Evening everyone,

On 06/11/11 17:22, Terence Parr wrote:
> Hi, Sam Harwell and I are talking about the file extension for new ANTLR 4. 
> We think it makes good sense to use .g4 to distinguish the new grammars. 
> They're mostly compatible except that there is no need for syntactic 
> predicates and .g4 allows immediate left recursion. I think it will reduce 
> confusion about what version of ANTLR is necessary to compile a grammar.

I'm pretty new to this ANTLR stuff, and to compilers/translators in 
general, so be gentle with me. ;-)

Why does the file need to have a specific extension at all? I only just 
found out recently that Java classes have to live in a file with the 
same name as the class. Why?

I can write a C++ class called Barney in a file called fred.cpp or 
fred.cxx or fred.c or fred if I like, the compiler and/or make seem 
quite happy with that.

Maybe there is a good reason, Java perhaps? But I fell over at the first 
hurdle trying out the examples in the two books, I decided I didn't like 
a rule called 'r' and a grammar called 'g' and renamed everything, then 
saved in a filename of my choice. Boy did ANTLRWorks whinge at that - so 
I get my telling off, and had to rename the file. After that, fine. But 
I just don't see why it absolutely must be named like this?

Having said that, if *.g4 is required for version 4, then I can live 
with it - I'd like the system to be extension agnostic though - but I'm 
only a tiny little non-essential cog, so I'm happy to be overruled.

Thanks, however, for the ANTLR and ANTLRWorks system. I think I like it 
much better than Flex/Bison. Can you mention those on this list? ;-)


Cheers,
Norm.

-- 
Norman Dunbar
Dunbar IT Consultants Ltd

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