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Postings from January 2011
Abigail <abigail <at> abigail.be> writes: >>Ah - I do not use the | operator in everyday programming (in fact, I don't >>think I have ever used it) > sysopen $fh, "foo", 0666, O_CREAT | O_EXCL; OK, yes I have done that - but surprisingly, not in my day job for the past few years. Maybe because if something requires locking or atomic access I tend to store it in an RDBMS instead, and rely on File::Temp for tempfiles. >>Surely the expression 0 + $b should not mutate the value >>of $b. I'm surprised this is not considered a bug? > >I'm pretty sure I'd like $b to get a numerical value if I use it in >numeric context. I'd surely like to receive a numerical value when using numeric context. And I'd like $b to be assigned a numerical value if I wrote an assignment. But for just mentioning the expression ($b + 0) to cause an assignment to $b - albeit a subtle one that you don't always notice - seems quite wrong. The expression should return a numerical value but leave $b untouched, IMHO. This oddity leads to an example Readonly changing the semantics of a program: my $b = "abc100"; $a = "abc100"; 0 + $b; $c = $b; $a ++; $c++; print $c; produces '1', whereas use Readonly; Readonly my $b => "abc100"; $a = "abc100"; 0 + $b; $c = $b; $a ++; $c++; print $c; produces 'abc101'. That must count as a bug either in Readonly or in perl. Either $b is modified or it is not. If it is not modified, then marking it readonly should make no difference. If it is modified, then the Readonly version should fail with a run time or compile time error at the point where modification is attempted. -- Ed Avis <eda@waniasset.com> perl -MReadonly -E 'Readonly my $b => "abc100"; $a = "abc100"; 0 + $b; say $a; say $b; $c = $b; $a ++; $c++\ ; say $a; say $c' -- Ed Avis <eda@waniasset.com>Thread Previous | Thread Next