From: Tobias DiPasquale <anany@...>
Date: 2001-08-01T03:11:50+09:00
Subject: [ruby-talk:18904] Re: Digits in method names

Indeed you are correct. Most parsers in use are one-character look-ahead due to
speed constraints. I forgot to mention that. My bad :(

brucedickey wrote:

> > -----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.
> >