How deeply does The Well-Grounded Rubyist, Fourth Edition cover protected_instance_methods?

Explains receiver scope and inheritance filtering, but does not develop protected-method dispatch internals.

Protected_instance_methods

As explained in The Well-Grounded Rubyist, Fourth Edition

protected_instance_methods is a Ruby Module method that returns the protected instance methods available from a class or module, optionally including inherited and included methods.

protected_instance_methods is a Module method for inspecting protected instance methods on a class or module. Unlike obj.protected_methods, which examines a regular object's available methods, it queries the instance-method definitions associated with the class or module itself. section 7.7.3 section 15.2.3

Choose the scope of the method list with an optional argument:

protected_instance_methods returns protected instance methods from the receiver and, by default, its ancestor classes and modules. section 15.2.3
protected_instance_methods(false) restricts the result to methods defined directly by the queried class or module. section 15.2.3
Related queries include instance_methods for public and protected methods, public_instance_methods for public methods, and private_instance_methods for private methods. section 15.2.3
Keeping the receiver and requested scope clear prevents confusion between a class or module query and an object-level query. section 7.7.3

Inspecting only a class's protected definitions

Use the same receiver-and-scope pattern shown by other class-level queries: Range.protected_instance_methods(false) asks for protected instance methods defined by Range itself, while Range.protected_instance_methods also includes definitions supplied by ancestors and included modules. The false form is useful when narrowing a method list to the class's own definitions. section 15.2.3 section 7.7.3

>> Range.instance_methods(false).sort
=>  [:%, :==, :===, :begin, :bsearch, :count, :cover?, :each, :end,
 :entries, :eql?, :exclude_end?, :first, :hash, :include?, :inspect,
 :last, :max, :member?, :min, :minmax, :overlap?, :pretty_print,
 :reverse_each, :size, :step, :to_a, :to_s]

Compare Range.instance_methods(false) with the corresponding protected-instance query to see how the false argument narrows inspection to definitions made directly by the receiver. section 15.2.3

How The Well-Grounded Rubyist, Fourth Edition covers it

Cover of The Well-Grounded Rubyist, Fourth Edition

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Related concepts

instance_methodcontrasts with · instance_method is a Ruby class method that returns an unbound method object for an instance method.
instance_methodscontrasts with · instance_methods is a Ruby Module method that returns the public and protected instance methods available from a class or module, optionally including inherited and included methods.
private_instance_methodscontrasts with · private_instance_methods is a Ruby Module method that returns the private instance methods available from a class or module, optionally including inherited and included methods.

This explainer was generated by Manning's knowledge graph from the text of The Well-Grounded Rubyist, Fourth Edition. The section links point to the parts of the book it draws on.