# [`«symb»`](https://github.com/ikko/symb) cookbook

**Recipes for Symbolic Mastery**

_Recipe 1: How to Create a Mixin?_

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# 1.5 Documenting Your Mixin: Clarity and Usability

Effective documentation is paramount for the usability and maintainability of your mixins. Clear and comprehensive documentation helps other developers (and your future self) understand what your mixin does, how to use it, and any specific considerations. This section outlines key aspects of documenting your `symb` mixins.

## Why Document Mixins?

*   **Clarity:** Explains the purpose and functionality of the mixin.
*   **Usability:** Provides instructions and examples for how to integrate and use the mixin.
*   **Maintainability:** Facilitates future modifications and debugging by clearly outlining design choices and dependencies.
*   **Collaboration:** Enables other developers to quickly grasp and contribute to your mixin.

## Key Documentation Elements

### 1. Docstrings

Every mixin class, its methods, and properties should have clear and concise docstrings. Follow a consistent style (e.g., reStructuredText, Google, or NumPy style) for your docstrings. They should explain:

*   **Class Docstring:** The overall purpose of the mixin, what functionality it adds, and to which `Symbol` objects it is intended to be applied.
*   **Method/Property Docstring:** A brief description of what the method/property does, its parameters (with types and descriptions), what it returns, and any exceptions it might raise.

**Example Docstring for `DescendantCounterMixin`:**

```python
class DescendantCounterMixin:
    """A mixin for Symbol objects that provides methods to count their descendants.

    This mixin adds both synchronous and asynchronous methods to traverse
    the symb's graph and determine the total number of unique descendant symbs.
    """
    def __init__(self, symb_instance: Symbol):
        """Initializes the DescendantCounterMixin.

        Args:
            symb_instance: The Symbol instance to which this mixin is applied.
        """
        self.symb = symb_instance

    def count_descendants(self) -> int:
        """Counts the total number of unique descendants for this symb.

        Performs a breadth-first search starting from the symb's children
        to identify all unique symbs reachable within its sub-graph.

        Returns:
            The total count of unique descendant symbs.
        """
        # ... implementation ...

    async def a_count_descendants(self) -> int:
        """Asynchronously counts the total number of unique descendants.

        This asynchronous version provides a non-blocking way to perform
        the descendant counting operation. In more complex scenarios,
        it would leverage async I/O or offload CPU-bound tasks.

        Returns:
            The total count of unique descendant symbs.
        """
        # ... implementation ...
```

### 2. Type Hints

As demonstrated in the docstring example, use Python's type hints (`typing` module) extensively. Type hints improve code readability, enable static analysis tools to catch errors early, and serve as a form of executable documentation, clearly indicating expected input types and return types.

### 3. Example Usage

Include small, runnable code examples within your docstrings or in a separate `examples/` directory. Examples are invaluable for demonstrating how to instantiate the mixin and call its methods, especially for new users.

### 4. Dedicated `README.md` (for complex mixins)

For more complex mixins or collections of related mixins, consider creating a dedicated `README.md` file within their directory. This file can provide:

*   A higher-level overview of the mixin's capabilities.
*   Detailed installation instructions (if applicable).
*   More extensive usage examples.
*   Information on dependencies.
*   Design considerations or architectural notes.
*   Contribution guidelines.

### 5. Integration with `symb` Documentation

Finally, ensure your mixin is referenced and explained within the main `symb` project documentation (e.g., in the API reference, user manual, or cookbook). This provides a centralized location for users to discover and learn about available mixins.

By consistently applying these documentation practices, you contribute to a more accessible, understandable, and robust `symb` ecosystem.
