How to Specify Module Implementation At Compile Time In Elixir?

In Elixir, you can specify module implementation at compile time by using the @behaviour attribute.

The @behaviour attribute allows you to define a list of functions that a module must implement in order to adhere to a certain behavior or interface.

When a module defines a @behaviour attribute, the Elixir compiler will check that the module implements all the functions specified in the @behaviour attribute.

This helps to ensure that modules that are meant to behave in a certain way actually do so, and can help catch errors at compile time rather than at runtime.

To use the @behaviour attribute, simply add it to the module you want to specify the implementation for, followed by the name of the behavior module.

What is a compile-time macro in Elixir?

In Elixir, a compile-time macro is a piece of code that is executed during the compilation phase of a program. Macros are functions that are called at compile time to generate code that will be included in the final compiled output. This allows developers to write code that can be evaluated and manipulated at compile time, which can help in generating complex code structures and optimizing code performance. Macros are defined using the defmacro keyword in Elixir and are commonly used for code generation, abstraction, and metaprogramming.

How to set a module implementation at compile time in Elixir?

In Elixir, you can set a module implementation at compile time by using the @module_attribute directive.

Here's an example of setting a module implementation at compile time in Elixir:

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defmodule MyModule do
  @impl MyModuleImplementation
  def my_function do
    # function implementation
  end
end

defmodule MyModuleImplementation do
  def my_function do
    IO.puts "This is the implementation of my_function"
  end
end

MyModule.my_function()

In this example, we are setting the implementation of the my_function function in MyModule to be from the MyModuleImplementation module at compile time. When we call MyModule.my_function(), it will execute the implementation from MyModuleImplementation.

How to use module attributes to customize behavior at compile time?

Module attributes can be used to customize behavior at compile time by using conditional compilation directives. By setting module attributes with specific values, you can control which parts of the code are compiled or excluded based on these attributes.

Here is an example of how to use module attributes to customize behavior at compile time:

1. Define a module attribute with default value using AttributeUsage attribute:

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[AttributeUsage(AttributeTargets.Module, Inherited = false)]
public class MyCustomAttribute : Attribute
{
    public bool EnableFeature { get; }

    public MyCustomAttribute(bool enableFeature)
    {
        EnableFeature = enableFeature;
    }
}

1. Apply the MyCustomAttribute to the module:

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[assembly: MyCustomAttribute(true)]

1. Use the module attribute to conditionally compile code:

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[MyCustom(EnableFeature = true)]
public static void MyMethod()
{
    // Compile this code only if the EnableFeature attribute is set to true
}

#if FEATURE_ENABLED
MyMethod();
#endif

By using module attributes and conditional compilation directives, you can customize the behavior of your code at compile time based on the values set for these attributes. This allows you to easily enable or disable certain features or behaviors in your application without having to modify the code directly.