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Postings from October 2013
On Mon, Sep 23, 2013 at 06:59:09AM +0000, Ed Avis wrote:
> In general I suggest that opening a filehandle giving a reference to a
> reference doesn't make any sense, and surely didn't do anything useful
> even before the change identified. It would be better to make it throw
> an exception.
The other approach is to treat it similarly to how other non-string vars
are treated when used as strings, e.g. $x = \1; $x .= 2, which sets
$x to "SCALAR(0x11fd5b0)2".
> Similarly I suggest that open $fh, '<', \undef should also throw.
The test suite for PerlIO::scalar already explicitly expects undef
to behave like an empty string *without* generating any warnings.
I've pushed the following, which fixes the original bug report by going
down the stringifying route.
commit 552908b17471877454d99aa32f7ac5c29ea2efbb
Author: David Mitchell <davem@iabyn.com>
AuthorDate: Thu Oct 17 15:35:14 2013 +0100
Commit: David Mitchell <davem@iabyn.com>
CommitDate: Thu Oct 17 15:46:05 2013 +0100
PerlIO::scalar: stringify refs
If $s in
open my $fh, "<", \$s
or similar is a ref, then
stringify that ref: i.e. convert it from a ref into the string
"SCALAR(0x....)" or whatever.
This fixes
RT #119529 Filehandle opened from ref to ref hangs on reading
which in this case was looping forever, since it kept thinking that
the var was a string ("SCALAR.."), but whose length was 0.
I haven't gone for a complete "always force var into a string" approach,
since PerlIO::scalar has quite a tolerance for "bad" vars; e.g.
it won't warn if $var is undef or a read-only constant number etc;
and it already normalises under some circumstances and not others.
So I've just increased the cases somewhat where it normalises.
Also, I didn't look to closely at the code that was looping (or to put it
another way, I looked at it but didn't understand it), so it could
conceivably still behave badly on some other strange type of variable that
manages to avoid getting normalised.
--
"But Sidley Park is already a picture, and a most amiable picture too.
The slopes are green and gentle. The trees are companionably grouped at
intervals that show them to advantage. The rill is a serpentine ribbon
unwound from the lake peaceably contained by meadows on which the right
amount of sheep are tastefully arranged." -- Lady Croom, "Arcadia"
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