From: Alex Young <alex@...>
Date: 2007-10-20T18:56:20+09:00
Subject: Re: Is it always the norm to skip 'return'?

Arlen Christian Mart Cuss wrote:
> On Sat, 2007-10-20 at 09:23 +0900, Pat Maddox wrote:
>> You're doing great up until
>>
>>> but even that is considered bad programming practice (functions should have
>>> only one exit).
>> which is just ridiculous.
> 
> I concur. There's nowhere that says that functions should have just one
> exit - it doesn't necessarily make for bad style, or code noise.
http://www.research.att.com/~bs/JSF-AV-rules.pdf, section 4.13.2, Return 
Types and Values:

"AV Rule 113 (MISRA Rule 82, Revised)
Functions will have a single exit point.
Rationale: Numerous exit points tend to produce functions that are both 
difficult to understand and analyze.
Exception: A single exit is not required if such a structure would 
obscure or otherwise significantly complicate (such as the introduction 
of additional variables) a function�s control logic. Note that the usual 
resource clean-up must be managed at all exit points."

This is from a (heavily referenced) C++ style guide, specifically for 
code written for the Joint Strike Fighter.  I'm no C++ expert, but I'm 
led to believe that having more than one exit point in a function in C++ 
can lead to resource release problems.  As such, it would have a clear, 
practical effect there.  Also, C++ functions tend to be longer (in pure 
LOCs) than Ruby methods, so structural complexity is more of a barrier 
to comprehension.  If you google for "single-entry, single-exit" you'll 
find more references to this style and where it comes from - typically 
high-reliability embedded system design, as far as I can tell.

It's less of a problem in Ruby, I think, mainly because of the 
expressiveness and the presence of GC.

-- 
Alex