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Postings from September 2016
On Thu, Sep 15, 2016 at 11:10 AM, Abigail <abigail@abigail.be> wrote: > > Why does use bigint; 1; warn in void context? > [snip] > However, under "use bigint", what looks like a literal 1 to the reader > no longer looks like a plain literal to perl. It's an overloaded > Math::BigInt object. It's no longer a literal, and perl doesn't know > whether fechting the value has any side effects or not. So, it won't > warn. Um, that's just the thing – it does warn: $ perl -we 'use bigint; 1' Useless use of a constant (1) in void context at -e line 1. $ Compare: $ perl -we '1;' -e '2;' -e 'use bigint; 1;' -e2 Useless use of a constant (2) in void context at -e line 2. Useless use of a constant (1) in void context at -e line 3. Useless use of a constant (2) in void context at -e line 4. $ The missing warning from the first literal is, as you said, the special case for 0 and 1. The warning from the penultimate literal shows that the special case for 0 and 1 does not apply when the literals are overloaded. Moreover, the warning from either of the last two literals also shows that perl indeed warns, even if might not "know whether fetching the value has any side effect or not". I'm not saying perl is doing the wrong thing in general to warn for overloaded literals in void context – I'll leave that for you guys, just noting that it does – but as long as I'm writing, I'd say it would be _nice_ if at least the special case (the lack of warning for 0 and 1 in void context) could be retained also when literals are overloaded. Not that I'm expecting it to be easy though. EirikThread Previous