eval '...'; die "err: $!"

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Re: eval '...'; die "err: $!" by haukex (Archbishop) on Nov 09, 2021 at 18:39 UTC
The correct error variable to check after an eval is $@, not $! - the latter is actually empty in this particular case, but could potentially contain an error caused by a previous operation, leading to misleading results (try `perl -Mstrict -we 'chdir("/foobarquz"); eval q(x=3) or die $!'`). Also note `perl -Mstrict -we 'eval q(x=3); die'` has the same behavior as your second example, the reason is documented in die: If LIST was empty or made an empty string, and `$@` already contains an exception value (typically from a previous `eval`), then that value is reused after appending `"\t...propagated"`.	[reply] [d/l] [select]
Re: eval '...'; die "err: $!" by tybalt89 (Monsignor) on Nov 09, 2021 at 18:38 UTC
Wrong var. `perl -Mstrict -we 'eval q(x=3) or die "err $@"'` [download] Outputs: `err Can't modify constant item in scalar assignment at (eval 1) line 1 +, at EOF Bareword "x" not allowed while "strict subs" in use at (eval 1) line 1 +.` [download]	[reply] [d/l] [select]
Re: eval '...'; die "err: $!" by perlfan (Parson) on Nov 10, 2021 at 11:05 UTC
You might have cribbed that from an idiom, like: `open my $fh, q{<}, $file or die $!` Updated before haukex caught my mistake.	[reply] [d/l]
Re^2: eval '...'; die "err: $!" by haukex (Archbishop) on Nov 10, 2021 at 11:11 UTC
You might have cribbed that from an idiom, like: `open my $fh, q{<}, $file \|\| die $!` That's not an idiom, it's wrong because of incorrect precedence: "open" Best Practices. Also, just in case you're implying otherwise, `eval or die` is a decent approach to work around Bug in eval in pre-5.14. Update: It is uncool to update a node in a way that renders replies confusing or meaningless. Mark your updates. Update 2: Now fixed.	[reply] [d/l] [select]
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