class-diagram-creator

name	class-diagram-creator
description	Use this skill to create a class diagram in markdown format for the given class.

Class Diagram Creator Skill

This skill provides guidelines and procedures for extracting class structures and generating Mermaid class diagrams for classes in the PicoLibrary project.

1. Class Extraction Process

When creating a class diagram, perform the following steps to gather necessary details:

A. Identifying Superclasses (Inheritance)

• Source: Look at the class declaration line: class ChildClass(ParentClass1, ParentClass2):.
• Filtering: Include only parent classes that are part of the PicoLibrary project (typically matching filenames in the repository starting with an uppercase letter).
• Exclusion: Ignore external/system bases (e.g., standard Python libraries or MicroPython-specific modules like machine, framebuf, etc.).
• Mermaid Syntax: Represent inheritance using <|-- (e.g., ParentClass <|-- ChildClass).

B. Identifying Attributes

• Class Attributes: Variables defined directly inside the class block (e.g., constants). Exclude private class attributes (prefixed with _).
• Instance Attributes: Look inside the __init__ constructor for assignments to self (e.g., self.pin = pin).
• Filtering: Focus on public attributes (do not start with _).
• Formatting: Format attributes in Mermaid as +name : type (e.g., +pin : int).

C. Identifying Methods

• Constructor: Include __init__.
• Public Methods: Include any functions defined within the class body that do not start with _.
• Exclusion: Exclude all private helper methods starting with _ (except __init__).
• Formatting: Format methods in Mermaid as +method_name(param1: type) : return_type.

D. Identifying Associations & Relationships

• Association (-->): A class holds a reference to another class (e.g., as a field/attribute).
• Composition (*--): A class owns and manages the lifecycle of another class (e.g., creating the sub-component inside its constructor).
• Aggregation (o--): A class uses another class instance passed into it (e.g., passed as a dependency in the constructor).
• Dependency (..>): A class temporarily references another class (e.g., as a parameter in a method call other than the constructor).

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2. Mermaid Diagram Layout & Syntax Guidelines

Generate the diagram inside a mermaid code block using classDiagram notation.

Formatting Rules

1. Visibility: Use + for public members and - for private/protected members (typically, only include public ones and __init__ unless private ones are critical to explain structural mechanics).
2. Relationships:
   • Inheritance: Parent <|-- Child
   • Composition (strong ownership): Owner *-- Owned
   • Aggregation (uses/references): Whole o-- Part
   • Association: ClassA --> ClassB
3. Clutter Control: If a class has too many attributes/methods, limit list to the top 5-7 most relevant public members.
4. Sizing: Design the diagram structure so that it fits cleanly on an 8.5x11 inch page or a single presentation slide without overlapping paths.

Example Template

classDiagram
    direction TB

    class Device {
        +__init__(pin: int)
        +turn_on() void
        +turn_off() void
    }

    class Light {
        +__init__(pin: int, color: str)
        +set_brightness(level: int) void
    }

    Device <|-- Light