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Postings from April 2000
>ll153-4: Otherwise, the lefter one always wins.
>Cute though it is, I'd rather see something like 'the leftmost of the
>two'.
The problem with that, which I did consider, is that -most is in
the superlative degree, something that cannot occur when merely two
items are being compared. For that, you need the comparative degree.
>l172: octal char (think of a PDP-11);
>Does 'think of a PDP-11' actually help anyone understand this?
>(I appreciate this phrase was not introduced by Tom's patch.)
Sure: if you learned macro assembler and C on a PDP-11, the way
many of us did. :-)
>l179: \u titlecase next char
>Not sure what 'titlecase' means, or why it is more accurate than
>'uppercase', nor why \U was not similarly changed.
Because that doesn't happen there. "titlecase" is a Unicode notion.
(It's somewhat misleading, since it doesn't really understand proper
titlecasing rules in English.) But some scripts (read: charsets)
allegedly distinguish between these. That's why toke.c has
toUPPER_LC_uni for uc(), but toTITLE_LC_uni for ucfirst().
>ll577-580:
> For reasons of security, this construct is normally forbidden if
> the regex involves variable interpolation, unless the perilous C<use
> re 'eval'> pragma has been used (see L<re>), or the variables contain
> results of C<qr//> operator (see L<perlop/"qr/STRING/imosx">).
>I don't think this is correct.
>I _think_ the story is that without C<use re 'eval'>, you cannot combine
>variables and code within a regexp, but that you can put code into a
>qr// regexp (as long as you don't mix in variables to be interpolated),
>and then interpolate the variable containing the evalable qr// pattern
>along with other variables into a new pattern. Thus this is allowed:
> $y = qr/(?{ "code here" })/;
> /$x$y$z/;
>.. but these aren't:
> $x = qr/./; /(?{ "code here" }) $x/;
> $x = qr/(?{ "code here" }) $y/;
>l609: Execute I<code> and interpolate its result as more pattern.
>I think 'as a subpattern' might be more accurate, since you can't
>say, for example, /(??{ "(" }) . (??{ ")" })/.
I believe this is fundamentally broken. I think Ilya simply screwed up.
>ll638-9:
> This is mostly useful as an efficiency hack
> to optimize of what would otherwise be "eternal" matches [...]
>"to optimize what would", "to break out of what would"?
It was supposed to be the former. (Note comparative degree. :-)
>ll695-7:
> Be aware, however, that this pattern currently
> triggers a warning message under the C<use warnings> pragma or B<-w>
> switch saying it C<"matches the null string many times">.
% perl -we '/(a*)*/'
Use of uninitialized value in pattern match (m//) at -e line 1.
% perl -we '/\b*/'
\b* matches null string many times at -e line 1.
Use of uninitialized value in pattern match (m//) at -e line 1.
MRE says interesting things about all this.
>I was unable to find evidence of this in any version of perl I have
>here. I appreciate this sentence was not introduced by Tom's patch.
thanks,
--tom
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