Question

我试图理解为什么IO::File似乎无法与use autodie一起使用：

示例＃1 ：使用open测试程序：

#! /usr/bin/env perl
#
use strict;
use warnings;
use feature qw(say);
use autodie;
use IO::File;

open( my $fh, "<", "bogus_file" );
# my $fh = IO::File->new( "bogus_file", "r" );
while ( my $line = $fh->getline )  {
    chomp $line;
    say qq(Line = "$line");
}

这失败了：

Can't open 'bogus_file' for reading: 'No such file or directory' at ./test.pl line 9

看起来autodie正在运作。

示例＃2 ：相同的测试程序，但现在使用IO::File：

#! /usr/bin/env perl
#
use strict;
use warnings;
use feature qw(say);
use autodie;
use IO::File;

# open( my $fh, "<", "bogus_file" );
my $fh = IO::File->new( "bogus_file", "r" );
while ( my $line = $fh->getline )  {
    chomp $line;
    say qq(Line = "$line");
}

这失败了：

Can't call method "getline" on an undefined value at ./test.pl line 11.

看起来autodie没有抓住错误的IO::File->new开放。

然而，据我所知，IO::File->new使用了open。这是IO::File的代码：

sub new {
    my $type = shift;
    my $class = ref($type) || $type || "IO::File";
    @_ >= 0 && @_ <= 3
        or croak "usage: $class->new([FILENAME [,MODE [,PERMS]]])";
    my $fh = $class->SUPER::new();
    if (@_) {
        $fh->open(@_)   # <-- Calls "open" method to open file.
            or return undef;
    }
    $fh;
}

sub open {
    @_ >= 2 && @_ <= 4 or croak 'usage: $fh->open(FILENAME [,MODE [,PERMS]])';
    my ($fh, $file) = @_;
    if (@_ > 2) {
        my ($mode, $perms) = @_[2, 3];
        if ($mode =~ /^\d+$/) {
            defined $perms or $perms = 0666;
            return sysopen($fh, $file, $mode, $perms);
        } elsif ($mode =~ /:/) {
            return open($fh, $mode, $file) if @_ == 3;
            croak 'usage: $fh->open(FILENAME, IOLAYERS)';
        } else {
            #  <--- Just a standard "open" statement...
            return open($fh, IO::Handle::_open_mode_string($mode), $file);
        }
    }
    open($fh, $file);
}

导致autodie无法正常工作的原因是什么？

Answer 1

autodie是词法范围的。因此，它会在您的文件中更改（换行）open，但不会在IO::File内。

Perl IO :: File是否可以与Autodie配合使用？

1 个答案: