Perl：强制堆栈跟踪“不能调用未定义的方法” [英] Perl: Force stacktrace for "can't call method on undefined"

问题描述

我使用Perl和Catalyst作为Web框架。

I'm using Perl and Catalyst as Web-Framework.

我如何全局强制堆栈跟踪，如果一个例外，如code>无法调用方法XXX在未定义的值... 被抛出？

How can I globally force a stacktrace if an exception like Can't call method "XXX" on an undefined value... is thrown?

假设您的 Controller / Root.pm

use DateTime;

sub test  :Local :Args(0) {
    my ( $self, $c ) = @_;
    my $now = DateTime->now(time_zone=>'local');
    my $tmp = undef;

    my $throwing = $tmp - $now; #this will throw an exception!
    $c->res->body("OK");
}

打开 http：// localhost：3000 / test 抛出当然的例外：

在MyApp :: Controller :: Root-> test中捕获异常'
'subtract_datetime'在
/usr/local/lib/perl/5.10.1/DateTime.pm第1619行1003上的未定义值。

Caught exception in MyApp::Controller::Root->test "Can't call method "subtract_datetime" on an undefined value at /usr/local/lib/perl/5.10.1/DateTime.pm line 1619, line 1003."

堆栈跟踪丢失！

如何在这种情况下强制进行堆栈跟踪？

我想获得（不是真正的输出，只由手工制作）：

I.e. I would like to get (not a real output, only composed by hand):

MyApp::Controller::Root::__ANON__('Can\'t call method "subtract_datetime" on an undefined value at /usr/local/lib/perl/5.10.1/DateTime.pm line 1619, <DATA> line 1003.^J') called at /home/user/MyApp/script/../lib/MyApp/Controller/Root.pm line 114
MyApp::Controller::Root::test('MyApp::Controller::Root=HASH(0x20583b60)', 'MyApp=HASH(0x206e9140)') called at /usr/local/share/perl/5.10.1/Catalyst/Action.pm line 65
Catalyst::Action::execute('Catalyst::Action=HASH(0x20668e88)', 'MyApp::Controller::Root=HASH(0x20583b60)', 'MyApp=HASH(0x206e9140)') called at /usr/local/share/perl/5.10.1/Catalyst.pm line 1687
eval {...} at /usr/local/share/perl/5.10.1/Catalyst.pm line 1687
Catalyst::execute('MyApp=HASH(0x206e9140)', 'MyApp::Controller::Root', 'Catalyst::Action=HASH(0x20668e88)') called at /usr/local/share/perl/5.10.1/Catalyst/Action.pm line 60
[ and the rest of the exception ...]

有了这个我知道确切地说，这个例外是由Root.pm中的第114行引起的。

With this I know exactly that the exception was caused by the line 114 in Root.pm

推荐答案

我不知道它是否在Catalyst内工作，但是通常您可以通过包括CPAN模块来强制堆栈跟踪。 Carp :: Always ，例如通过在程序中的某个地方写入使用Carp :: Always; 或者使用启动perl脚本-MCarp :: Always 开关。

I am not sure if it works within Catalyst, but usually you can force a stacktrace by including the CPAN module Carp::Always, e.g. by writing somewhere in your program use Carp::Always; or starting the perl script with the -MCarp::Always switch.

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