# QuickStruct [](https://travis-ci.org/active-group/quick-struct) [](https://hex.pm/packages/quick_struct)
Macro to create data structures as structs with less boilerplate.
## Installation
First, add QuickStruct to your `mix.exs` dependencies:
```elixir
def deps do
[{:quick_struct, "~> 0.1"}]
end
```
and run `$ mix deps.get`.
## Usage
```elixir
defmodule User do
use QuickStruct, [firstname: String.t, name: String.t]
end
```
Now you can use `User.t` in `@type` and `@spec` declarations. To create
instances of your data structure, use one of the following options:
```elixir
iex(3)> User.make("Jon", "Adams")
%User{firstname: "Jon", name: "Adams"}
iex(4)> User.make([name: "Adams", firstname: "Jon"])
%User{firstname: "Jon", name: "Adams"}
iex(5)> %User{name: "Adams", firstname: "Jon"}
%User{firstname: "Jon", name: "Adams"}
```
You can also define a struct without types, for instance:
```elixir
defmodule QuickStructTest.Pair do
use QuickStruct, [:first, :second]
end
```
### Resulting code
The QuickStruct macro is a very shorthand option to define a struct, a
data type and enforce all fields. The `User`-struct is equivalent to:
```elixir
@enforce_keys [:firstname, :name]
defstruct [:firstname, :name]
@type t :: %User{firstname: String.t, name: String.t}
```
The macro also provides `make`-functions as constructors and other functions, see [QuickStruct](https://hexdocs.pm/quick_struct/QuickStruct.html) for further documentation. The generated `make`-functions for the `User`-struct are equivalent to:
```elixir
@spec make(String.t, String.t) :: User.t
def make(firstname, name) do
%User{firstname: firstname, name: name}
end
@spec make([firstname: String.t, name: String.t]) :: User.t
def make(fields) do
Kernel.struct!(User, fields)
end
```
### Creating modules and structs
If you need plenty of different data structures, you can use
```elixir
require QuickStruct
QuickStruct.define_module(User, [firstname: String.t, name: String.t])
QuickStruct.define_module(Pair, [:first, :second])
```
to create a module and the corresponding struct. So this is shorthand for:
```elixir
defmodule User do
use QuickStruct, [firstname: String.t, name: String.t]
end
defmodule Pair do
use QuickStruct, [:first, :second]
end
```
## License
Copyright © 2019 Active Group GmbH
This work is free. You can redistribute it and/or modify it under the
terms of the MIT License. See the LICENSE file for more details.
