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

Constant Summary collapse

INSPECT_HIDDEN_FIELDS =

Array of hidden fields

[ 'has_implicit_message', 'uses_cause_message' ]

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



139
140
141
 
# File 'lib/xqsr3/diagnostics/exceptions/with_cause.rb', line 139

def cause
  @cause
end

#options ⇒ Object (readonly)

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



143
144
145
 
# File 'lib/xqsr3/diagnostics/exceptions/with_cause.rb', line 143

def options
  @options
end

Instance Method Details

#chained_backtrace ⇒ Object

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



190
191
192
193
194
195
196
197
198
199
 
# File 'lib/xqsr3/diagnostics/exceptions/with_cause.rb', line 190

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

Message obtained by concatenation of all chained exceptions’ messages

Signature

  • Parameters:

    - +options+ Options hash

  • Options:

    - +:separator+ (String) A string used to separate each chained exception message. Defaults to ": "



154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
 
# File 'lib/xqsr3/diagnostics/exceptions/with_cause.rb', line 154

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



172
173
174
175
176
177
178
179
180
181
 
# File 'lib/xqsr3/diagnostics/exceptions/with_cause.rb', line 172

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



184
185
186
187
 
# File 'lib/xqsr3/diagnostics/exceptions/with_cause.rb', line 184

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:

  • args 0+ arguments passed through to the include-ing class’ initialiser

  • options Options hash

  • 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



84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
 
# File 'lib/xqsr3/diagnostics/exceptions/with_cause.rb', line 84

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