Class: Decoding::Result Abstract

Inherits:
Object
  • Object
show all
Defined in:
lib/decoding/result.rb

Overview

This class is abstract.

A result represent the outcome of some computation that can succeed or fail. The results are represented with two subclasses of Result: Ok and Err. Each hold a single result value.

The use of a result is the common interface provided to callers for transforming or chaining result values.

Direct Known Subclasses

Err, Ok

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(value) ⇒ Result

Returns a new instance of Result.



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# File 'lib/decoding/result.rb', line 52

def initialize(value)
  @value = value
  @hash = [self.class, value].hash
  freeze
end

Instance Attribute Details

#hash ⇒ Object (readonly) 



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# File 'lib/decoding/result.rb', line 50

def hash
  @hash
end

Class Method Details

.all(results) ⇒ Result<a>

Collapse array of result values into a single result, or return the first Err value.

Examples:

all(Ok(1), Ok(2)) # => Ok([1, 2])
all(Ok(1), Err("error")) # => Err("error")

Parameters:

Returns:



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# File 'lib/decoding/result.rb', line 36

def self.all(results)
  results.reduce(ok([])) do |acc, el|
    acc.and(el.to_result) { [*_1, _2] }
  end
end

.err(value) ⇒ Decoding::Err<a>

Construct a new Err value with the given value.

Parameters:

  • value (a)

Returns:



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# File 'lib/decoding/result.rb', line 26

def self.err(value) = Err.new(value)

.ok(value) ⇒ Decoding::Ok<a>

Construct a new Ok value with the given value.

Parameters:

  • value (a)

Returns:



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# File 'lib/decoding/result.rb', line 20

def self.ok(value) = Ok.new(value)

Instance Method Details

#and(other) {|left, right| ... } ⇒ Decoding::Result<c>

Combine two Result values if they are both Ok using the given block, or return the first Err value.

Parameters:

Yield Parameters:

  • left (Object)
  • right (Object)

Yield Returns:

  • (c)

Returns:



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# File 'lib/decoding/result.rb', line 136

def and(_) = self

#and_then {|value| ... } ⇒ Decoding::Result<a>

Transform a result using a block that will also return a result.

Yield Parameters:

  • value (Object)

Yield Returns:

Returns:



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# File 'lib/decoding/result.rb', line 143

def and_then = self

#deconstruct ⇒ Object 



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# File 'lib/decoding/result.rb', line 58

def deconstruct
  [value]
end

#eql?(other) ⇒ Boolean Also known as: ==

Returns:

  • (Boolean) 


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# File 'lib/decoding/result.rb', line 62

def eql?(other)
  other.is_a?(self.class) && value == other.value
end

#err? ⇒ Boolean

Whether this value is an Err value.

Returns:

  • (Boolean) 


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# File 'lib/decoding/result.rb', line 79

def err? = false

#inspect ⇒ Object 



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# File 'lib/decoding/result.rb', line 67

def inspect
  "#<#{self.class} #{value.inspect}>"
end

#map {|value| ... } ⇒ Decoding::Result<b>

Create a new Result value for the result of the block applied to this result's value. Err values are returned as-is.

Examples:

Result.ok(123).map { |i| i * 2 } # => Ok(246)
Result.err("error").map { |i| i * 2 } # => Err("error")

Yield Parameters:

  • value (a)

Yield Returns:

  • (b)

Returns:



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# File 'lib/decoding/result.rb', line 114

def map = self

#map_err {|value| ... } ⇒ Decoding::Result<b>

Create a new Result value for the result of the block applied to this result's value. Ok values are returned as-is.

Examples:

Result.ok(123).map { |s| s.upcase } # => Ok(123)
Result.err("error").map { |s| s.upcase } # => Err("ERROR")

Yield Parameters:

  • value (a)

Yield Returns:

  • (b)

Returns:



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# File 'lib/decoding/result.rb', line 125

def map_err = self

#ok? ⇒ Boolean

Whether this value is an Ok value.

Returns:

  • (Boolean) 


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# File 'lib/decoding/result.rb', line 74

def ok? = false

#to_result ⇒ Object 



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# File 'lib/decoding/result.rb', line 145

def to_result = self

#unwrap(default_value) ⇒ Object

Extract the value out of a Result value. In case of an Ok, this returns the result's value. In case of an Err, the given default_value is returned.

Parameters:

  • default_value (Object)

Returns:

  • (Object) 


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# File 'lib/decoding/result.rb', line 87

def unwrap(default_value) = default_value

#unwrap! ⇒ Object

Extract the value out of a Result value. In case of an Ok, this returns the result's value. In case of an Err, a UnwrapError is raised with the error value as its message.

Returns:

  • (Object)

Raises:



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# File 'lib/decoding/result.rb', line 95

def unwrap! = raise(UnwrapError, value.to_s)

#unwrap_err(default_value) ⇒ Object

Extract the error value out of a Result value. In case of an Err, this returns the result's value. In case of an Ok, the given default_value is returned.

Parameters:

  • default_value (Object)

Returns:

  • (Object) 


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# File 'lib/decoding/result.rb', line 103

def unwrap_err(default_value) = default_value