Module: Assistant::InputBuilder::DefaultOption

Included in:
Assistant::InputBuilder
Defined in:
lib/assistant/input_builder/default_option.rb

Overview

M1: class-time gate for the default: option — fail fast on illegal providers, warn on shared mutable literals. Pure side-effects, no interaction with the per-class definitions registry.

Instance Method Summary collapse

Instance Method Details

#process_default_option(name:, default:) ⇒ void

This method returns an undefined value.

Run the class-time gate for an input's default: provider: reject illegal providers, warn on shared mutable literals.

Parameters:

  • name (Symbol) —

    input name

  • default (Object, Proc) —

    the literal value or zero-arity Proc

Raises:

  • (ArgumentError) —

    when default is callable but not a zero-arity Proc



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# File 'lib/assistant/input_builder/default_option.rb', line 14

def process_default_option(name:, default:)
  validate_default!(name:, default:)
  warn_on_mutable_default(name:, default:)
end

#validate_default!(name:, default:) ⇒ Object

M1: a default: provider must be either a literal value or a zero-arity Proc/Lambda. Anything else that responds to #call (a Method object, a custom callable) is rejected at class-definition time.



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# File 'lib/assistant/input_builder/default_option.rb', line 23

def validate_default!(name:, default:)
  if default.is_a?(Proc) && !default.arity.zero? && default.arity != -1
    raise ArgumentError, "default: for input :#{name} must be a zero-arity Proc, got arity #{default.arity}"
  elsif !default.is_a?(Proc) && default.respond_to?(:call)
    raise ArgumentError, "default: for input :#{name} must be a literal or a zero-arity Proc, not a #{default.class}"
  end
end

#warn_on_mutable_default(name:, default:) ⇒ Object

M1: warn when a mutable literal default (unfrozen Array/Hash) is used — such a default is shared across every instance of the Service subclass and almost never what the author wants. Frozen literals and Procs are safe and pass silently.



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# File 'lib/assistant/input_builder/default_option.rb', line 35

def warn_on_mutable_default(name:, default:)
  return unless (default.is_a?(Array) || default.is_a?(Hash)) && !default.frozen?

  Kernel.warn("assistant: input :#{name} has a mutable #{default.class} default; " \
              'use `default: -> { ... }` to avoid sharing state across instances')
end