perlguts doesn't cover the writing of strings as fully as it does reading. I went through the same confusion -- earlier versions of one of my XS distros, Sort::External, performed unnecessary copy operations before I figured it out.

Spelunking sv.h and sv.c in the Perl source can be very helpful.

--
Marvin Humphrey
Rectangular Research ― http://www.rectangular.com

In reply to Re^4: XS efficient copy by creamygoodness
in thread XS efficient copy by TheDauthi

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