#define SvANY(sv) (sv)->sv_any
#define SvIVX(sv) ((XPVIV*) SvANY(sv))->xiv_iv
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I am just interested to use Perl's data structure for storage.

Then use a string as a C array like BrowserUk suggested, with the following changes:

• You want one of pack 'j' (IV), pack 'J' (UV), pack 'i' (I32) or pack 'I' (U32). It's not constant to which of those 'V' refers.
• Using SvPVX instead of SvPVbyte makes needless assumptions.

Using SvPVX instead of SvPVbyte makes needless assumptions.

I'm sorry to have to start this all over again, but you are wrong. And here is why you are wrong.

The only thing that it makes sense to pass to a routine expecting a scalar containing a string of packed integers, is exactly that.

• An SV without a PV won't cut it. It'll trap.
• An SV containing just an IV, UV, or NV won't cut it

  Even if it was forced to a PV, because treat that as a C array I'll get garbage.

• An SV containing a PV that is UTF8=1 won't cut it.

  If it is downgraded to bytes and then I address it as a C array of ints, I'll get garbage.

• An SV with magic attached won't cut it.

  Treat it as a C int array and I'll get garbage.

The only useful behaviour of those, is the trap. Because it tells me that I haven't passed a packed scalar. Immediately, and unambiguously.

If however, I call SvPVbyte, it won't prevent me from getting a trap if I pass an SV without a PV. But it will turn all the other cases into a piece of memory that there will be no way to discern was not a packed scalar of integers until I start getting garbage results.

And it could take me a long time to trace the source of that garbage back to the error.

The only assumption using SvPVX makes, is that I have passed a properly packed array. And if I haven't, it traps immediately, which tells me exactly where the problem lies.

In other words, the only assumption it makes, is that I know what I'm doing-- and immediately tells me, in no uncertain terms, if I do not.

And that's an invaluable behaviour in any piece of software!

I do not expect you to agree, nor want you to respond.

---

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.

"I'd rather go naked than blow up my ass"

You sure put a lot of effort avoiding what surely has an O(1) cost of microseconds before a costly O(N) operation (according to the OP).

And if you have a library already allocating the memory, you can even reuse it if you use the string approach. Create a reference to a blessed scalar, assign to the scalar's PV the block of memory you got from the library, and set its SvLEN to zero so Perl won't try to free it. You can free it properly from your destructor (thus the reason for blessing).