StructyRecord

StructyRecord provides a Struct-like interface for your Records.

• Use your record's macros in the same module where it is defined!
• Access and update fields in your record through named macro calls.
• Create and update records at runtime (not limited to compile time).
• Calculate 1-based indexes to access record fields in :ets tables.

Setup

The package is available in Hex and can be installed by adding structy_record to your list of dependencies in mix.exs:

def deps do
  [
    {:structy_record, "~> 0.2.1"}
  ]
end

Usage

To get started, see the documentation for StructyRecord.defrecord/3:

iex> h StructyRecord.defrecord

Examples

Activate this macro in your environment:

require StructyRecord

Define a structy record for a rectangle:

StructyRecord.defrecord Rectangle, [:width, :height] do
  def area(r = record()) do
    get_width(r) * get_height(r)
  end

  def perimeter(record(width: w, height: h)) do
    2 * (w + h)
  end

  def square?(record(width: same, height: same)), do: true
  def square?(_), do: false
end

Activate its macros in your environment:

use Rectangle

Create instances of your structy record:

rect = Rectangle.{}                        #-> {Rectangle, nil, nil}
rect = Rectangle.{[]}                      #-> {Rectangle, nil, nil}
no_h = Rectangle.{[width: 1]}              #-> {Rectangle, 1, nil}
no_w = Rectangle.{[height: 2]}             #-> {Rectangle, nil, 2}
wide = Rectangle.{[width: 10, height: 5]}  #-> {Rectangle, 10, 5}
tall = Rectangle.{[width: 4, height: 25]}  #-> {Rectangle, 4, 25}
even = Rectangle.{[width: 10, height: 10]} #-> {Rectangle, 10, 10}

Inspect the contents of those instances:

rect |> Rectangle.inspect() #-> "Rectangle.{[width: nil, height: nil]}"
no_h |> Rectangle.inspect() #-> "Rectangle.{[width: 1, height: nil]}"
no_w |> Rectangle.inspect() #-> "Rectangle.{[width: nil, height: 2]}"
wide |> Rectangle.inspect() #-> "Rectangle.{[width: 10, height: 5]}"
tall |> Rectangle.inspect() #-> "Rectangle.{[width: 4, height: 25]}"
even |> Rectangle.inspect() #-> "Rectangle.{[width: 10, height: 10]}"

Get values of fields in those instances:

Rectangle.{{tall, :height}}       #-> 25
Rectangle.{[height: h]} = tall; h #-> 25
tall |> Rectangle.get_height()    #-> 25

Set values of fields in those instances:

Rectangle.{{even, width: 1}}    #-> {Rectangle, 1, 10}
even |> Rectangle.put(width: 1) #-> {Rectangle, 1, 10}
even |> Rectangle.put_width(1)  #-> {Rectangle, 1, 10}

Rectangle.{{even, width: 1, height: 2}}                   #-> {Rectangle, 1, 2}
even |> Rectangle.put(width: 1, height: 2)                #-> {Rectangle, 1, 2}
even |> Rectangle.put_width(1) |> Rectangle.put_height(2) #-> {Rectangle, 1, 2}

Use your custom code on those instances:

rect |> Rectangle.area() #-> (ArithmeticError) bad argument in arithmetic expression: nil * nil
no_h |> Rectangle.area() #-> (ArithmeticError) bad argument in arithmetic expression: 1 * nil
no_w |> Rectangle.area() #-> (ArithmeticError) bad argument in arithmetic expression: nil * 2
wide |> Rectangle.area() #-> 50
tall |> Rectangle.area() #-> 100
even |> Rectangle.area() #-> 100

rect |> Rectangle.perimeter() #-> (ArithmeticError) bad argument in arithmetic expression: nil + nil
no_h |> Rectangle.perimeter() #-> (ArithmeticError) bad argument in arithmetic expression: 1 + nil
no_w |> Rectangle.perimeter() #-> (ArithmeticError) bad argument in arithmetic expression: nil + 2
wide |> Rectangle.perimeter() #-> 30
tall |> Rectangle.perimeter() #-> 58
even |> Rectangle.perimeter() #-> 40

rect |> Rectangle.square?() #-> true
no_h |> Rectangle.square?() #-> false
no_w |> Rectangle.square?() #-> false
wide |> Rectangle.square?() #-> false
tall |> Rectangle.square?() #-> false
even |> Rectangle.square?() #-> true

License

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(the ISC license)

Copyright 2019 Suraj N. Kurapati https://github.com/sunaku

Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.