A simple example of writing the vim plug-in using Python

This article mainly introduces a simple tutorial on compiling the vim plug-in using Python. An example of getting the reddit homepage information and displaying it in the buffer zone is provided in this article. For more information, see the Vim plug-in. the vim script file defines functions, ING, syntax rules, and commands, which can be used for Operation windows, buffering, and rows. Generally, a plug-in contains command definitions and event hooks. When using Python to compile the vim plug-in, the function is written outside VimL. although VimL is fast to learn, Python is more flexible. for example, you can use urllib/httplib/simplejson to access some Web services, this is why many plug-ins that need to access Web services are written using VimL + Python.

Before writing the plug-in, you must confirm that Vim supports Python and use the following command to determine whether the plug-in is supported:

The code is as follows:

Vim -- version | grep + python

Next, we will use a simple example to learn how to compile the Vim plug-in Python. this plug-in is used to obtain the Reddit homepage information and display it on the current buffer.

First, create a vimmit. Vim file in vim. First, we need to determine whether Python is supported. if not, the following message is displayed:

if !has('python')  echo "Error: Required vim compiled with +python"  finishendif

The above code is written in VimL. it will check whether Vim supports Python.

The main function of Reddit () written in Python is as follows:

" 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 responseimport json # we define a timeout that we'll use in the API call. We don't want# users to wait much.TIMEOUT = 20URL = "http://reddit.com/.json" 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

Run the following command to save the file:

The code is as follows:

: Source vimmit. vim

Then call the plug-in:

The code is as follows:

: Call Reddit ()

This command is not easy to use, so we define another command:

The code is as follows:

Command! -Nargs = 0 Reddit call Reddit ()

We defined the command: Reddit to call this function. -The nargs parameter declares the number of parameters in the command line.

Questions about function parameters:

Q: How do I access parameters in a function?

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")

You can use a variable number parameter to replace a specific parameter name, which can be accessed by location or named parameter, such as: (arg1, arg2 ,...)

Q: How to call the Vim command in Python?

The code is as follows:

Vim. command ("[vim-command-here]")

Q: How do I define global variables and access them in VimL and Python?

The global variable uses a prefix such as g:. before defining a global variable, check whether the variable has been defined:

if !exists("g:reddit_apicall_timeout")  let g:reddit_apicall_timeout=40endif

Then you can access this variable in Python using the following code:

TIMEOUT = vim.eval("g:reddit_apicall_timeout")

You can assign a value to a global variable using the following method:

let g:reddit_apicall_timeout=60