Set of additional functionality for structs
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README.md

Pyc

CircleCI  Struct on steroids: insertion validation, handy pipelining and more.

Usage

Declare the struct with use Pyc, definition: ... and get helper macros to deal with the struct alongside the validation of updates for free.

Validation of updates works for all injected MyStruct.put/3 functions that basically substitute the generic Map.put/3 as well as for Collectable.into/1 automatically implemented for the struct defined that way.

All functions declared with defmethod/3 get this local variable as well as the bunch of local variables for all the keys of the struct.

Easy monadic chaining is possible with generic pipe operator.

defmodule MyStruct do
  use Pyc,
    definition: [foo: 42, bar: %{}, baz: []],
    constraints: [%{matches: %{foo: 42, bar: ~Q[bar]}, guards: %{check_bar: "is_map(bar)"}}]

  defmethod :foo!, [value] when foo < 100 and length(baz) > 0 do
    %__MODULE__{this | foo: value, baz: [42 | baz]}
  end
end


iex> %MyStruct{}
...> |> MyStruct.put(:baz, 42)
...> |> IO.inspect(label: "1st put")
...> |> MyStruct.put(:baz, [])
...> |> IO.inspect(label: "2nd put")
...> |> MyStruct.put(:bar, 42)
...> |> IO.inspect(label: "3rd put")
#⇒ 1st put: %MyStruct{bar: %{}, baz: 42, foo: 42}
#  2nd put: %MyStruct{bar: %{}, baz: [], foo: 42}
#  3rd put: {:error, %MyStruct{bar: 42, baz: [], foo: 42}}

iex> Enum.into([bar: %{zzz: nil}, baz: "¡Hola!"], %MyStruct)
#⇒ %MyStruct{bar: %{zzz: nil}, baz: "¡Hola!", foo: 42}

iex> Enum.into([bar: 42], %MyStruct)
#⇒ {:error, %MyStruct{bar: 42, baz: [], foo: 42}}

Installation

def deps do
  [
    {:pyc, "~> 0.1.0"}
  ]
end

Docs

https://hexdocs.pm/pyc