Checking status of implicit open (diamond operator)

deibyz has asked for the wisdom of the Perl Monks concerning the following question:

Wise monks,

I have some functions that perform inplace edits on files passed as arguments. I set $^I to use <> "magic". They look like that:

sub inplace{
    my @files = @_;
    
    local ($^I, @ARGV) = (".bak", $file); # Now i can use <> 
    
    while(<>){
        # do stuff on $_
        print;
    }
}
[download]

Now, I would like to check if all the files were successfully opened (like in open or die "$!"), but I can't find anything in the documentation that tells me how to do it. Is there anyway to do it without refusing to use $^I and <> "magic"?

Edited: Forgot local

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Re: Checking status of implicit open (diamond operator) by BrowserUk (Patriarch) on Mar 17, 2005 at 12:50 UTC
Set a __WARN__ handler. `>perl -i.bak -e"$SIG{__WARN__}=sub{ warn qq[failed:$ARGV]}; print <>" +fred.dat failed: fred.dat at -e line 1.` [download] Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. Lingua non convalesco, consenesco et abolesco. Rule 1 has a caveat! -- Who broke the cabal?	[reply] [d/l]
Re^2: Checking status of implicit open (diamond operator) by deibyz (Hermit) on Mar 17, 2005 at 14:37 UTC
Thank's a lot for your reply! Was exactly what I need ++ Now I have to make sure I'm not trapping the rest of the warnings, any guidance on where to search for info?	[reply]
Re^3: Checking status of implicit open (diamond operator) by BrowserUk (Patriarch) on Mar 17, 2005 at 14:55 UTC
You're localising `$^I` and `@ARGV`, localise `$SIG{__WARN__}` also: `sub inplace{ my @files = @_; local($^I, @ARGV)=(".bak", $file); # Now i can use <> local $SIG{__WARN__} = sub{ ## Handle open errors here }; while(<>){ local $SIG{__WARN__}; # disable it for loop body # do stuff on $_ print; } }` [download] Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. Lingua non convalesco, consenesco et abolesco. Rule 1 has a caveat! -- Who broke the cabal?	[reply] [d/l] [select]
Re: Checking status of implicit open (diamond operator) by Joost (Canon) on Mar 17, 2005 at 12:51 UTC
AFAIK `while(<>)` already does that. Observe: `> perl -nple1 non-existing Can't open non-existing: No such file or directory. > perl -nple1 unreadable.txt Can't open test.txt: Permission denied.` [download] update: actually, it appears to just skip processing the file (giving the warning), instead of abort, so you still need a SIG{__WARN__} or use warnings FATAL => all to catch it. "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply] [d/l] [select]