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Postings from April 2000
To: perl5-porters@perl.org
From: Zenin <zenin@bawdycaste.org>
Subject: Re: [ID 20000403.009] uninitialised concatenation???
X-Newsgroups: perl.porters-gw
In-Reply-To: <4.3.0.20000404101328.018e1d30@24.8.96.48> <2104.954859198@chthon>
Organization: Zenin's Rocky Horror Archive
User-Agent: tin/pre-1.4-19990413 ("Endemoniada") (UNIX) (FreeBSD/3.2-STABLE (i386))
In message <2104.954859198@chthon> Tom Christiansen <tchrist@chthon.perl.com> wrote:
>snip<
:>Then we need to either:
:>A) Post in big bold letters someplace that internal optimizations may make
:>the errors they get at runtime a little odd
:>or
:>B) Attach enough hint info to the optree to emit errors correct for the
:>original program text
:>A's easier, B's better but more expensive both in compile time and porter
:>time. If the optimizer gets seriously attacked, though, it might be worth it.
:
: There are many many cases of this that could be "attacked". Essentially,
: what people are suddenly expecting is that the compiler insert complete
: source code information during compilation so that during run time, the
: interpreter can say things. Kind of like cc -g. This is potentially
: prohibitively expensive, though, as you point out. It's not like all cc
: compiles run with -g, and for good reason.
How about adding a -g option to perl to do just that?
: Choice 1: Remove the warning and many others.
I'd prefer not to remove it myself. It's rare except in small
programs that I've used uninitialized values where it wasn't an
indication of a bug in my code someplace.
: Choice 2: Educate the users. This is inevitable. Things just are not
: what they were. This is a compiler. That's what compilers do. Ever
: tried debugging highly optimized code from a DEC compiler? Whew!
Agreed. Every compiler has its quirks. Hell, javac even has a page
(part of the FAQ?) that details nearly every error message and what
it *really* means. Perhaps perl needs something similar?
: Choice 3: Redesign the compiler and interpreter to store and access
: complete source code.
:
: The bigger issue, if you're going to be bloating the optree with full
: source information, is to deal with
: $x + $y
: and not knowing which variable was wicked. It doesn't say
: Undefined value in lexical $x defined at line 23 of Foo.pm
: Undefined value in global $Foo::y at line 23 of Foo.pm
Which would be nice, at least via a switch (-g or something).
Probably too much work for the result however. I'd prefer to see
threads happier then warning messages, for instance.
--
-Zenin (zenin@archive.rhps.org) "Hey, are you one of those Linux coders?"
"Nyet. Linux coder in next office."
"Good man. Ignore the screams."
--www.userfriendly.org