drawlib.diagrams.class_diagram

UML 2.0 object-oriented class diagrams featuring 3-compartment class and interface cards, member visibility prefixes, and canonical UML relationship markers. Canonical import: from drawlib.diagrams.class_diagram import ClassDiagram, ClassNode, ClassRelationship.

22_diagrams_class_1 — UML 2.0 Class Diagram with Interface Realization, Dependency, and Composition

Source Code

from drawlib.canvas import save, setup
from drawlib.diagrams.class_diagram import ClassDiagram, ClassNode
from drawlib.fonts import FontRoboto, FontSourceCode
from drawlib.styles import Colors, Styles

setup(width=120, height=64)

cd = ClassDiagram(
    node_style=Styles.Neutral.patch(text_font=FontSourceCode.ROBOTO_MONO, text_size=10.0),
    header_style=Styles.PrimaryNeutral.patch(
        text_font=FontRoboto.ROBOTO_BOLD, text_size=11.0, shape_line_color=Styles.Neutral.shape_line_color
    ),
    edge_style=Styles.DarkBold,
    edge_text_style=Styles.Dark.patch(text_size=10.0),
    margin=4.0,
)

repo_iface = cd.add(
    ClassNode(
        "Repository",
        stereotype="interface",
        width=40,
        row_height=3.8,
        header_style=Styles.PrimaryFlat.patch(
            text_color=Colors.White, text_font=FontRoboto.ROBOTO_BOLD, text_size=11.0
        ),
    ).add_method("save", "order: Order", "None"),
    xy=(25.0, 49.0),
)

sql_repo = cd.add(
    ClassNode("SqlRepository", width=40, row_height=3.8)
    .add_attribute("dsn", "str", visibility="-")
    .add_method("save", "order: Order", "None"),
    xy=(25.0, 17.0),
)

order = cd.add(
    ClassNode(
        "Order",
        width=40,
        row_height=3.8,
        header_style=Styles.SecondaryNeutral.patch(
            text_font=FontRoboto.ROBOTO_BOLD, text_size=11.0, shape_line_color=Styles.Neutral.shape_line_color
        ),
    )
    .add_attribute("id", "UUID", visibility="+")
    .add_method("total", "", "Decimal"),
    xy=(95.0, 49.0),
)

item = cd.add(
    ClassNode("OrderItem", width=40, row_height=3.8)
    .add_attribute("sku", "str", visibility="+")
    .add_attribute("qty", "int", default_value="1", visibility="+"),
    xy=(95.0, 17.0),
)

cd.connect(sql_repo, repo_iface, "realization", start_side="top", end_side="bottom")
cd.connect(repo_iface, order, "dependency", label="«persists»", start_side="right", end_side="left")
cd.connect(
    order,
    item,
    "composition",
    start_multiplicity="1",
    end_multiplicity="1..*",
    directed=True,
    start_side="bottom",
    end_side="top",
)

cd.draw(xy=(60.0, 32.0), align="center")
save()

class`AttributeInfo`#

Validated Pydantic data model representing a single class field or attribute row inside a ClassNode's attributes compartment. Typically created via node.add_attribute(...) or passed to node.add_attributes([...]).

AttributeInfo(
    *,
    name: str,
    type: str = "",
    is_public: bool = True,
    visibility: str | None = None,
    default_value: str = "",
    is_static: bool = False,
) -> None

Coordinate Anchor: Rendered left-aligned as an ordered row inside the middle compartment of ClassNode.

Constructor Parameters & Fields#

Parameter	Type	Default	Description
`name`	`str`	(Required)	Attribute or field identifier (keyword-only).
`type`	`str`	`""`	Type annotation string (e.g., `"UUID"`, `"list[Item]"`).
`is_public`	`bool`	`True`	Resolves visibility prefix to `"+"` when `True` or `"-"` when `False` unless `visibility` is specified.
`visibility`	`str \| None`	`None`	Explicit UML visibility prefix (`"+"` public, `"-"` private, `"#"` protected, `"~"` package); overrides `is_public`.
`default_value`	`str`	`""`	Optional default literal rendered as `= <default_value>`.
`is_static`	`bool`	`False`	Marks the attribute as class-level static (rendered underlined in UML).

