Module: Xqsr3::Diagnostics::Exceptions::WithCause

Defined in:
lib/xqsr3/diagnostics/exceptions/with_cause.rb

Overview

This inclusion module adds to an exception class the means to chain a cause (aka inner-exception), which is then exposed with the cause attribute

Examples:

Passing an exception cause as a parameter

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#cause ⇒ Object (readonly)

The cause / inner-exception, if any, specified to the instance initialiser



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# File 'lib/xqsr3/diagnostics/exceptions/with_cause.rb', line 138

def cause
  @cause
end

#options ⇒ Object (readonly)

The options passed to the initialiser, with :cause removed, if present



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# File 'lib/xqsr3/diagnostics/exceptions/with_cause.rb', line 142

def options
  @options
end

Instance Method Details

#chained_backtrace ⇒ Object

A combination of the backtrace(s) of all chained exception(s)



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# File 'lib/xqsr3/diagnostics/exceptions/with_cause.rb', line 180

def chained_backtrace

	b = backtrace

	return b unless cause

	cb = cause.respond_to?(:chained_backtrace) ? cause.chained_backtrace : cause.backtrace

	(cb - b) + b
end

#chained_message(**options) ⇒ Object 



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# File 'lib/xqsr3/diagnostics/exceptions/with_cause.rb', line 144

def chained_message **options

	return message unless cause
	return message if @uses_cause_message

	m	=	message
	c	=	cause
	cm	=	c.respond_to?(:chained_message) ? c.chained_message(**options) : c.message

	return m if (cm || '').empty?
	return cm if (m || '').empty?

	sep	=	options[:separator] || ': '

	"#{m}#{sep}#{cm}"
end

#chainees ⇒ Object

An array of exceptions in the chain, excluding self



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# File 'lib/xqsr3/diagnostics/exceptions/with_cause.rb', line 162

def chainees

	return [] unless cause

	r = [ cause ]

	r += cause.chainees if cause.respond_to? :chainees

	r
end

#exceptions ⇒ Object

An array of exceptions in the chain, including self



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# File 'lib/xqsr3/diagnostics/exceptions/with_cause.rb', line 174

def exceptions

	[ self ] + chainees
end

#initialize(*args, **options) ⇒ Object

Defines an initializer for an exception class that allows a cause (aka an inner exception) to be specified, either as the first or last argument or as a :cause option

Signature

  • Parameters:

- 
- +option+::

  • Options:

  • :cause - The exception to be used as a cause, and ensures that that is not inferred from the arguments. May be nil to ensure that no cause is inferred



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# File 'lib/xqsr3/diagnostics/exceptions/with_cause.rb', line 83

def initialize(*args, **options)

	@uses_cause_message = false

	cz = options[:cause]

	if cz

		options = options.reject { |k, v| k == :cause }

		@has_implicit_message = args.empty?

		super *args

		warn 'unexpected implicit message' if @has_implicit_message && self.message != self.class.to_s

		@cause = cz
	else

		cz_ix = args.index { |arg| ::Exception === arg }

		if cz_ix

			args = args.dup

			cz = args.delete_at cz_ix

			if args.empty?

				if !(cz.message || '').empty? && cz.class.to_s != cz.message

					@uses_cause_message = true

					args = [ cz.message ]
				end
			end
		else

			cz = $!
		end

		@has_implicit_message = args.empty?

		super *args

		warn 'unexpected implicit message' if @has_implicit_message && self.message != self.class.to_s

		@cause = cz
	end

	@options = options
end