✨ support user-defined format spec for message template

nonebot/adapters/_template.py

@@ -4,6 +4,9 @@ from string import Formatter
 from typing import (
     TYPE_CHECKING,
     Any,
+    Callable,
+    Dict,
+    Optional,
     Set,
     List,
     Type,
@@ -23,6 +26,9 @@ if TYPE_CHECKING:
 TM = TypeVar("TM", bound="Message")
 TF = TypeVar("TF", str, "Message")
 
+FormatSpecFunc = Callable[[Any], str]
+FormatSpecFunc_T = TypeVar("FormatSpecFunc_T", bound=FormatSpecFunc)
+
 
 class MessageTemplate(Formatter, Generic[TF]):
     """消息模板格式化实现类"""
@@ -50,8 +56,18 @@ class MessageTemplate(Formatter, Generic[TF]):
           * ``template: Union[str, Message]``: 模板
           * ``factory: Union[str, Message]``: 消息构造类型，默认为 `str`
         """
-        self.template: Union[str, TF] = template
+        self.template: TF = template
         self.factory: Type[TF] = factory
+        self.format_specs: Dict[str, FormatSpecFunc] = {}
+
+    def add_format_spec(
+        self, spec: FormatSpecFunc_T, name: Optional[str] = None
+    ) -> FormatSpecFunc_T:
+        name = name or spec.__name__
+        if name in self.format_specs:
+            raise ValueError(f"Format spec {name} already exists!")
+        self.format_specs[name] = spec
+        return spec
 
     def format(self, *args: Any, **kwargs: Any) -> TF:
         """
@@ -69,7 +85,7 @@ class MessageTemplate(Formatter, Generic[TF]):
         else:
             raise TypeError("template must be a string or instance of Message!")
 
-        return msg
+        return msg  # type:ignore
 
     def vformat(
         self, format_string: str, args: Sequence[Any], kwargs: Mapping[str, Any]
@@ -165,13 +181,15 @@ class MessageTemplate(Formatter, Generic[TF]):
             (
                 super().format_field(value, format_spec)
                 if (
-                    (method is None)
-                    or (
-                        not isinstance(method_type, (classmethod, staticmethod))
-                    )  # Only Call staticmethod or classmethod
+                    method is None
+                    or not isinstance(method_type, (classmethod, staticmethod))
                 )
+                else (
+                    self.format_specs[format_spec](value)
+                    if format_spec in self.format_specs
                     else method(value)
                 )
+            )
             if format_spec
             else value
         )