Public Methods & Properties#

Member	Kind	Signature	Description
`display_text`	`property`	`-> str`	Formatted UML attribute string (`"{symbol} {name}: {type} = {default_value}"`).
`symbol`	`property`	`-> str`	Resolved single-character UML visibility prefix (`"+"`, `"-"`, `"#"`, or `"~"`).
`model_copy`	`method`	`(self, *, update: Mapping[str, Any] \| None = None, deep: bool = False) -> Self`	Create a shallow or deep copy with optional field updates (`pydantic.BaseModel`).
`model_dump`	`method`	`(self, *, mode: str = "python", ...) -> dict[str, Any]`	Serialize fields to a Python dictionary (`pydantic.BaseModel`).
`model_dump_json`	`method`	`(self, *, indent: int \| None = None, ...) -> str`	Serialize fields to a JSON string (`pydantic.BaseModel`).
`model_validate`	`classmethod`	`(obj: Any, *, strict: bool \| None = None, ...) -> Self`	Validate an arbitrary mapping or object into `AttributeInfo`.
`model_validate_json`	`classmethod`	`(json_data: str \| bytes \| bytearray, ...) -> Self`	Parse and validate JSON input into `AttributeInfo`.
`model_validate_strings`	`classmethod`	`(obj: Any, ...) -> Self`	Validate string-typed input dictionary into `AttributeInfo`.
`model_construct`	`classmethod`	`(_fields_set: set[str] \| None = None, **values: Any) -> Self`	Construct an unvalidated instance directly from field values.
`model_json_schema`	`classmethod`	`(by_alias: bool = True, ...) -> dict[str, Any]`	Generate a JSON Schema dictionary for `AttributeInfo`.

(Also inherits standard pydantic.BaseModel lifecycle/compatibility members: model_extra, model_fields_set, model_parametrized_name, model_post_init, model_rebuild, construct, copy, dict, from_orm, json, parse_file, parse_obj, parse_raw, schema, schema_json, update_forward_refs, and validate.)

class`ClassDiagram`#

Top-level container managing ClassNode cards, ClassRelationship connectors, and bounding-box layout for UML 2.0 class diagrams.

ClassDiagram(
    *,
    node_style: Style,
    edge_style: Style,
    edge_text_style: Style,
    title: str = "",
    title_style: Style | None = None,
    style: Style | None = None,
    width: float | None = None,
    height: float | None = None,
    margin: float = 5.0,
    header_style: Style | None = None,
) -> None

Coordinate Anchor: draw(xy=(0.0, 0.0), align="bottom_left") shifts local coordinates by xy (or centers the computed bounding box of all classes at xy when align="center").

Constructor Parameters#

Parameter	Type	Default	Description
`node_style`	`Style`	(Required)	Base style for class card bodies, compartment dividers, and member text (keyword-only).
`edge_style`	`Style`	(Required)	Base stroke and marker style for `ClassRelationship` lines (keyword-only).
`edge_text_style`	`Style`	(Required)	Base typography style for relationship labels, multiplicities, and role names (keyword-only).
`title`	`str`	`""`	Optional diagram title rendered centered above the top border.
`title_style`	`Style \| None`	`None`	Optional typography style override for `title`.
`style`	`Style \| None`	`None`	Optional outer background/border style for the diagram container.
`width`	`float \| None`	`None`	Optional fixed diagram width override (`None` auto-computes from `get_bounds()` + `margin`).
`height`	`float \| None`	`None`	Optional fixed diagram height override (`None` auto-computes from `get_bounds()` + `margin`).
`margin`	`float`	`5.0`	Outer margin padding surrounding all registered classes.
`header_style`	`Style \| None`	`None`	Optional default style applied to top class header compartments unless overridden per node.

Public Methods & Properties#

Member	Kind	Signature	Description
`add`	`method`	`(self, class_node: ClassNode, xy: tuple[float, float] = (0.0, 0.0), show: bool \| None = None) -> ClassNode`	Register a `ClassNode` centered at local coordinate `xy` and return it.
`add_relationship`	`method`	`(self, rel: ClassRelationship) -> ClassRelationship`	Register a pre-constructed `ClassRelationship` with this diagram.
`connect`	`method`	`(self, source: ClassNode, target: ClassNode, relationship_type: RelationshipType = "association", *, type: RelationshipType \| None = None, label: str = "", start_side: Side = "auto", end_side: Side = "auto", start_multiplicity: str = "", end_multiplicity: str = "", start_role: str = "", end_role: str = "", directed: bool = False, style: Style \| None = None, text_style: Style \| None = None, routing: RoutingType = "orthogonal", padding: PaddingType = 0.0, show: bool = True) -> ClassRelationship`	Create and register a UML `ClassRelationship` between `source` and `target`.
`draw`	`method`	`(self, xy: tuple[float, float] = (0.0, 0.0), *, align: Literal["bottom_left", "center"] = "bottom_left", scale: PosFloat = 1.0) -> None`	Render the complete class diagram onto the active canvas anchored at `xy`.
`get_bounds`	`method`	`(self) -> tuple[float, float, float, float]`	Compute enclosing `(min_x, min_y, max_x, max_y)` of all registered class cards.
`get_size`	`method`	`(self) -> tuple[float, float]`	Compute overall `(width, height)` of the diagram including `margin`.

