解释Python编写vim插件
Vim 插件是一个 .vim 的脚本文件,定义了函数、映射、语法规则和命令,可用于操作窗口、缓冲以及行。一般一个插件包含了命令定义和事件钩子。当使用 Python 编写 vim 插件时,函数外面是使用 VimL 编写,尽管 VimL 学起来很快,但 Python 更加灵活,例如可以用 urllib/httplib/simplejson 来访问某些 Web 服务,这也是为什么很多需要访问 Web 服务的插件都是使用 VimL + Python 编写的原因。
在开始编写插件之前,你需要确认 Vim 支持 Python,通过以下命令来判别:
vim --version | grep +python
接下来我们通过一个简单的例子来学习用 Python 编写 Vim 插件,该插件用来获取 Reddit 首页信息并显示在当前缓冲区上。
首先在 Vim 新建 vimmit.vim 文件,我们首先需要判断是否支持 Python,如果不支持给出提示信息:
1 2 3 4 | if !has( ‘python‘ ) echo "Error: Required vim compiled with +python" finish endif |
上面这段代码就是用 VimL 编写的,它将检查 Vim 是否支持 Python。
下面是用 Python 编写的 Reddit() 主函数:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 | " Vim comments start with a double quote. " Function definition is VimL. We can mix VimL and Python in " function definition. function! Reddit() " We start the python code like the next line. python << EOF # the vim module contains everything we need to interface with vim from # python. We need urllib2 for the web service consumer. import vim, urllib2 # we need json for parsing the response import json # we define a timeout that we‘ll use in the API call. We don‘t want # users to wait much. TIMEOUT = 20 URL = "codego.net" try : # Get the posts and parse the json response response = urllib2.urlopen(URL, None , TIMEOUT).read() json_response = json.loads(response) posts = json_response.get( "data" , " ").get(" children ", " ") # vim.current.buffer is the current buffer. It‘s list-like object. # each line is an item in the list. We can loop through them delete # them, alter them etc. # Here we delete all lines in the current buffer del vim.current. buffer [:] # Here we append some lines above. Aesthetics. vim.current. buffer [ 0 ] = 80 * "-" for post in posts: # In the next few lines, we get the post details post_data = post.get( "data" , {}) up = post_data.get( "ups" , 0 ) down = post_data.get( "downs" , 0 ) title = post_data.get( "title" , "NO TITLE" ).encode( "utf-8" ) score = post_data.get( "score" , 0 ) permalink = post_data.get( "permalink" ).encode( "utf-8" ) url = post_data.get( "url" ).encode( "utf-8" ) comments = post_data.get( "num_comments" ) # And here we append line by line to the buffer. # First the upvotes vim.current. buffer .append( "↑ %s" % up) # Then the title and the url vim.current. buffer .append( " %s [%s]" % (title, url,)) # Then the downvotes and number of comments vim.current. buffer .append( "↓ %s | comments: %s [%s]" % (down, comments, permalink,)) # And last we append some "-" for visual appeal. vim.current. buffer .append( 80 * "-" ) except Exception, e: print e EOF " Here the python code is closed. We can continue writing VimL or python again. endfunction |
使用如下命令保存文件
:source vimmit.vim
然后调用该插件:
:call Reddit()
这个命令用起来不那么方便,因此我们再定义一个命令:
command! -nargs=0 Reddit call Reddit()
我们定义了命令:Reddit来调用这个函数。-nargs 参数声明命令行中有多少个参数。
关于函数参数的问题:
问:如何访问函数中的参数?
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | function! SomeName(arg1, arg2, arg3) " Get the first argument by name in VimL let firstarg = a:arg1 " Get the second argument by position in Viml let secondarg = a: 1 " Get the arguments in python python << EOF import vim first_argument = vim. eval ( "a:arg1" ) #or vim.eval("a:0") second_argument = vim. eval ( "a:arg2" ) #or vim.eval("a:1") |
你可以使用 ... 来处理可变个数参数来替换特定的参数名,可通过位置或者命名参数来访问,如:(arg1, arg2, ...)
问:如何在 Python 中调用 Vim 命令?
vim.command("[vim-command-here]")
问:如何定义全局变量,并在 VimL 和 Python 中访问?
全局变量使用形如 g:. 的前缀,定义全局变量前应该检查该变量是否已定义:
1 2 3 | if !exists( "g:reddit_apicall_timeout" ) let g:reddit_apicall_timeout = 40 endif |
然后你通过下面代码在 Python 中访问这个变量:
1 | TIMEOUT = vim. eval ( "g:reddit_apicall_timeout" ) |
可通过下面的方法来对全局变量进行重新赋值:
1 | let g:reddit_apicall_timeout = 60 |
更多关于使用 Python 编写 Vim 插件的说明请看官方文档。
codego.net代码节选
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