Re^5: Why is "any" slow in this case?

Why do we need $1 to be magic, when it's read-only?

We don't need it to be. As I mentioned, the alternative would be to make make a copy of the matched text on match. The down side is that this would happen even if $1 isn't used. Same goes for all the other vars I mentioned.

if this is about avoiding overhead for optional variables, retrieving it just once on demand would be sufficient.

That's not how magic works. Get magic changes a variable from something that stores a value, to a function that produces the value on demand. You can either store the value in the var, or generate it each time the var is accessed.

Comment on Re^5: Why is "any" slow in this case? Download Code

Replies are listed 'Best First'.
Re^6: Why is "any" slow in this case? by LanX (Saint) on Jul 28, 2025 at 20:33 UTC
OK I always took the word "magic" as term for various "implementation quirks" in Perl and not as a well defined mechanism. Variable::Magic suggests otherwise ... ... learning every day something new. :) Cheers Rolf _{(addicted to the Perl Programming Language :) see Wikisyntax for the Monastery}	[reply]
Re^7: Why is "any" slow in this case? by ikegami (Patriarch) on Jul 29, 2025 at 11:35 UTC
Correct, I'm referring to the magic added by `sv_magic`. `$ perl -MDevel::Peek -e'Dump( $1 )' SV = PVMG(0x561e81adde40) at 0x561e81af86f0 REFCNT = 1 FLAGS = (GMG,SMG) # Has get magic, has set magic IV = 0 NV = 0 PV = 0 MAGIC = 0x561e81b067d0 # Magic's data, incl callbacks MG_VIRTUAL = &PL_vtbl_sv MG_TYPE = PERL_MAGIC_sv(\0) MG_OBJ = 0x561e81af86d8 MG_LEN = 1` [download] Magic is used by most punctuation vars (e.g. `$!`, `$$`, `%ENV`, `%SIG`), `tie`, lvalue operators (specifically `substr`, `vec`, `pos` and `$#a`), `f( $h{ x } )` (to prevent autovivification) and more.	[reply] [d/l] [select]