Re: warnings under the debugger

Could it be because the debugger evals its input rather than submitting directly to Perl?

Update: ... and notwithstanding the, erm, confident reply below, I can now suggest this demo:

unixhost> # case 1 without eval
unixhost> perl -ew '$foo = { bar => () };'
Name "main::foo" used only once: possible typo at -e line 2.
Odd number of elements in hash assignment at -e line 2.
unixhost>
unixhost> # case 2 - now "protect it" with eval ...
unixhost> perl -ew 'eval "$foo = { bar => () };";'
unixhost>
unixhost> # nothing!
[download]

-M

Free your mind

Comment on Re: warnings under the debugger Download Code

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Re^2: warnings under the debugger by almut (Canon) on Mar 08, 2007 at 16:38 UTC
unixhost> perl -ew* 'eval "$foo = { bar => () };";'* If I use `-we` instead of `-ew`, I do get the warnings with `eval`, too... `$ perl -we 'eval "$foo = { bar => () };";' Name "main::foo" used only once: possible typo at -e line 1. Use of uninitialized value in concatenation (.) or string at -e line 1 +.` [download] (I figure that with `-ew`, the program is just the bareword "w", which is being passed the rest of the commandline as arguments :)	[reply] [d/l] [select]
Re^2: warnings under the debugger by Moron (Curate) on Mar 08, 2007 at 16:55 UTC
Therefore I am still suggesting that an explanation for the symptoms is that, to use Anno's words, the debugger "starts a new interpreter each time ..." ... it reads the keyboard input and uses "string eval" on it instead of submitting it directly to Perl. -M Free your mind	[reply]
Re^3: warnings under the debugger by Anno (Deacon) on Mar 08, 2007 at 21:14 UTC
When I tried it (I don't use the debugger normally), I found that the warning is shown, if warnings are switched on. Here is a (slightly edited) session: `anno@oliva> perl -wd -e '' Loading DB routines from perl5db.pl version 1.28 [...] DB<1> $x = { 1 } Odd number of elements in anonymous hash at (eval 10)[/usr/local/lib/p +erl5/5.8.7/perl5db.pl:628] line 2. [...]` [download] So it seems the debugger has ways of restoring the warning state of the outer interpreter in an `eval`. (Can't be that hard). Why the original poster didn't see the warning remains an open question. Anno	[reply] [d/l] [select]
Re^4: warnings under the debugger by Moron (Curate) on Mar 12, 2007 at 14:14 UTC
Yes, I see your point. I think it's because -w (which you used in your test) makes the debugger eval with warnings as well whereas -Mwarnings (which the OP used instead) loads the warnings pragma as if it were explicitly loaded for the code being debugged while leaving the debugger's own separate interpreter instance unaffected. -M Free your mind	[reply]
Re^2: warnings under the debugger by Anno (Deacon) on Mar 08, 2007 at 16:39 UTC
Well, that's string eval, which starts a new interpreter with warnings switched off to begin with. Technically you are correct, string `eval` has a radical effect on warnings :) What I meant to say is that a warning that is generated inside an `eval` (of any type) will be shown. Warnings are not suppressed by `eval` in a similar way `die` is. `perl -we 'eval "use warnings; $foo = { bar => () };";` [download] will print the warning, even from within `eval`. Anno	[reply] [d/l] [select]
Re^2: warnings under the debugger by Anno (Deacon) on Mar 08, 2007 at 14:40 UTC
`eval` has no effect on warnings. Anno	[reply] [d/l]