I'm not really clear on the purpose; I think it's not how I would have approached the problem. But I can certainly think of situations where I would use a child init handler.

Why do you ask?

Why do you ask?

So I can frame the question better, and because I can't really think of any other purpose for the hook :)

I think you'll find https://metacpan.org/pod/Plack::Handler::Apache2#STARTUP-FILE interesting, as well as https://metacpan.org/pod/Plack::Component#OBJECT-LIFECYCLE and especially https://metacpan.org/pod/Plack::Builder#INLINE-MIDDLEWARE

So you can create your own init_hook as an anonymous inline Plack::Middleware

builder {
  ...
  enable \&child_init_phase;
  $app;
};
...
sub child_init_phase {
    my( $app ) = @_;
    ...   ## your init stuff here
    $app; ## return app unmodified
}
[download]

Thats your PlackChildInitHandler

Thanks, I had read the Plack::Handler::Apache2 doc but not the others.

I will give this a try, but...it's not clear to me how it is doing anything at child init time, not compile time.

--
A math joke: r = | |csc(θ)|+|sec(θ)| |-| |csc(θ)|-|sec(θ)| |