From: brucedickey <brucedickey@...>
Date: 2001-08-01T02:24:57+09:00
Subject: [ruby-talk:18903] Re: Digits in method names



> -----Original Message-----
> From: Tobias DiPasquale [mailto:anany@ece.villanova.edu]
> Sent: Tuesday, July 31, 2001 11:14 AM
> To: ruby-talk@ruby-lang.org
> Subject: [ruby-talk:18901] Re: Digits in method names
> 
> 
> Read about context-free grammars and the theory of compiler 
> design and you
> will know why. Basically, it's because the interpreter sees a 
> number, and
> thinks that a numeric sequence follows, NOT a method or 
> object instance
> name. Allowing numbers to start method/object names would be 
> a task equal
> to a Turing machine, whereas a compiler/interpreter is a CFG.

Yes, in pure theory -- the theory of certain types of parsers, that is.
However, in practice identifiers are usually limited to a fixed number of
significant characters and therefore it is possible to distinguish a number
from an identifier within that number of characters. Most mainstream parsers
are limited to one character of look-ahead (if any) (are LALR, LL(1), etc),
and that is the reason for the restriction.

> 
> Aleksei Guzev wrote:
> 
> > Why not allow starting method names with digits?
> > This would allow measurement units support. I.e. 10cm == 
> 100mm and much
> > more.
>