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Re^5: looking for feedback on my first script

by Anonymous Monk
on Jan 09, 2021 at 20:01 UTC ( #11126673=note: print w/replies, xml ) Need Help??


in reply to Re^4: looking for feedback on my first script
in thread looking for feedback on my first script

In Perl, if printf() fails, a fatal error will be thrown long before it returns to the caller.

wrong

I've never checked the return value of sprintf.

then stop talking and read sprintf

  • Comment on Re^5: looking for feedback on my first script

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Re^6: looking for feedback on my first script
by Marshall (Canon) on Jan 09, 2021 at 22:21 UTC
    I disagree about printf() errors.
    With normal file operations, what I said is true. It is almost impossible for a print or printf to "fail" once a local Hard Disk file handle is open. One way would be "File system full", but in that case, a fatal exception is thrown - the calling program won't see that.

    I did make a mistake in interpreting the exact situation. I would have written: return sprintf "..." because I favor explicit return statements.

      In Perl, if printf() fails, a fatal error will be thrown long before it returns to the caller.
      I disagree about printf() errors. With normal file operations, what I said is true. It is almost impossible for a print or printf to "fail" once a local Hard Disk file handle is open. One way would be "File system full", but in that case, a fatal exception is thrown - the calling program won't see that.

      Test before posting. Confidently making incorrect statements doesn't help anyone.

      #!/usr/bin/env perl use warnings; use strict; my $file = $^O eq 'MSWin32' ? "P:\\foo" : '/tmp/foo/bar'; open my $fh, '>', $file or die "$file: $!"; my $data = "\0" x 2_000_000; print "Writing ", length $data, " bytes to $file\n"; printf $fh "%s", $data or warn "printf: $!"; close $fh or warn "close: $!"; print "Still not fatal\n"; __END__ Windows: Install https://www.ltr-data.se/opencode.html/#ImDisk As Administrator: > imdisk -a -t vm -m P: -s 1M -p "/fs:fat /q /y" > perl write.pl Writing 2000000 bytes to P:\foo printf: No space left on device at write.pl line 9. close: No space left on device at write.pl line 10. Still not fatal > imdisk -D -m P: Linux: $ mkdir -vp /tmp/foo $ sudo mount -t tmpfs -o size=1M,uid=`id -u` tmpfs /tmp/foo $ perl write.pl Writing 2000000 bytes to /tmp/foo/bar printf: No space left on device at write.pl line 9. close: No space left on device at write.pl line 10. Still not fatal $ sudo umount /tmp/foo
      I disagree about printf() errors.

      It was all about sprintf, not printf. Different cases and conditions (memory exhausted vs. disk full etc, NFS conditions and such).

      perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'
        I think this was about return values from a subroutine.

        I prefer explicit return statements except in the case of Perl sort sub routines.
        There are Monks who will disagree with this style.
        So be it.

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