A class is declared as:

package Class::Name;
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Constructors are anything which calls bless, you should read perltoot to get a handle on that, but if you want to ignore that Moose will provide a default constructor named new for you.

Every class gets DESTROY called right before it's garbage collected. You can hook to that. C<Moose> let's you specify sub DEMOLISH which does not have to call the super class's destructors.

Inheritence is controlled with the special variable @ISA in every package, which contains a list of base classes. YOu can use the extends keyword in Moose to clean that up a bit.

Accessors are autogenerated for you when you use attributes, like:

has name => (
   is => "rw", # what accessor to generate, can also be wo or ro
);
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I don't know what you mean by contexts - that's a very general term.