✨ support use Message object as message template

nonebot/adapters/_message.py

@@ -103,11 +103,12 @@ class Message(List[TMS], abc.ABC):
             self.extend(self._construct(message))
 
     @classmethod
-    def template(cls: Type[TM], format_string: str) -> MessageTemplate[TM]:
+    def template(cls: Type[TM],
+                 format_string: Union[str, TM]) -> MessageTemplate[TM]:
         """
         :说明:
 
-          根据创建消息模板, 用法和 ``str.format`` 大致相同, 但是可以输出消息对象
+          根据创建消息模板, 用法和 ``str.format`` 大致相同, 但是可以输出消息对象, 并且支持以 ``Message`` 对象作为消息模板
 
         :示例:
 
@@ -117,6 +118,13 @@ class Message(List[TMS], abc.ABC):
             Message(MessageSegment(type='text', data={'text': 'hello world'}))
             >>> Message.template("{} {}").format(MessageSegment.image("file///..."), "world")
             Message(MessageSegment(type='image', data={'file': 'file///...'}), MessageSegment(type='text', data={'text': 'world'}))
+            >>> Message.template(
+            ...       MessageSegment.text('test {event.user_id}') + MessageSegment.face(233) +
+            ...       MessageSegment.text('test {event.message}')).format(event={'user_id':123456, 'message':'hello world'}
+            ... )
+            Message(MessageSegment(type='text', data={'text': 'test 123456'}), 
+                    MessageSegment(type='face', data={'face': 233}), 
+                    MessageSegment(type='text', data={'text': 'test hello world'}))
 
         :参数:
 

nonebot/adapters/_template.py

@@ -1,11 +1,10 @@
-import operator
 import functools
 from string import Formatter
 from typing import (TYPE_CHECKING, Any, Set, List, Type, Tuple, Union, Generic,
                     Mapping, TypeVar, Sequence)
 
 if TYPE_CHECKING:
-    from . import Message
+    from . import Message, MessageSegment
 
 TM = TypeVar("TM", bound="Message")
 
@@ -13,7 +12,7 @@ TM = TypeVar("TM", bound="Message")
 class MessageTemplate(Formatter, Generic[TM]):
     """消息模板格式化实现类"""
 
-    def __init__(self, factory: Type[TM], template: str) -> None:
+    def __init__(self, factory: Type[TM], template: Union[str, TM]) -> None:
         self.template = template
         self.factory = factory
 
@@ -23,8 +22,18 @@ class MessageTemplate(Formatter, Generic[TM]):
 
           根据模板和参数生成消息对象
         """
-        msg = self.vformat(self.template, args, kwargs)
-        return msg if isinstance(msg, self.factory) else self.factory(msg)
+        msg = self.factory()
+        if isinstance(self.template, str):
+            msg += self.vformat(self.template, args, kwargs)
+        elif isinstance(self.template, self.factory):
+            for seg in self.template:
+                seg: "MessageSegment"
+                msg += self.vformat(str(seg), args,
+                                    kwargs) if seg.is_text() else seg
+        else:
+            raise TypeError('template must be a string or instance of Message!')
+
+        return msg
 
     def vformat(self, format_string: str, args: Sequence[Any],
                 kwargs: Mapping[str, Any]) -> TM:
@@ -101,9 +110,15 @@ class MessageTemplate(Formatter, Generic[TM]):
                 formatted_text = self.format_field(obj, str(format_control))
                 results.append(formatted_text)
 
-        return self.factory(functools.reduce(operator.add, results or
+        return self.factory(functools.reduce(self._add, results or
                                              [""])), auto_arg_index
 
     def format_field(self, value: Any, format_spec: str) -> Any:
         return super().format_field(value,
                                     format_spec) if format_spec else value
+
+    def _add(self, a: Any, b: Any) -> Any:
+        try:
+            return a + b
+        except TypeError:
+            return a + str(b)