Re^3: Question on SV internals

$s = '20 ducks';;
Dump $s;;
SV = PV(0x18aec0) at 0xa5b48
  REFCNT = 1
  FLAGS = (POK,pPOK)
  PV = 0x40cad18 "20 ducks"\0
  CUR = 8
  LEN = 16
[download]

Length = 16. Now use it in a numeric constant.

$s += 1;;
Argument "20 ducks" isn't numeric in addition (+) at (eval 13) line 1,
+ <STDIN> line 4.

Dump $s;;
SV = PVNV(0x40b1eb8) at 0xa5b48
  REFCNT = 1
  FLAGS = (NOK,pNOK)
  IV = 20
  NV = 21
  PV = 0x40cad18 "20 ducks"\0
  CUR = 8
  LEN = 16
[download]

Hm. Length still 16, but we gained an IV = 20 and an NV = 21; so we gained 12 or 16 bytes.

Oh, and the PV no longer reflects the value of the scalar, so when you use it in a string context, a conversion has to happen!

print $s;;
21

Dump $s;;
SV = PVNV(0x40b1eb8) at 0xa5b48
  REFCNT = 1
  FLAGS = (NOK,POK,pNOK,pPOK)
  IV = 20
  NV = 21
  PV = 0x40d3068 "21"\0
  CUR = 2
  LEN = 40
[download]

Which modifies the PV and oops, it grew to 40 bytes in the process.

And I don't care how you try to weasel out of it, the evidence is right there for those that care to look. So don't bother.

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

Comment on Re^3: Question on SV internals Select or Download Code

Replies are listed 'Best First'.
Re^4: Question on SV internals by ikegami (Patriarch) on May 08, 2011 at 16:47 UTC
Now use it in a numeric constant. $s += 1; `$s += 1` does more than "use it in a numeric context". Update: Furthermore, even though you went outside the scope of the question, the scalar still has a numerical value throughout. `FLAGS = (NOK,pNOK)` `FLAGS = (NOK,POK,pNOK,pPOK)` There is no such terminating condition.	[reply] [d/l] [select]
Re^5: Question on SV internals by BrowserUk (Patriarch) on May 08, 2011 at 19:09 UTC
does more than "use it in a numeric context". And of course, that could never happen in a real program. Take your blinkers off. Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply]
Re^6: Question on SV internals by ikegami (Patriarch) on May 08, 2011 at 23:53 UTC
So much misdirection! Are you still claiming the caching only lasts "until you next use it in a string context."? Why don't you show an example of this happening if so?	[reply]