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Embedding executable python script in python string

If you are a bash/posix sh wizard you will know the $(command substition) feature in bash, which could even be inserted in a string. For example,
$ echo "I can count: $(seq 1 10 | tr -d '\n')"
I can count: 12345678910
You can imagine all wild things to do with this, especially to make a dynamically formed string. No need to do if..else block outside the string; just embed the code inside! I am s spoiled by this feature. So here's the question: in python, can we do something similar? Is there one person already devising a module to accomplish this task?
(Just a side comment: admittedly having this kind of feature is powerful but also opening yourself to a security risk. The program can be vulnerable to code injection. So think thoroughly before doing this especially with a foreign string coming from outside the code.)

You can use eval() and all of it's potential risks...
Some good links here and here

See the built-in eval() function.

Are you looking for an fstring:
Instead of starting the string with '
We start the string with f'
And whenever we want to embed any script we just put inside these: {}

vimrc mapping problem; execute python script mapping not working from vimrc

grr. I'm struggling with Vim's learning curve.
And trying to get a simple mapping in my vimrc to execute the current buffer's python script.
The mapping is well-formed and works after I enter it into the command line in Vim. This is the mapping:
map <buffer> <S-e> :w<CR>:!usr/bin/env python % <CR>
But it won't load from my vimrc :( I'm using the basic .vimrc_sample with only this mapping appended. What's weird is that I could get a different mapping working from the vimrc:
map <S-t> itest<Esc>
This one works, but not the script executer? What gives?
Ubuntu 10.10 Python 2.6 Vim 7.2
Help is very appreciated!

I suspect that you have something before map: <buffer> argument means that mapping is defined for current buffer only, so adding it to vimrc without something like autocmd FileType python before it is weird. Maybe it is the reason why it does not work: you somehow switch to another buffer before testing this mapping.
Some additional things to concern:
Never use map where can use noremap instead.
You probably don't want this mapping to be defined for visual (at least without <C-u> before w) and select modes, and definitely don't want it to be defined for operator-pending modes, so use nnoremap.
<S-e> and E are equivalent.
You can combine w and !... in one command using pipe symbol: :w | !/usr/bin/env python %<CR>.
You forgot slash before usr.

Jesus, Murphy's Law.
After searching for an answer for an hour, 1 min after posting this q I solved it. The problem was <buffer> in the mapping.
Removing it made the mapping work, thus:
nnoremap E w:<CR>:!python % <CR>

How do you enable block folding for Python comments in TextMate?

In TextMate 1.5.10 r1623, you get little arrows that allow you to fold method blocks:
Unfortunately, if you have a multi-lined Python comment, it doesn't recognize it, so you can't fold it:
def foo():
"""
How do
I fold
these comments?
"""
print "bar"
TextMate has this on their site on how to customize folding: http://manual.macromates.com/en/navigation_overview#customizing_foldings
...but I'm not skilled in regex enough to do anything about it. TextMate uses the Oniguruma regex API, and I'm using the default Python.tmbundle updated to the newest version via GetBundles.
Does anyone have an idea of how to do this? Thanks in advance for your help! :)
Adding the default foldingStartMarker and foldingStopMarker regex values for Python.tmbundle under the Python Language in Bundle Editor:
foldingStartMarker = '^\s*(def|class)\s+([.a-zA-Z0-9_ <]+)\s*(\((.*)\))?\s*:|\{\s*$|\(\s*$|\[\s*$|^\s*"""(?=.)(?!.*""")';
foldingStopMarker = '^\s*$|^\s*\}|^\s*\]|^\s*\)|^\s*"""\s*$';

It appears that multi-line comment folding does work in TextMate, but your must line up your quotes exactly like so:
""" Some sort of multi
line comment, which needs quotes
in just the right places to work. """
That seems to do it:

According to this Textmate Mailing list thread, if you follow it to the end, proper code folding for Python is not supported. Basically, regular expressions as implemented in the foldingStartMarker and foldingStopMarker do not allow for captures, thus the amount of spacing at the beginning of the "end fold" cannot be matched to the "begin fold".
The issue is not finally and officially addressed by Textmate's creator, Allan Odgaard; however since the thread is from 2005, I assume it is a dead issue, and not one that will be supported.

How to fold long docstrings in python source code in VIM?

Does anybody know of a method, or perhaps a plugin, that will
automatically fold long docstrings in Python? I have docstrings in my
code that span several pages, so it is troublesome to keep paging
through them. The other tricky part is that there is embedded python
testing code in the docstrings, so that might make parsing them
difficult. Note that I only need to automatically fold the entire
docstring, regardless of what is in it.

This is a bit of a dirty hack, but you can go through the python syntax file (:sp $VIMRUNTIME/syntax/python.vim) and find all the syntax regions for triple-quoted strings (search for ''' and """) and add the fold keyword to the end of those statements. Then just set foldmethod=syntax for python files and the comments should be folded.

