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From: Eric Sosman <esosman@comcast-dot-net.invalid>
Newsgroups: comp.lang.java.programmer
Subject: Re: Java blunders
Date: Sun, 27 Jul 2014 18:10:42 -0400
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On 7/27/2014 5:18 PM, Martin Gregorie wrote:
> On Sun, 27 Jul 2014 14:46:05 -0400, Eric Sosman wrote:
>
>> On 7/27/2014 2:28 PM, Martin Gregorie wrote:
>>> On Sun, 27 Jul 2014 10:13:16 -0700, Roedy Green wrote:
>>>
>>>> On Sat, 26 Jul 2014 20:11:24 +0000 (UTC), Martin Gregorie
>>>> <martin@address-in-sig.invalid> wrote, quoted or indirectly quoted
>>>> someone who said :
>>>>
>>>>> Perl and PHP use . as the string concatenation operator. It seems as
>>>>> good as any to me:
>>>>
>>>> I wonder if . would conflict with its use in qualification.
>>>>
>>> That's possible. [...]
>>
>>       Yes: An example was offered upthread.  Expanding on it:
>>
>> 	class Clown {
>> 	    static String clownName = "Bozo";
>> 	    static {
>> 	        System.out.println(clownName.equals("Bozo"));
>> 	    }
>> 	}
>>
>> What output appears when the class is initialized: "true" or
>> "Bozofalse"?
>
> "False", somewhat obviously, though I don't see what this example has to
> do with qualififiers, especially given that some compilers understand
> context-sensitive grammar. In any case, I didn't think this was intended
> as example code as it looks more like a thinly disguised insult than
> anything else.

     It wasn't intended as an insult, disguised or in plain view.  It
was intended to illustrate an ambiguity in the proposed syntax.

     If the `.' were to replace `+' as the string concatenation operator,
then the expression `clownName.equals("Bozo")' would be ambiguous:  It
could mean what we now denote as `clownName.equals("Bozo"), that is,
as "Invoke the equals() method of the `clownName' string, passing
"Bozo" as the argument."  The output would be "true".

     But if `.' could also be string concatenation, then the expression
might equally well mean what we now write as `clownName+equals("Bozo")',
that is, "Invoke the equals method of `this' passing "Bozo" as the
argument, convert its true or false result to a String, and concatenate
that String to `clownName'."  The output would be "Bozofalse".

     All non-void String methods accepting a single suitable argument
would suffer the same ambiguity.  A JavaPrime (Sumatra?) language could
of course adopt rules to resolve the ambiguity -- but would such a
suite of rules actually *reduce* the confusion supposedly caused by
the use of `+'?  C'mon, seriously?

     Cure worse than disease, I think.

-- 
esosman@comcast-dot-net.invalid