Re: [perl #116407] SvPVutf8 != SvPVX, and sv_2pvutf8

On Thu, May 09, 2013 at 03:56:49PM +0100, Nicholas Clark wrote:
> This also looks useful. Is there a good way to add (without clutter) the
> possibility that the implication of this is that repeated calls to SvPV() on
> the same scalar might each produce a pointer to a different buffer?
> 
> That has caught out some code before, including in the core.


Is this good enough for yuz?

commit fe02ddb7a070fc75fab3f7c2ed77f31b0dc5fc23
Author:     David Mitchell <davem@iabyn.com>
AuthorDate: Thu May 9 16:57:56 2013 +0100
Commit:     David Mitchell <davem@iabyn.com>
CommitDate: Thu May 9 17:05:15 2013 +0100

    further tweak SvPV() docs
    
    Make it clear that a different pointer may be returned each time.


Affected files ...
    
    M	sv.h

Differences ...

diff --git a/sv.h b/sv.h
index 4bfbf9c..7baef34 100644
--- a/sv.h
+++ b/sv.h
@@ -1490,11 +1490,13 @@ stringified version becoming C<SvPOK>.  Handles 'get' magic.  See also
 C<SvPVx> for a version which guarantees to evaluate sv only once.
 
 Note that there is no guarantee that the return value of C<SvPV()> is
-equal to C<SvPVX(sv)> (or even that C<SvPVX(sv)> contains valid data), due
-to the way that things like overloading and Copy-On-Write are handled.  In
-these cases, the return value may point to a temporary buffer or similar.
-If you absolutely need the SvPVX field to be valid (for example, if you
-intend to write to it), then see L</SvPV_force>.
+equal to C<SvPVX(sv)>, or that C<SvPVX(sv)> contains valid data, or that
+successive calls to C<SvPV(sv)) will return the same pointer value each
+time. This is due to the way that things like overloading and
+Copy-On-Write are handled.  In these cases, the return value may point to
+a temporary buffer or similar.  If you absolutely need the SvPVX field to
+be valid (for example, if you intend to write to it), then see
+L</SvPV_force>.


-- 
"I do not resent criticism, even when, for the sake of emphasis,
it parts for the time with reality".
    -- Winston Churchill, House of Commons, 22nd Jan 1941.

• [perl #116407] SvPVutf8 != SvPVX, and sv_2pvutf8 by bulk88
• Re: [perl #116407] SvPVutf8 != SvPVX, and sv_2pvutf8 by Tony Cook
• Re: [perl #116407] SvPVutf8 != SvPVX, and sv_2pvutf8 by Dave Mitchell
• Re: [perl #116407] SvPVutf8 != SvPVX, and sv_2pvutf8 by Dave Mitchell
• Re: [perl #116407] SvPVutf8 != SvPVX, and sv_2pvutf8 by Nicholas Clark
• Re: [perl #116407] SvPVutf8 != SvPVX, and sv_2pvutf8 by Dave Mitchell
• [perl #116407] SvPVutf8 != SvPVX, and sv_2pvutf8 by bulk88 via RT
• Re: [perl #116407] SvPVutf8 != SvPVX, and sv_2pvutf8 by Dave Mitchell
• Re: [perl #116407] SvPVutf8 != SvPVX, and sv_2pvutf8 by Dave Mitchell
• Re: [perl #116407] SvPVutf8 != SvPVX, and sv_2pvutf8 by Leon Timmermans
• Re: [perl #116407] SvPVutf8 != SvPVX, and sv_2pvutf8 by Dave Mitchell