Class SystemPromptBuilder

tutorials/18_design_patterns_for_agents.py:397–467

Builder 模式三要素: 1. 字段全部可选 (None 默认值) 2. with_*() 方法返回 self (链式调用) 3. build() 方法组装最终结果

    # 对应 prompt.rs:85-93 的 SystemPromptBuilder
    @dataclass
    class SystemPromptBuilder:
        """
        Builder 模式三要素:
        1. 字段全部可选 (None 默认值)
        2. with_*() 方法返回 self (链式调用)
        3. build() 方法组装最终结果
        """
        # 所有字段可选 — 对应 prompt.rs:86-92 的 Option<String>
        _os_name: str | None = None
        _os_version: str | None = None
        _style_name: str | None = None
        _style_prompt: str | None = None
        _project_cwd: str | None = None
        _current_date: str | None = None
        _extra_sections: list[str] = field(default_factory=list)

        # 对应 prompt.rs:108-113
        # pub fn with_os(mut self, name, version) -> Self { ... self }
        def with_os(self, name: str, version: str) -> SystemPromptBuilder:
            self._os_name = name
            self._os_version = version
            return self  # 返回 self → 支持链式调用

        # 对应 prompt.rs:101-106
        def with_style(self, name: str, prompt: str) -> SystemPromptBuilder:
            self._style_name = name
            self._style_prompt = prompt
            return self

        def with_project(self, cwd: str, date: str) -> SystemPromptBuilder:
            self._project_cwd = cwd
            self._current_date = date
            return self

        # 对应 prompt.rs:128-131 的 append_section
        def append_section(self, section: str) -> SystemPromptBuilder:
            self._extra_sections.append(section)
            return self

        # 对应 prompt.rs:134-156 的 build()
        def build(self) -> list[str]:
            """组装最终的 system prompt 段落列表"""
            sections = []

            # 固定段落 (对应 get_simple_intro_section 等)
            sections.append("You are Claude, an AI assistant by Anthropic.")

            # 可选: 输出风格
            if self._style_name and self._style_prompt:
                sections.append(f"# Output Style: {self._style_name}\n{self._style_prompt}")

            sections.append("# System\n- Follow instructions carefully.")
            sections.append("# Doing tasks\n- Complete tasks step by step.")

            # 动态分界线 (对应 SYSTEM_PROMPT_DYNAMIC_BOUNDARY)
            # 分界线以上是静态内容 (API 缓存), 以下是动态内容 (每次不同)
            sections.append("__SYSTEM_PROMPT_DYNAMIC_BOUNDARY__")