> Folks,
>
> I've run into a couple of issues with use and was hoping someone could
> help me come up with a solution.
>
> First, I use a specific module in a work environment to set some global
> variables. I want to re-use my code in another environment which doesn't
> have the specific configuration module. I don't want to have to keep two
> separate copies of the code. What I currently use in the work
> environment is of the format:
>
> use lib '/path/to/work/modules';
> use Prefs;
>
> my $config = Prefs->new();
> my $param1 = $config->get("PARAM1");
>
> I'd like to something of the format:
>
> my $param1;
> if (-f '/path/to/work/modules/Prefs.pm') {
> use lib '/path/to/work/modules';
> use Prefs;
>
> my $config = Prefs->new();
> $param1 = $config->get("PARAM1");
> }
> else {
> $param1 = "default value here";
> }
>
> Is something like this possible?
>
perldoc -f eval (2nd form)
Generally you use 'eval' to wrap a segment of code that can die, then
just catch the error and set your default when an error occurs. So in
this case if the module isn't available, can't be loaded (think syntax
error in it), or causes some other error, then the failure will be
caught and you can move on gracefully.
If the examples in the doc aren't sufficient, come back and someone will
provide a good example.
> Also, some of the config-style modules I use store their configuration
> values with the module itself. Using the above example Prefs.pm, the
> function $config->get("PARAM1") might look like:
>
> my $self = shift;
> my $val = shift;
> return $self->{DATA}{$val};
>
> I have code which runs daemonized (using Proc::Daemon) that begins by
> using the Prefs config module. It's quite possible that the parameters
> in the Prefs config module get modified. I may need my daemonized code
> to "refresh" its copy of the Prefs config module to pull in the new
> parameters. Can this be done, or do I have to stop the daemon and
> restart it?
>
> Thanks all!
> - Ed
>
perldoc -f do
There is an example of this very thing in that doc. In the case of your
daemon, usually you would set up a signal handler, catch the signal
(usually HUP) and re-init the config information when that signal is
received.
perldoc perlipc (for more about signal handling)
There is excellent information about daemons in the Network Programming
with Perl book, I highly recommend it if you have the resources and will
be writing code of this nature.
http://danconia.org
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