SVN::错误回调如何识别从中调用它的上下文?

好的,我假设问题是:(a)当发生错误时,您想在某个对象中设置一个标志,然后在所有操作结束时检查该标志;(b)您的错误处理程序(在全局变量中)需要某种方式来知道要接触哪个对象。您可以使用一个闭包来实现这一点,如下所示:

#
# This part is the library that implements error handling a bit like
# SVN::Client
#
sub default_error_handler {
  croak "An error occurred: $_[0]";
}

our $global_error_handler = \&default_error_handler;

sub library_function_that_might_fail {
  &$global_error_handler("Guess what - it failed!");
}

#
# This part is the function that wants to detect an error
#
sub do_lots_of_stuff {
  my $error = undef; # No errors so far!

  local($global_error_handler) = sub { $error = $_[0]; };

  library_function_that_might_fail();
  library_function_that_might_fail();
  library_function_that_might_fail();

  if ($error) {
    print "There was an error: $error\n";
  }
}


#
# Main program
#
do_lots_of_stuff();

关键是,当 do_lots_of_stuff() ,我们将错误处理程序设置为匿名Sub,该Sub继续访问创建它的函数的局部变量,以便它可以修改 $error 表示发生了错误。