TL;DR

I settled on a design for giving priorities during option values collection in App::Easer V2.

After the initial thoughts expressed in App::Easer options collection, this is the design I adopted (text coming straight from the to-be documentation, just for sake of laziness):

Each source can be set either as a $locator string or as an array reference with the following structure:

[ $locator, @args ]

The $locator can be a reference to a sub, which is used as the source itself, or a string that allows getting the source sub to handle the specific source. Strings starting with the + character are reserved for sources provided by App::Easer::V2 out of the box.

If $locator is a plain string, it is possible to set the priority directly inside it with =NN (e.g. +Default=100). It’s not necessary to set the priority; if missing, it will be assumed to be 10 more than the previous one (with the first item starting at 10).

The @args part can provide additional arguments to the specific source; its applicability is dependent on the source itself. As the only exception, if the first item of @args is a hash reference, it will be removed from the array and used to gather additional meta-options used directly by App::Easer. At the moment, this is an alternative way to set the priority of the specific source using the key priority. This means that the following examples are equivalent:

# priority in source name, like anywhere else
[ '+FromTrail=90', qw< defaults foo baz > ],

# priority in meta-options first-arguments hash reference
[ '+FromTrail', {priority => 90}, qw< defaults foo baz > ],

It’s not necessary to set the sources explicitly, as by default the following configuration is assumed:

+CmdLine +Environment +Parent=70 +Default=100

where the respective priorities are, in order, 10, 20, 70, and 100.

Next in line will be the design of some rational way to test the alternatives and cases that can arise… wish me luck! Or time! Or will!

Stay safe!