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Postings from August 2023
While we've been looking at tidying up a few things around join() and respecting concat overload, we encountered a weird case. Code such as join "sep", $x, $y, $z will call OP_JOIN on the given input list and thus (at least under our fixes) will do things like using overload magic if it exists. But when there is a single item in the "list", code such as join "sep", $x will bypass it. This does not get compiled into an OP_JOIN but instead directly becomes an OP_STRINGIFY - an opcode that exists in core perl but doesn't have convenient syntax for it. OP_STRINGIFY directly squashes a value down to a plain perl string, removing any overload/magic/etc.. that might be on it. This seems perhaps surprising. Similarly, in qq() strings, code such as: "$x$y" will invoke concat magic between $x and $y and return the result of that even if it is not a plain string, but code such as: "$x" will directly invoke OP_STRINGIFY on the value, squashing it down to a plain string and removing the magic. We feel that these are weird cornercases that ideally should behave in a more flexible, predictable and consistent manner. It suggests that it would be nice to have a real builtin function to request that a value get squashed down to a plain string - by invoking the '""' overload if necessary. There's already a core OP_STRINGIFY to invoke here, so it seems simple enough to wrap it as a new builtin - builtin::stringify. If perl provided such a stringify function, then in the presence of the "please make join respect overloading" flag that one-argument specialcase can be removed, as now that special behaviour is no longer required. And while we're there, it would seem useful to have a similar one to squash a value down to a plain number, by invoking the '0+' overload if necessary. There isn't even valid perl syntax for doing this right now - hacks such as adding zero really just invoke the '+' overload and thus may still yield an overloaded or magic value. It'd be nice to have a builtin::numify for this purpose. Shall I write up a PPC document on adding these two? * No don't do that at all * Write a full PPC * Just proceed directly to the PR and implement them already! -- Paul "LeoNerd" Evans leonerd@leonerd.org.uk | https://metacpan.org/author/PEVANS http://www.leonerd.org.uk/ | https://www.tindie.com/stores/leonerd/Thread Next