Add type aliases that reflect their semantics

Using Any or str in type annotations might increase the need for extra
comments to explain the real valid values. However, such needs can be
drastically reduced with the help of semanticly named type aliases.

src/wireviz/DataClasses.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
-from typing import Optional, List, Any, Union
+from typing import Optional, List, Union
 from dataclasses import dataclass, field, InitVar
 from pathlib import Path
 from wireviz.wv_helper import int2tuple, aspect_ratio
@@ -10,20 +10,29 @@
 # Literal type aliases below are commented to avoid requiring python 3.8
 ConnectorMultiplier = str  # = Literal['pincount', 'populated']
 CableMultiplier = str  # = Literal['wirecount', 'terminations', 'length', 'total_length']
+ImageScale = str  # = Literal['false', 'true', 'width', 'height', 'both']
+
+Designator = str # Case insensitive unique name of connector or cable
+Pin = Union[int, str] # Pin identifier
+Wire = Union[int, str] # Wire number or 's' for shield
+MLstr = str # Multi-line string where any newline is properly handled
+Color = str # Two-letter color name = Literal[wv_colors._color_hex.keys()]
+Colors = str # One or more two-letter color names (Color) concatenated into one string
+ColorScheme = str # Color scheme name = Literal[wv_colors.COLOR_CODES.keys()]
 
 
 @dataclass
 class Image:
     gv_dir: InitVar[Path] # Directory of .gv file injected as context during parsing
     # Attributes of the image object <img>:
     src: str
-    scale: Optional[str] = None  # false | true | width | height | both
+    scale: Optional[ImageScale] = None
     # Attributes of the image cell <td> containing the image:
     width: Optional[int] = None
     height: Optional[int] = None
     fixedsize: Optional[bool] = None
     # Contents of the text cell <td> just below the image cell:
-    caption: Optional[str] = None
+    caption: Optional[MLstr] = None
     # See also HTML doc at https://graphviz.org/doc/info/shapes.html#html
 
     def __post_init__(self, gv_dir):
@@ -49,10 +58,10 @@ def __post_init__(self, gv_dir):
 
 @dataclass
 class AdditionalComponent:
-    type: str
-    subtype: Optional[str] = None
-    manufacturer: Optional[str] = None
-    mpn: Optional[str] = None
+    type: MLstr
+    subtype: Optional[MLstr] = None
+    manufacturer: Optional[MLstr] = None
+    mpn: Optional[MLstr] = None
     pn: Optional[str] = None
     qty: float = 1
     unit: Optional[str] = None
@@ -65,25 +74,25 @@ def description(self) -> str:
 
 @dataclass
 class Connector:
-    name: str
-    manufacturer: Optional[str] = None
-    mpn: Optional[str] = None
+    name: Designator
+    manufacturer: Optional[MLstr] = None
+    mpn: Optional[MLstr] = None
     pn: Optional[str] = None
     style: Optional[str] = None
     category: Optional[str] = None
-    type: Optional[str] = None
-    subtype: Optional[str] = None
+    type: Optional[MLstr] = None
+    subtype: Optional[MLstr] = None
     pincount: Optional[int] = None
     image: Optional[Image] = None
-    notes: Optional[str] = None
-    pinlabels: List[Any] = field(default_factory=list)
-    pins: List[Any] = field(default_factory=list)
-    color: Optional[str] = None
+    notes: Optional[MLstr] = None
+    pinlabels: List[Pin] = field(default_factory=list)
+    pins: List[Pin] = field(default_factory=list)
+    color: Optional[Color] = None
     show_name: Optional[bool] = None
     show_pincount: Optional[bool] = None
     hide_disconnected_pins: bool = False
     autogenerate: bool = False
-    loops: List[Any] = field(default_factory=list)
+    loops: List[List[Pin]] = field(default_factory=list)
     ignore_in_bom: bool = False
     additional_components: List[AdditionalComponent] = field(default_factory=list)
 
@@ -155,23 +164,23 @@ def get_qty_multiplier(self, qty_multiplier: Optional[ConnectorMultiplier]) -> i
 
 @dataclass
 class Cable:
-    name: str
-    manufacturer: Optional[Union[str, List[str]]] = None
-    mpn: Optional[Union[str, List[str]]] = None
-    pn: Optional[Union[str, List[str]]] = None
+    name: Designator
+    manufacturer: Union[MLstr, List[MLstr], None] = None
+    mpn: Union[MLstr, List[MLstr], None] = None
+    pn: Union[str, List[str], None] = None
     category: Optional[str] = None
-    type: Optional[str] = None
+    type: Optional[MLstr] = None
     gauge: Optional[float] = None
     gauge_unit: Optional[str] = None
     show_equiv: bool = False
     length: float = 0
-    color: Optional[str] = None
+    color: Optional[Color] = None
     wirecount: Optional[int] = None
-    shield: Union[bool, str] = False # False | True | color
+    shield: Union[bool, Color] = False
     image: Optional[Image] = None
-    notes: Optional[str] = None
-    colors: List[Any] = field(default_factory=list)
-    color_code: Optional[str] = None
+    notes: Optional[MLstr] = None
+    colors: List[Colors] = field(default_factory=list)
+    color_code: Optional[ColorScheme] = None
     show_name: bool = True
     show_wirecount: bool = True
     ignore_in_bom: bool = False
@@ -264,8 +273,8 @@ def get_qty_multiplier(self, qty_multiplier: Optional[CableMultiplier]) -> float
 
 @dataclass
 class Connection:
-    from_name: Any
-    from_port: Any
-    via_port: Any
-    to_name: Any
-    to_port: Any
+    from_name: Optional[Designator]
+    from_port: Optional[Pin]
+    via_port: Wire
+    to_name: Optional[Designator]
+    to_port: Optional[Pin]