feat: nix module's default parameters & specialArgs

docs/nixos-with-flakes/nixos-with-flakes-enabled.md

@@ -125,7 +125,7 @@ Note that the copied template cannot be used directly. You need to modify it to
         #
         # A Nix Module can be an attribute set, or a function that
         # returns an attribute set. By default, if a Nix Module is a
-        # function, this function can only have the following parameters:
+        # function, this function have the following default parameters:
         #
         #  lib:     the nixpkgs function library, which provides many
         #             useful functions for operating Nix expressions:
@@ -143,11 +143,12 @@ Note that the copied template cannot be used directly. You need to modify it to
         #               this parameter is rarely used,
         #               you can ignore it for now.
         #
-        # Only these parameters can be passed by default.
-        # If you need to pass other parameters,
+        # The default parameters mentioned above are automatically generated by Nixpkgs. 
+        # However, if you need to pass other non-default parameters to the submodules, 
+        # you'll have to manually configure these parameters using `specialArgs`. 
         # you must use `specialArgs` by uncomment the following line:
         #
-        # specialArgs = {...}  # pass custom arguments into all sub module.
+        # specialArgs = {...};  # pass custom arguments into all sub module.
         modules = [
           # Import the configuration.nix here, so that the
           # old configuration file can still take effect.
@@ -164,6 +165,14 @@ We defined a NixOS system called `nixos-test` with a configuration file at `./co
 
 To apply the configuration to a system with hostname `nixos-test`, run `sudo nixos-rebuild switch --flake /etc/nixos#nixos-test`. No changes will be made to the system because we imported the old configuration file in `/etc/nixos/flake.nix`, so the actual state we declared remains unchanged.
 
+The comments in the above code are already quite detailed, but let's emphasize a few points here:
+
+1. Default parameters like `lib`, `pkgs`, `config`, and others are automatically generated by Nixpkgs and can be automatically injected into submodules without the need for additional declarations here.
+
+2. In `specialArgs = {...};`, the content of the attribute set is omitted here. Its contents are automatically injected into submodules through name matching.
+   
+   1. A common usage, for instance, is to directly write `specialArgs = inputs;`, enabling all data sources from the `inputs` attribute set to be used in the submodules.
+
 ## Managing System Packages with Flakes
 
 After the switch, we can manage the system using Flakes. One common requirement is installing packages. We have previously seen how to install packages using `environment.systemPackages` from the official `nixpkgs` repository.

docs/zh/nixos-with-flakes/nixos-with-flakes-enabled.md

@@ -118,7 +118,7 @@ cat flake.nix
         # 那么它的参数就是当前的 NixOS Module 的参数.
         #
         # 根据 Nix Wiki 对 Nix modules 的描述，默认情况下，
-        # Nix Module 函数的参数可以有这几个：
+        # Nix Module 函数的默认参数有几个：
         #
         #  lib:     nixpkgs 自带的函数库，提供了许多操作 Nix 表达式的实用函数
         #           详见 https://nixos.org/manual/nixpkgs/stable/#id-1.4
@@ -131,8 +131,10 @@ cat flake.nix
         #               常用于从 nixpkgs 中导入一些额外的模块
         #               这个参数通常都用不到，我只在制作 iso 镜像时用到过
         #
-        # 如果需要传其他非默认参数，就得使用 specialArgs，你可以取消注释如下这行来启用该参数
-        # specialArgs = inputs  # 将 inputs 中的参数传入所有子模块
+        # 上述默认参数都由 Nixpkgs 自动生成。而如果你需要将其他非默认参数传递到子模块，
+        # 就得使用 specialArgs 手动设定这些参数，你可以取消注释如下这行来启用该参数：
+        #
+        # specialArgs = {...};  # 将 inputs 中的参数传入所有子模块
         modules = [
           # 这里导入之前我们使用的 configuration.nix，这样旧的配置文件仍然能生效
           # 注: configuration.nix 本身也是一个 Nix Module，因此可以直接在这里导入
@@ -148,6 +150,12 @@ cat flake.nix
 
 现在执行 `sudo nixos-rebuild switch --flake /etc/nixos#nixos-test` 应用配置，系统应该没有任何变化，因为我们仅仅是切换到了 Nix Flakes，配置内容与之前还是一致的。
 
+上述代码的注释已经非常详细了，这里再着重说明几点： 
+
+1. `lib` `pkgs` `config` 等默认参数都由 Nixpkgs 自动生成，并可被自动注入到子模块，无需在此处额外声明。
+1. `specialArgs = {...};` 这里省略了 attribute set 的内容，其中的内容会被通过名称匹配的方式自动注入到子模块中。
+    1. 常见用法比如直接写 `specialArgs = inputs;`，这样所有 inputs 中的 flake 数据源就都可以在子模块中使用了。
+
 ## 通过 Flakes 来管理系统软件 {#manage-system-software-with-flakes}
 
 切换完毕后，我们就可以通过 Flakes 来管理系统了。管系统最常见的需求就是装软件，我们在前面已经见识过如何通过 `environment.systemPackages` 来安装 `pkgs` 中的包，这些包都来自官方的 nixpkgs 仓库。