Perl包错误处理问题

Question

我有一个名为"SamplePkg"的包。我有另一个脚本使用SamplePkg，创建一个对象并调用一个方法。

package SamplePkg;
use strict;
use DBI;
use Try::Tiny;

my $dbh = DBI_>connect(..., { RaiseError => 1 });
sub new { 
   my $self = {};
   $self->{CODE} = 0;
   bless($self);
   return $self;
}
sub do_something {
  my $self = shift;
  try { 
     my $query = "select myvalue from mytable";
     $sth = $dbh->prepare($query);
     $sth->execute();
  } catch { $self->{CODE} = 100; return; }
$self->{CODE} = 50;
}

The other script

use SamplePkg;

my $object = SamplePkg->new();
$object->do_something();
print "Code is: $object->{CODE}n";

Questions:

• For some reason, the try block doesn't catch the DB error (myvalue is not a valid column name)
• The "return" in the catch block does not return to the calling script
• The output gives the error code as 50

Answer 1

try { ... } catch { ... };

是

try(sub { ... }, catch(sub { ... }));

从捕获异常时调用的子进程返回，而不是从try所在的子进程返回。

你可以用

try {
   my $query = "select myvalue from mytable";
   $sth = $dbh->prepare($query);
   $sth->execute();
   $self->{CODE} = 50;
} catch {
   $self->{CODE} = 100;
};

或者你需要更像

my $success = try {
   my $query = "select myvalue from mytable";
   $sth = $dbh->prepare($query);
   $sth->execute();
   return 1;
} catch {
   return 0;
};
... do stuff ...
$self->{CODE} = $succes ? 50 : 100;