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Postings from October 2016
On Oct 22, 2016, at 4:16 AM, pali@cpan.org wrote:
> On Monday 17 October 2016 23:31:31 pali@cpan.org wrote:
>
> Encode::_utf8_on(sv)
>
>> @@ -972,12 +982,11 @@ SV * sv
>> CODE:
>> {
>> if (SvPOK(sv)) {
>> - SV *rsv = newSViv(SvUTF8(sv));
>> - RETVAL = rsv;
>> - if (SvIsCOW(sv)) sv_force_normal(sv);
>> - SvUTF8_on(sv);
>> + if (SvTHINKFIRST(sv)) sv_force_normal(sv);
>> + RETVAL = newSViv(SvUTF8(sv));
>> + SvUTF8_on(sv);
>> } else {
>> - RETVAL = &PL_sv_undef;
>> + RETVAL = &PL_sv_undef;
>> }
>> }
>> OUTPUT:
>
> Encode::_utf8_off(sv)
>
>> @@ -989,12 +998,11 @@ SV * sv
>> CODE:
>> {
>> if (SvPOK(sv)) {
>> - SV *rsv = newSViv(SvUTF8(sv));
>> - RETVAL = rsv;
>> - if (SvIsCOW(sv)) sv_force_normal(sv);
>> - SvUTF8_off(sv);
>> + if (SvTHINKFIRST(sv)) sv_force_normal(sv);
>> + RETVAL = newSViv(SvUTF8(sv));
>> + SvUTF8_off(sv);
>> } else {
>> - RETVAL = &PL_sv_undef;
>> + RETVAL = &PL_sv_undef;
>> }
>> }
>> OUTPUT:
>
> I'm not sure if these two functions shouldn't call also SvGETMAGIC(sv)
> before SvPOK(sv) and also SvSETMAGIC(sv) after SvUTF8_off/on(sv) calls.
It depends on how they are intended to be used. These are low-level functions for tinkering with the internal encoding of a string (certainly not for general use; in fact, I would argue that their main purpose is to work around bugs in XS code that does not handle utf8 properly).
I am not sure it makes sense to use these on tied variables; after all, the user has to know what it is in the SV to begin with for any use of Encode::_utf8_off to make sense, but a FETCH call (SvGETMAGIC) might actually change whether the string is flagged as utf8.
That said, if someone does it on $/ then I would expect it just to work, so SvGETMAGIC/SvSETMAGIC seem appropriate.
It may be worth adding a caveat to the documentation that they do not make much sense on tied variables, unless you think that the existing caveats are sufficient.
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