class`ClassNode`#

UML 2.0 3-compartment box representing a concrete class, abstract class, interface, enum, or dataclass.

ClassNode(
    name: str,
    stereotype: str = "",
    is_abstract: bool = False,
    width: float = 28.0,
    height: float | None = None,
    header_height: float | None = None,
    row_height: float = 3.2,
    style: Style | None = None,
    header_style: Style | None = None,
    show: bool = True,
) -> None

Coordinate Anchor: Center (cx, cy) when registered via cd.add(node, xy=(cx, cy)). When using saturated header fills such as Styles.PrimaryFlat, pass header_style=Styles.PrimaryFlat.patch(text_color=Colors.White, text_size=11.0) for crisp contrast.

Constructor Parameters#

Parameter	Type	Default	Description
`name`	`str`	(Required)	Class or interface name displayed in the top header compartment.
`stereotype`	`str`	`""`	Optional UML stereotype (auto-formatted as `<<stereotype>>` if unbracketed, e.g., `"interface"`).
`is_abstract`	`bool`	`False`	Marks the class as abstract (displays `<<abstract>>` when `stereotype` is empty).
`width`	`float`	`28.0`	Class card width in local diagram units.
`height`	`float \| None`	`None`	Optional fixed total height override (`None` auto-expands from header + member rows).
`header_height`	`float \| None`	`None`	Optional fixed header height (`None` defaults to `5.2`, or `6.5` with stereotype/abstract tag).
`row_height`	`float`	`3.2`	Vertical height per attribute or method row.
`style`	`Style \| None`	`None`	Optional body fill, border, and member text style override (falls back to `cd.node_style`).
`header_style`	`Style \| None`	`None`	Optional header compartment fill/border/text style override (falls back to `cd.header_style`).
`show`	`bool`	`True`	Visibility flag (`False` hides this class card and its relationships).

Public Methods & Properties#

Member	Kind	Signature	Description
`add_attribute`	`method`	`(self, name: str, type: str = "", is_public: bool = True, visibility: str \| None = None, default_value: str = "", is_static: bool = False) -> ClassNode`	Append a field row (`AttributeInfo`) to the attributes compartment and return `self`.
`add_attributes`	`method`	`(self, attributes: Sequence[Sequence[Any] \| AttributeInfo]) -> ClassNode`	Append multiple attributes from `(name, type, ...)` tuples or `AttributeInfo` objects and return `self`.
`add_method`	`method`	`(self, name: str, params: str = "", return_type: str = "", is_public: bool = True, visibility: str \| None = None, is_static: bool = False, is_abstract: bool = False) -> ClassNode`	Append an operation row (`MethodInfo`) to the methods compartment and return `self`.
`add_methods`	`method`	`(self, methods: Sequence[Sequence[Any] \| MethodInfo]) -> ClassNode`	Append multiple methods from `(name, params, return_type, ...)` tuples or `MethodInfo` objects and return `self`.
`center`	`property`	`-> tuple[float, float]`	Relative center coordinate `(cx, cy)` of the class card.
`effective_height`	`property`	`-> float`	Computed total rendered height of the class card across all compartments.
`get_anchor`	`method`	`(self, side: Side) -> tuple[float, float]`	Return boundary midpoint coordinate on `side` (`"left"`, `"right"`, `"top"`, `"bottom"`, `"auto"`).
`get_bounds`	`method`	`(self) -> tuple[float, float, float, float]`	Return local bounding box `(-width/2, -effective_height/2, width/2, effective_height/2)` relative to `(0, 0)`.
`xy`	`property`	`-> tuple[float, float]`	Alias returning the relative center coordinate `(cx, cy)` of the class card.

class`ClassRelationship`#

UML 2.0 relationship edge connecting two ClassNode boxes with hollow triangles, solid/hollow diamonds, open arrowheads, multiplicities, and role labels.

