alternatives.ex

# Given that we have a `User` module, that looks something like this:

defmodule User do
  defstruct [:name]
  
  def changeset(user, params) do
    # ...
  end
end

# When writing code like this, with the struct literal syntax `%Usert{}`, we create an `export` dependency on `User`:

defmodule Accounts do
  def create_user(params) do
    %User{}
    |> User.changeset(params)
    |> Repo.insert()
  end
  
  def update_user(%User{} = user, params) do
    user
    |> User.changeset(params)
    |> Repo.update()
  end
  
  def update_user(_, _) do
    raise "INVALID"
  end
end

# But when writing it like this, we only have a `runtime` dependency, while still basically doing the same thing:

defmodule Accounts do
  def create_user(params) do
    User
    |> struct!(%{})
    |> User.changeset(params)
    |> Repo.insert()
  end
  
  def update_user(%{__struct__: User} = user, params) do
    user
    |> User.changeset(params)
    |> Repo.update()
  end
  
  def update_user(_, _) do
    raise "INVALID"
  end
end