editor - 如何理解这个vim脚本？

Question

以下是来自 vim 插件的 vim 脚本:
vim 的语法有点奇怪:

!exists("*s:SetVals") ，为什么他们之前是一个starmark s: ?

功能!，为什么会有!特点？

&iskeyword ，这是一个变量，如果是，它是在哪里定义的？

什么是s:和 g: ，它们之间有什么区别？

为什么要使用 let ？如 let &dictionary = g:pydiction_location ，我可以把它改成&dictionary = g:pydiction_location吗？ ?

if !exists("*s:SetVals")

  function! s:SetVals()
      " Save and change any config values we need.

      " Temporarily change isk to treat periods and opening 
      " parenthesis as part of a keyword -- so we can complete
      " python modules and functions:
      let s:pydiction_save_isk = &iskeyword
      setlocal iskeyword +=.,(

      " Save any current dictionaries the user has set:
      let s:pydiction_save_dictions = &dictionary
      " Temporarily use only pydiction's dictionary:
      let &dictionary = g:pydiction_location

      " Save the ins-completion options the user has set:
      let s:pydiction_save_cot = &completeopt
      " Have the completion menu show up for one or more matches:
      let &completeopt = "menu,menuone"

      " Set the popup menu height:
      let s:pydiction_save_pumheight = &pumheight
      if !exists('g:pydiction_menu_height')
          let g:pydiction_menu_height = 15
      endif
      let &pumheight = g:pydiction_menu_height

      return ''
  endfunction     

endif

Answer 1

1. !exists("*s:SetVals"), why their is a starmark before s:?

星号是exists 函数的特殊语法，它意味着我们正在检查是否存在名为SetVals 的现有函数。选项 iskeyword可以通过 exists("&iskeyword") 检查和 ex 命令 echo与 exists(":echo")
见 :h exists(

2. function!, why there is a ! character?

感叹号表示如果函数已经存在，则将被替换。

见 :h user-functions

3. &iskeyword, is this a variable, if yes, where it is defined?

那是一个 vim 选项。您可以检查它是否设置为 :set iskeyword?

4. what is s: and g:, what is the difference between them?

这些定义了以下符号的范围。 s:表示符号是脚本的本地符号，而 g:意味着符号将是全局的。

见 :h internal-variables和 s:见 :h script-variable

5. why let should be used? such as let &dictionary = g:pydiction_location, can i change it to be &dictionary = g:pydiction_location?

Vimscript 是一种需要用关键字声明变量的语言。我认为没有比 let 更容易声明变量的方法了。 .