ClassRelationship(
    start: ClassNode,
    end: ClassNode,
    relationship_type: RelationshipType = "association",
    start_side: Side = "auto",
    end_side: Side = "auto",
    label: str = "",
    start_multiplicity: str = "",
    end_multiplicity: str = "",
    start_role: str = "",
    end_role: str = "",
    directed: bool = False,
    style: Style | None = None,
    text_style: Style | None = None,
    routing: RoutingType = "orthogonal",
    padding: PaddingType = 0.0,
    show: bool = True,
) -> None

Coordinate Anchor: Connects start_side boundary port on start to end_side boundary port on end. Register via cd.connect(...) or cd.add_relationship(rel).

Constructor Parameters & Attributes#

Parameter	Type	Default	Description
`start`	`ClassNode`	(Required)	Source class (subclass for inheritance/realization; whole/owner for composition/aggregation).
`end`	`ClassNode`	(Required)	Target class (superclass/interface for inheritance/realization; part/member for composition/aggregation).
`relationship_type`	`RelationshipType`	`"association"`	UML relationship kind controlling stroke dash and endpoint markers.
`start_side`	`Side`	`"auto"`	Attachment side on `start` (`"left"`, `"right"`, `"top"`, `"bottom"`, `"auto"`).
`end_side`	`Side`	`"auto"`	Attachment side on `end` (`"left"`, `"right"`, `"top"`, `"bottom"`, `"auto"`).
`label`	`str`	`""`	Midpoint stereotype or verb phrase label (e.g., `"<<creates>>"`).
`start_multiplicity`	`str`	`""`	Multiplicity string rendered near the `start` anchor (e.g., `"1"`, `"0..1"`).
`end_multiplicity`	`str`	`""`	Multiplicity string rendered near the `end` anchor (e.g., `""`, `"1.."`).
`start_role`	`str`	`""`	Role name rendered near the `start` anchor.
`end_role`	`str`	`""`	Role name rendered near the `end` anchor.
`directed`	`bool`	`False`	Draws a navigable open V-arrow at `end` on `"association"`, `"aggregation"`, or `"composition"`.
`style`	`Style \| None`	`None`	Optional stroke style override (falls back to `cd.edge_style`).
`text_style`	`Style \| None`	`None`	Optional typography style override for labels/multiplicities (falls back to `cd.edge_text_style`).
`routing`	`RoutingType`	`"orthogonal"`	Path routing strategy (`"orthogonal"` or `"direct"`).
`padding`	`float \| tuple[float, float]`	`0.0`	Clearance gap between class borders and line endpoints.
`show`	`bool`	`True`	Whether to render this relationship edge.

class`MethodInfo`#

Validated Pydantic data model representing a single class method or operation row inside a ClassNode's methods compartment. Typically created via node.add_method(...) or passed to node.add_methods([...]).

MethodInfo(
    *,
    name: str,
    params: str = "",
    return_type: str = "",
    is_public: bool = True,
    visibility: str | None = None,
    is_static: bool = False,
    is_abstract: bool = False,
) -> None

Coordinate Anchor: Rendered left-aligned as an ordered row inside the bottom compartment of ClassNode.

Constructor Parameters & Fields#

Parameter	Type	Default	Description
`name`	`str`	(Required)	Method name with or without parentheses (keyword-only).
`params`	`str`	`""`	Parameter list signature string (e.g., `"order_id: UUID"`).
`return_type`	`str`	`""`	Return type annotation string (e.g., `"Order \| None"`).
`is_public`	`bool`	`True`	Resolves visibility prefix to `"+"` when `True` or `"-"` when `False` unless `visibility` is specified.
`visibility`	`str \| None`	`None`	Explicit UML visibility prefix (`"+"`, `"-"`, `"#"`, `"~"`); overrides `is_public`.
`is_static`	`bool`	`False`	Marks the method as static (`@staticmethod` / `@classmethod`, rendered underlined).
`is_abstract`	`bool`	`False`	Marks the method as abstract (`{abstract}` suffix / italic semantics).

