[RFC][Change-Request] Create usefulness in rc.subr etc/rc.conf.d/*.conf namespace.

[Devin Teske]

On May 8, 2011, at 5:23 PM, Jason Hellenthal wrote:

> 
> Devin,
> 
> On Sun, May 08, 2011 at 03:52:06PM -0700, Devin Teske wrote:
>> 
>> I second Jilles all-builtin solution using `for' globbing (no forking external processes or sub-shells).
>> 
>> Slight modification for brevity:
>> 
>> 	for _modular_conf in /etc/rc.conf.d/*.conf; do
>> 		[ -f "$_modular_conf" -a -x "$_modular_conf" ] || continue
>> 		debug "Sourcing $_modular_conf"
>> 		. "$_modular_conf"
>> 	done
>> 
>> Though I still think it ought to be:
>> 
>> 	for _modular_conf in /etc/rc.conf.d/*.conf; do
>> 		[ -f "$_modular_conf" ] || continue
>> 		debug "Sourcing $_modular_conf"
>> 		. "$_modular_conf"
>> 	done
>> 
> 
> Keeping with the examples of the rest of the style of rc.subr and plenty 
> of other shell scripts here. This would be a distortion of the 
> functionality that the original loop is doing and should be avoided.
> 

I've picked up this tid-bit over the years:

1. Since a conditional block causes all code within to be indented...
2. if you have a condition which can cause a continuance within a looping bock...
3. utilizing said conditional early-on can prevent unnecessary indentation in the following lines.

It's kind of moot for such a small example, but if you get to nesting 300+ lines at multiple levels of nesting then it's worth re-evaluating the use of "early continuances".

Here's the basic idea...

	for item in list; do
		: condition to continue
		: what the loop does
	done

opposed to:

	for item in list; do
		if : condition to not continue; then
			: what the loop does
		fi
	done

How about this half-and-half approach (actual code):

	for _modular_conf in /etc/rc.conf.d/*.conf; do
		if [ ! -f "$_modular_conf" ]; then
			continue
		fi
		debug "Sourcing $_modular_conf"
		. "$_modular_conf"
	done

Of course, one's interpretation of the above syntax is conditional on memorizing that "!" is pronounced "not" (just as my previous syntax hinges on memorizing that "||" is pronounced "or"/"else" -- allowing either syntax to be read/interpreted with ease).

Just thought I'd share my experiences. Not everyone develops the same style(9) for every language.
-- 
Devin

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