OpenEuphoria

Re: A question about certain language features

• Posted by Derek Parnell <ddparnell at bigpond.com> Mar 21, 2002
• 636 views

Chris,
I see we are thinking alike here. I suggested the '$' symbol because that is
often used in regular expression syntax to mean the end-of something. The
symbol '0' could also be a coding mistake, but I would think a rare one (eg.
I miskeyed the '9'). Also, it doesn't seem to be associated with "end-of",
except maybe a count-down by NASA.

   a = foo[2..0] -- is what I keyed,
   a = foo[2..9] -- but this is what I meant.
-------
Derek


----- Original Message -----
From: <bensler at mail.com>
To: "EUforum" <EUforum at topica.com>
Sent: Friday, March 22, 2002 8:00 AM
Subject: RE: A question about certain language features


>
> Your syntax, and the form that I am suggesting are virtually identical.
> The difference is in readability, and ease of implementation.
> Compare:
> foo[1..]   == foo[1..length(foo)]
> foo[1..-1] == foo[1..length(foo)-1]
>
> foo[1..0]  == foo[1..length(foo)]
> foo[1..0-1]== foo[1..length(foo)-1]
>
> Your implementation requires 2 checks for substitution.
> My suggestion is to simply subtitute the literal '0' with length(foo)
>
> foo[1..] could just be a typo.
> foo[1..0] is defined explicity.
>
> Yes, my example could be a typo also, but not as likely to happen.
>
> foo[1..-1] the negative could be fairly easily missed.
> foo[1..0-1] knowing that the literal '0' is always substituted with
> length(foo), it's easy to see the intention.
>
>
> To summarize, your implementation adds two new rules, whereas my
> suggestion only adds one.
> The concepts are identical, but the representation is different.
>
>
> Chris
>
> kbochert at ix.netcom.com wrote:
> > -------Phoenix-Boundary-07081998-
> > Content-type: text/plain; charset=ISO-8859-1
> > Content-transfer-encoding: 8bit
> >
> > You wrote on 3/21/02 10:54:37 AM:
> >
> > >Karl,
> > >
> > >   Consider this syntax for shorthand slicing. Your current syntax sort
> > >of defeats the sequence bounds checking.
> > >
> > >seq[1..0] -- seq[1..length(seq)]
> > >seq[1..0-1] -- seq[1..length(seq)-1]
> > >
> > >seq[1..1-1] -- {} (reverse slice)
> > >seq[1..-1] -- index [-1] out of bounds
> > >
> > >integer index   index=0
> > >seq[1..index] -- {} (reverse slice)
> > >
> > >'O' is explicit, it cannot be implied. If it is, the original EU rules
> > >apply.
> > >
> > >I haven't thouroughly looked. Does your shorthand work if it's implied
> > >with a variable?
> > >
> > >
> > >Chris
> >
> > I handle 'foo[2..]' by expanding it textually. I think of it
> > as a macro.
> >
> > when I see the '..' followed by a ']' or '-', I insert the text
> > 'length(foo)' directly into the input stream. (Having previously
> > saved the 'foo').
> > 'foo[2..]' causes the interpreter to actually see 'foo[2..length(foo)]'
> > and 'foo[2..-(a*b)]' is seen as 'foo[2..length(foo)-(a*b)]'
> >
> >
> > As a result, all the normal Euphoria processing is left intact.
> >
> > Thanks for the link
> > Karl Bochert
> >
> >
> > -------Phoenix-Boundary-07081998---
> >
>
>
>
>