[antlr-interest] philosophy about translation

[Andy Tripp]

Monty Zukowski wrote:

> ...
>
>> > Just for the record I am opposed to the translation you show  here.
>> > That is not at all what I would expect unless it's clear that  those
>> > variables are always constants.
>>
>>
>> Ahh...and therein lies the difference in our approaches. It's not what
>> you'd *expect* because of your background
>> in language tools. But is it what you'd *want* as a customer who wants
>> to replace C code with Java? Answer: customers
>> don't want "JOBOL", and they don't want "Cava". (Although, if they do
>> want C in Java clothes, there's
>> a tool for that: http://ovid.tigris.org/Ephedra/)
>
>
> Note, you missed the fact that it has to be clear that those variables
> are constants.  Obviously, if they are not, then you can't do the
> substitution.

Right.

>
> Also as I was thinking about it, I don't like eliminating the
> variables just because they are constants.  

Right. And thinking about it more, I think I lied, and I'd produce
System.out.println("hello" + " " + "world");
I do, however, attempt to do what real programmers would do.
Like I might see that a single println() call contains a bunch
of constants, all used only once, and so I should combine them.
I don't do that for C to Java, but I do for COBOL, where the nature of
how you declare variables make that a common occurance.

In COBOL, you very often see roughly:
01  MESSAGE
                05 HELLO PIC XXXXX VALUE "HELLO"
                05               PIC X VALUE SPACE
                05 WORLD PIC XXXXXX VALUE "WORLD"
...
WRITE MESSAGE

Here, not only are they constants, but in fact one of them (the space) 
doesn't
even have a name!

> Sometimes programmers do
> things like that to make the code more readable, and crunching it into
> one line again makes it less readable.  Without knowing the intent of
> the programmer I would say it should not do such fancy things as
> variable substitution.  Worse yet, if the string is overridden later,
> or tested against, or things like that, then you've made the code
> harder to maintain by putting the constant everywhere (perhaps
> embedded in other strings).

Yea, this is the sort of thing I struggle with every day.

>
> Monty
>