On Fri, Nov 15, 2002 at 11:50:52PM +0200, [EMAIL PROTECTED] wrote:
> Michael Lazzaro writes:
> > Let's summarize some of the string-to-num issues:
> >
> > my int $i = literal "0xff"; # 255
> >
> >
> > (3) -- We want to be able to parse a string as a number using a very
> > _specific_ rule; for example, if a user is expected to enter a value in
> > a specific format, like octal "755" or hex "FF", we want to "know" what
> > we're expecting. That implies there may be functions for each common
> > format:
> >
> > my int $i = sci "1e33";
> > my int $i = hex "00ff";
> >
>
> the default behaiviour of "literal" should be same as perl parsing of
> literals. but sub literal can have additional parameters .
Could we come up with a name other than "literal"? This function's
job is to take a string (which may be a literal, user input, or
whatever), and turns it into a number--the human-expected version of
that number, not necessarily the result you would get if you simply
numified the string.
How about "to_num"? Or even just "num"?
> also it seems that there sould be symmetry ( as was declared ) between
> types and type - casting functions
>
> so , probably "literal" should be called "num" or "int" or "uint16" ,
> depending on WYW . or the casting may be let to happen in two stages
> : string -> num -> specific num type ,e.g. uint16
How about if we got adverbial on the problem:
my $str = "0xff";
my $i = num $str;
my $i = num $str : uint16;
my $i = num "1.0_731e3" : float;
my $i = num "1.0_898_798_798_794e7" : double;
And this makes an interesting corner case:
my $i = num "10_000" : byte; # value too large for 1 byte
I can see two ways to handle this--we can have a compile-time warning,
or we could store it to the smallest type that will hold the value and
issue a warning.
> > (4) -- We want to be able to output numbers to strings according to
> > specific formatting rules. One way to do this (aside from using
> > sprintf) is to use sprintf-style formatting strings, perhaps as
> > properties to tie them to individual instances:
> >
> > my int $i = literal "0xff" but as_string('%02x');
Actually, this would be a good reason to have a function called
"literal" -- if it went both ways. So, I could do this:
print literal(200+55):hex; # == print "0xff";
print literal("0xff)); # == print 255;
--Dks
