();
LED1_Off();
...
LED9_On();
LED9_Off();

First, it’s quite obvious that LED1_On() probably turns LED #1 on, and LED1_Off() turns it off. Simple.

But what is LED #1?

For most of my programming career, I have coded this way. You can always tell folks what that LED is in the commands… But then, of course, you don’t always do that everywhere it is used, and then if it is ever changed, all the old comments lie. (Thank you, Clean Code book, for making me fear comments.)

Today, I treat this kind of like how the OS-9 operating system treated devices… There is a device description (the thing that you are trying to access by name) and a device driver (the thing that controls the thing you are actually trying to access). Under OS-9, a hard disk might have been called “/h0” or “/h1”. A disk drive might have been “/d0” or “/d1”. The device drivers may have been some cryptic name with a chip number in it, such as “fd507” or “rb1003”. But that didn’t matter, because the used didn’t have to know and didn’t have to care. “/d0” was probably the main disk drive on any OS-9 system with a disk drive, regardless of what the actual underlying hardware was.

So for coding these days, I tend to write “low level” driver type functions like LED1_On() and LED2_Off(), and then wrap them in some clean code like:

void StatusLEDOn()
{
   LED1_On();
}

void StatusLEDOff()
{
   LED1_Off();
}

That adds a “useless” layer of code, but it keeps things nice and separate. If I see “StatusLEDOn()” in code, I can assume it probably turns on whatever the Status LED is. And if I see that function, I can determine that the Status LED must be LED #1.

And a good optimizer will likely just optimize these “useless” functions away, anyway.

Thanks to that stupid book, now when I see “ReadAI(2)” or “ToggleDO(5)” I just want to dive in and write wrapper functions to make that code look like “GetCurrentTemperature()” or “ToggleStatusLight()”.

I really need to go back and update all my code on GitHub some day…

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