From: Brian Candler <b.candler@...>
Date: 2010-11-25T00:15:28+09:00
Subject: Re: Ruby 1.8 vs 1.9

Michael Fellinger wrote in post #963539:
>> from the environment, unless you explicitly code against that. This
>> means the same program with the same data may work on your machine, but
>> crash on someone else's.
>
> And that's why I use and love 1.9.
> The obvious thing isn't so obvious if you actually care about
> encodings, and if you are mindful about what comes from where, it's
> actually helpful to find otherwise hidden issues.

Y'know, I wouldn't mind so much if it *always* raised an exception.

For example, say I have s1 tagged UTF-8 and s2 tagged ISO-8859-1. If 
"s1+s2" always raised an exception, it would be easy to find, and easy 
to fix.

However the 'compatibility' rules mean that this is data-sensitive. In 
many cases s1+s2 will work, if either s1 contains non-ASCII characters 
but s2 doesn't, or vice-versa. It's really hard to get test coverage of 
all the possible cases - rcov won't help you - or you just cross your 
fingers and hope.

You also need test coverage for cases where the input data is invalid 
for the given encoding. In fact s1+s2 won't raise an exception in that 
case, nor will s1[i], but s1 =~ /./ will.

> I hear nobody complain that 1 / 0 raises but 1.0 / 0.0 gives Infinity,

Well, IEEE floating point is a well-established standard that has been 
around for donkeys years, so I think it's reasonable to follow it.

And yes, if I see code like "c = a / b", I do think to myself "what if b 
is zero?" It's easy to decide if it's expected, and whether I need to do 
something other than the default behaviour. Then I move onto the next 
line.

For "s3 = s1 + s2" in 1.9 I need to think to myself: "what if s1 has a 
different encoding to s2, and s1 is not empty or s2 is not empty and 
s1's encoding is not ASCII-compatible or s2's encoding is not 
ASCII-compatible or s1 contains non-ASCII characters or s2 contains 
non-ASCII characters? And what does that give as the encoding for s3 in 
all those possible cases?" And then I have to carry the possible 
encodings for s3 forward to the next point where it is used.

-- 
Posted via http://www.ruby-forum.com/.