如何在 Log::Log4perl 配置文件中使用 Perl 变量？

Question

I would like to use a Perl variable from my script in a Log::Log4perl config file. I read the documentation and found that I can use a subroutine, but I would like to do it a little bit simpler, if possible.

I want to set the filename for my appender:

log4perl.appender.av_std_LOGFILE.filename="whateverfilename.log"

But doing this this way, it is a fixed value.

I have the filename in a variable within my script and would like to use this at runtime:

log4perl.appender.av_std_LOGFILE.filename=\
 sub { return &av_getLogfileName(); }

Where this is the subroutine:

sub av_getLogfileName
{
    return $av_std_LOGFILE;
}

This works, but I would like to avoid the sub inside my script since the return value is very simple.

The documentation says:

Each value starting with the string sub {... is interpreted as Perl code to be executed at the time the application parses the configuration...

So I tried something like this, but it did not work:

log4perl.appender.av_std_LOGFILE.filename=\
    sub { print "$av_std_LOGFILE"; }

Is there a way to get result of the variable without the sub inside my script?

Answer 1

print成功时返回 1，所以

sub { print "$av_std_LOGFILE"; }

返回 1，而不是 的值$av_std_LOGFILE。您还必须完全限定 hooks 中的变量名称，这意味着您必须将$av_std_LOGFILE包设为全局。

将你的钩子更改为：

sub { return $main::av_std_LOGFILE; } # double quotes are unnecessary

并在脚本中设置$av_std_LOGFILE如下（在调用之前Log::Log4perl::init）：

our $av_std_LOGFILE = '/path/to/logfile';

一般来说，您应该避免全局变量，所以我更喜欢使用子例程。