Re^3: Alternative to bytes::length()

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Re^4: Alternative to bytes::length() by ikegami (Patriarch) on Dec 23, 2009 at 02:15 UTC
Actually, simply calling `length` on a scalar with `UTF8=1` adds the magic. `>perl -MDevel::Peek -e"Dump $_=chr(0x2660)x100; length $_; Dump $_" SV = PV(0x2379ec) at 0x1845eec REFCNT = 1 FLAGS = (POK,pPOK,UTF8) PV = 0x184c5ec "..."\0 [UTF8 "..."] CUR = 300 LEN = 304 SV = PVMG(0x18242cc) at 0x1845eec REFCNT = 1 FLAGS = (SMG,POK,pPOK,UTF8) IV = 0 NV = 0 PV = 0x184c5ec "..."\0 [UTF8 "..."] CUR = 300 LEN = 304 MAGIC = 0x1824e64 MG_VIRTUAL = &PL_vtbl_utf8 MG_TYPE = PERL_MAGIC_utf8(w) MG_LEN = 100 <---------- char length` [download] It's a pity that actions such as `chop`, appending a `UTF8=0` string, etc void the count instead of updating it. Note that `$_ eq ''` doesn't add the magic, so not only is it faster, it uses less memory.	[reply] [d/l] [select]
Re^4: Alternative to bytes::length() by creamygoodness (Curate) on Dec 23, 2009 at 02:25 UTC
Looks like you found the caching mechanism. From perlguts: `w PERL_MAGIC_utf8 vtbl_utf8 UTF-8 length+offset cac +he` [download] As for keeping `bytes`... meh, my attachment to the `bytes` pragma extended only to that use case, as the efficiency of `CORE::length()` with `SVf_UTF8` scalars is a bummer. I'm not even going to bother posting to p5p now that my concern has been addressed another way.	[reply] [d/l] [select]