Using Python in vimscript: How to export a value from a python script back to vim?

Question

I'm struggling with Python in vim.
I still haven't found out how I can import a value from a python script (in a vim function) back to vim p.e.

function! myvimscript()    python << endpython     import vim, random, sys     s = vim.eval("mylist")     # do operation with variable "s" in python   endpython    " import variable "s" from above    " do operation with "s" in vimscript endfunction 

1) How can I use "s" again in vim (how can I import "s" from the python code back to vim)?

I can't find out as well how to use vim.current.buffer with a selection.

function! myvimscript()   let startline = line("'<")   let endline = line("'>")    python << endpython     start = vim.eval("startline")     end = vim.eval("endline")     cb = vim.current.buffer      l = cb[start:end]   endpython endfunction 

2) How can I assign the dynamic value "start" and "end" to "l"

Answer 1

First of all, please define your function name starting with uppercase.

Here is an example for your two questions. I hope it helps:

function! TestPy() range      let startline = line("'<")     let endline = line("'>")     echo "vim-start:".startline . " vim-endline:".endline python << EOF import vim s = "I was set in python" vim.command("let sInVim = '%s'"% s) start = vim.eval("startline") end = vim.eval("endline") print "start, end in python:%s,%s"% (start, end) EOF     echo sInVim endfunction 

first I paste the output of a small test: I visual selected 3,4,5, three lines, and :call TestPy()

The output I had:

vim-start:3 vim-endline:5 start, end in python:3,5 I was set in python 

So I explain the output a bit, you may need to read the example function codes a little for understanding the comment below.

vim-start:3 vim-endline:5   #this line was printed in vim,  by vim's echo. start, end in python:3,5    # this line was prrinted in py, using the vim var startline and endline. this answered your question two. I was set in python         # this line was printed in vim, the variable value was set in python. it answered your question one. 

I added a range for your function. because, if you don't have it, for each visual-selected line, vim will call your function once. in my example, the function will be executed 3 times (3,4,5). with range, it will handle visualselection as a range. It is sufficient for this example. If your real function will do something else, you could remove the range.

With range, better with a:firstline and a:lastline. I used the line("'<") just for keep it same as your codes.

EDIT with list variable:

check this function:

function! TestPy2() python << EOF import vim s = range(10) vim.command("let sInVim = %s"% s) EOF     echo type(sInVim)     echo sInVim endfunction 

if you call it, the output is:

3 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] 

the "3" means type list (check type() function). and one line below is the string representation of list.

Answer 2

As of v7.3.569, vim built-in functions pyeval() and py3eval() allow you to evaluate a python expression, and return its result as a vimscript value. It can handle simple scalar values, but also lists and dictionaries - see :help pyeval()

On 1): For using a python-defined variable in vim:

python << endPython py_var = 8 endPython  let vim_var = pyeval('py_var') 

On 2): I assume you want the buffer lines last highlighted in visual mode, as a list of strings in vimscript:

python << endPython import vim cb = vim.current.buffer start = int(vim.eval("""line("'<")""")) end = int(vim.eval("""line("'>")""")) lines = cb[(start - 1) : end] endPython let lines = pyeval('lines') 

Note: This is a somewhat contrived example, as you could get the same directly in vimscript:

let lines = getline("'<", "'>")