>From: Peter Scott [mailto:[EMAIL PROTECTED] >Sent: 22 June 2007 13:25 >To: [EMAIL PROTECTED]; dbi-users@perl.org >Subject: Re: perl pad.c Assertion !((sv)->sv_flags & 0x00010000) failed > >On Thu, 21 Jun 2007 22:33:03 +0100, Tim Bunce wrote: >> On Thu, Jun 21, 2007 at 06:47:11PM +0200, Rafael Garcia-Suarez wrote: >>> On 21/06/07, Steve Hay <[EMAIL PROTECTED]> wrote: >>> >I remember lots of discussion a while ago about constructions like "my >>> >$x = 1 if $y;". I don't remember what the conclusion of it all was, >>> >except that it's probably best avoided. Is that right? >>> >>> Yes, that's right, because that could bypass initialisation of $x if >>> $y is false, leaving the previous value in it, like in state vars. >> >> I thought that issue only related to a "compile-time constant false" >> (such as the one in your example) and not to a runtime expression that >> happened to be false sometimes. >> >> Looking at it another way, are you saying that (ignoring closures) >> subroutine scoped lexicals are not cleared when the subroutine exits, >> but persist (consuming memory) until the subroutine is reentered? > >$ ./perl -wle '$q = shift; sub foo { my $x if $q; print $x // $]; \ > $x = 42 } foo; $q++; foo' 0 >5.009005 >42 > >It looks like it, no? > >-- >Peter Scott
To be fair most of the programming languages I'm familiar with don't guarantee the value of a variable before its first assignment so I guess this is to be expected. The value will likely not be held over between calls but the value will be "unpredictable" on each invocation. Ken. **************************************************************************************************************************************************** This e-mail and any accompanying documents contain confidential information intended for a specific individual which is private and protected by law. If you are not the intended recipient, any disclosure, copying, distribution or other use of this information is strictly prohibited. You are also requested to advise us immediately if you receive information which is not addressed to you. beCogent is Authorised and Regulated by the Financial Services Authority.beCogent Registered Office Address: 75 Aldwych London WC2B 4JF Company Registration Number: 3742876 Place of Registration: London *****************************************************************************************************************************************************