Public Methods & Properties#

Member	Kind	Signature	Description
`display_text`	`property`	`-> str`	Formatted UML operation string (`"{symbol} {name}({params}): {return_type}"`).
`symbol`	`property`	`-> str`	Resolved single-character UML visibility prefix (`"+"`, `"-"`, `"#"`, or `"~"`).
`model_copy`	`method`	`(self, *, update: Mapping[str, Any] \| None = None, deep: bool = False) -> Self`	Create a shallow or deep copy with optional field updates (`pydantic.BaseModel`).
`model_dump`	`method`	`(self, *, mode: str = "python", ...) -> dict[str, Any]`	Serialize fields to a Python dictionary (`pydantic.BaseModel`).
`model_dump_json`	`method`	`(self, *, indent: int \| None = None, ...) -> str`	Serialize fields to a JSON string (`pydantic.BaseModel`).
`model_validate`	`classmethod`	`(obj: Any, *, strict: bool \| None = None, ...) -> Self`	Validate an arbitrary mapping or object into `MethodInfo`.
`model_validate_json`	`classmethod`	`(json_data: str \| bytes \| bytearray, ...) -> Self`	Parse and validate JSON input into `MethodInfo`.
`model_validate_strings`	`classmethod`	`(obj: Any, ...) -> Self`	Validate string-typed input dictionary into `MethodInfo`.
`model_construct`	`classmethod`	`(_fields_set: set[str] \| None = None, **values: Any) -> Self`	Construct an unvalidated instance directly from field values.
`model_json_schema`	`classmethod`	`(by_alias: bool = True, ...) -> dict[str, Any]`	Generate a JSON Schema dictionary for `MethodInfo`.

type`RelationshipType`#

Literal union specifying the 6 canonical UML 2.0 class relationship kinds (plus concise verb aliases) accepted by ClassDiagram.connect() and ClassRelationship.

RelationshipType = Literal[
    "inheritance",
    "realization",
    "composition",
    "aggregation",
    "association",
    "dependency",
    "inherit",
    "realize",
    "composite",
    "aggregate",
    "associate",
    "depend",
]

Coordinate Anchor: Determines marker geometry at start (diamonds) and end (hollow triangles or open V-arrows).

Canonical Value	Short Alias	Stroke	`start` Marker	`end` Marker	UML Meaning
`"inheritance"`	`"inherit"`	Solid	None	Hollow triangle (`▷`)	`start` subclass extends `end` superclass.
`"realization"`	`"realize"`	Dashed	None	Hollow triangle (`▷`)	`start` class implements `end` interface.
`"composition"`	`"composite"`	Solid	Solid diamond (`◆`)	Open arrow if `directed=True`	`start` strongly owns lifecycle of `end`.
`"aggregation"`	`"aggregate"`	Solid	Hollow diamond (`◇`)	Open arrow if `directed=True`	`start` references shared `end` instance.
`"association"`	`"associate"`	Solid	None	Open arrow if `directed=True`	Structural association between `start` and `end`.
`"dependency"`	`"depend"`	Dashed	None	Open V-arrow (`>`)	`start` transiently depends on `end`.

type`RoutingType`#

Literal type controlling path routing for ClassRelationship connectors.

RoutingType = Literal["orthogonal", "direct"]

Coordinate Anchor: Governs connector routing between resolved start and end class boundary ports.

Literal Value	Path Geometry
`"orthogonal"`	Right-angled horizontal and vertical Manhattan segments (default).
`"direct"`	Straight Euclidean segment connecting the resolved ports.

type`Side`#

Literal type selecting the attachment edge on a ClassNode box.

Side = Literal["left", "right", "top", "bottom", "auto"]

Coordinate Anchor: "left", "right", "top", and "bottom" attach to the midpoint of that class card edge; "auto" chooses the nearest facing side automatically.

drawlib.diagrams.class_diagram

classAttributeInfo#

Constructor Parameters & Fields#

Public Methods & Properties#

classClassDiagram#

Constructor Parameters#

Public Methods & Properties#

classClassNode#

Constructor Parameters#

Public Methods & Properties#

classClassRelationship#

Constructor Parameters & Attributes#

classMethodInfo#

Constructor Parameters & Fields#

Public Methods & Properties#

typeRelationshipType#

typeRoutingType#

typeSide#

class`AttributeInfo`#

class`ClassDiagram`#

class`ClassNode`#

class`ClassRelationship`#

class`MethodInfo`#

type`RelationshipType`#

type`RoutingType`#

type`Side`#