QuickStruct

Macro to create data structures as structs with less boilerplate.

Installation

First, add QuickStruct to your mix.exs dependencies:

defdepsdo[{:quick_struct,"~> 0.1"}]end

and run $ mix deps.get.

Usage

defmoduleUserdouseQuickStruct,[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:

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:

defmoduleQuickStructTest.PairdouseQuickStruct,[: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:

@enforce_keys[:firstname,:name]defstruct[:firstname,:name]@typet::%User{firstname: String.t,name: String.t}

The macro also provides make-functions as constructors and other functions, see QuickStruct for further documentation. The generated make-functions for the User-struct are equivalent to:

@specmake(String.t,String.t)::User.tdefmake(firstname,name)do%User{firstname: firstname,name: name}end@specmake([firstname: String.t,name: String.t])::User.tdefmake(fields)doKernel.struct!(User,fields)end

Generating predicates

The optional argument :predicate can be used to generate a predicate for the struct:

defmoduleUserWithPredicatedouseQuickStruct,[firstname: String.t,name: String.t],predicate: :user?end

iex>user=User.make("Jon","Adams")%User{firstname: "Jon",name: "Adams"}iex>User.user?(user)trueiex>User.user?(non_user_struct)falseiex>User.user?(1)false

Creating modules and structs

If you need plenty of different data structures, you can use

requireQuickStructQuickStruct.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:

defmoduleUserdouseQuickStruct,[firstname: String.t,name: String.t]enddefmodulePairdouseQuickStruct,[:first,:second]end

License

Copyright © 2021 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.