I'm not sure about a plugin or automation, but if you type zf/ you can then search for something and it will fold up to the next instance of it. So in a document like the following (where [] is the cursor):
def foo():
"""[]
Some long docstring
that takes up many
lines
"""
pass
Look at edit2 first for the updated search string!
If you use the command zf/"""[ENTER], it should fold everything from the current line (the beginning of the docstring) to the next occurrence of """ which should be the end of the docstring.
I know this isn't automation, but perhaps it will help in the interim, or lead you down the right path to automating it. See edit2 for a better search function, although I still don't know how to automate.
Hope this helps.
Edit: in a corollary, you can search for any docstring with /"""\_.\{-}""", although this will also return the code within the docstring. To search for a function definition followed by a docstring, you can use /def\_.\{-}"""\_.\{-}""", although this breaks on a def inside the docstring.
Edit2: Actually, some more playing with regexs led me to this: /def.\{-}):\_s*"""\_.\{-}""" which should find any function followed by a docstring. It searches for def followed by any characters, then ): followed by a newline and/or whitespace followed by """ followed by any number of lines than the next """, but always ensures the 2nd triple quote is the one immediately following the first.

In your .vimrc add:
" folding
set foldmethod=indent
This will auto-fold at every indentation, which, in python, translates to docstrings. It works VERY VERY nice. Give it a try. The above answer is correct, but requires a bunch of keystrokes (blah!)

I think I've found a slight improvement to the answer of #too_much_php by trying to figure out how to do the same thing without root access. Copying the syntax region definitions from $VIMRUNTIME/syntax/python.vim to ~/.vim/after/syntax/python.vim and editing them solved the problem for me. Here's my code for ~/.vim/after/syntax/python.vim:
syn region docString1
\ start=+[uU]\=\z('''\|"""\)+ end="\z1" keepend transparent fold
syn region docString2
\ start=+[uU]\=[rR]\z('''\|"""\)+ end="\z1" keepend transparent fold
Now I can run :set foldmethod=syntax to fold docstrings.
PS: Credits to #too_much_php for the initial idea

You can do this with :set foldmethod=marker foldmarker=""",""", I think. I haven't tested it, but that should do the trick. The arguments to foldmarker are start and end markers.

I wrote a vimscript plugin many years ago to do exactly this, but never got around to publishing it. I've put it up as a gist, but have also pasted the source below. I've also replicated its functionality for Sublime Text here.
"
" Fold multi-line Python comments into one line.
"
" Also maps the "-" key to toggle expansion and <C-f> to toggle all folding.
"
setlocal foldmethod=syntax
setlocal foldtext=FoldText()
setlocal fillchars=
map <buffer> - za
map <buffer> <C-f> :call ToggleFold()<CR>
let b:folded = 1
hi Folded gui=bold cterm=bold guifg=cyan ctermfg=cyan guibg=NONE ctermbg=NONE
function! ToggleFold()
if b:folded == 0
exec "normal! zM"
let b:folded = 1
else
exec "normal! zR"
let b:folded = 0
endif
endfunction
function! s:Strip(string)
return substitute(a:string, '^[[:space:][:return:][:cntrl:]]\+\|[[:space:][:return:][:cntrl:]]\+$', '', '')
endfunction
" Extract the first line of a multi-line comment to use as the fold snippet
function! FoldText()
let l:snippet = getline(v:foldstart)
if len(s:Strip(l:snippet)) == 3
let l:snippet = strpart(l:snippet, 1) . s:Strip(getline(v:foldstart + 1))
endif
return '+' . l:snippet . ' ...'
endfunction

My solution involves using SimpylFold. After installing it using Vundle, I put this in my vimrc file:
autocmd FileType python setlocal foldlevel=2
Which makes all docstrings folded by default when you open a python file, which is super awesome.

Reverse a word in Vim

How can I reverse a word in Vim? Preferably with a regex or normal-mode commands, but other methods are welcome too:
word => drow
Thanks for your help!
PS: I'm in windows XP
Python is built in supported in my vim, but not Perl.

Here is another (pythonic) solution based on how this works:
:echo join(reverse(split('hello', '.\zs')), '')
olleh
If you want to replace all words in the buffer,
:%s/\(\<.\{-}\>\)/\=join(reverse(split(submatch(1), '.\zs')), '')/g
This works by first creating a list of characters in the word, which is reversed and joined back to form the word. The substitute command finds each word and then passes the word to the expressions and uses the result as replacement.

This Tip might help: http://vim.wikia.com/wiki/Reverse_letters
It says:
Simply enable visual mode (v), highlight the characters you want inverted, and hit \is. For a single word you can use vw (or viw): viw\is
vnoremap <silent> <Leader>is :<C-U>let old_reg_a=#a<CR>
\:let old_reg=#"<CR>
\gv"ay
\:let #a=substitute(#a, '.\(.*\)\#=',
\ '\=#a[strlen(submatch(1))]', 'g')<CR>
\gvc<C-R>a<Esc>
\:let #a=old_reg_a<CR>
\:let #"=old_reg<CR>
There are more solutions in the comments.

Assuming you've got perl support built in to vim, you can do this:
command! ReverseWord call ReverseWord()
function! ReverseWord()
perl << EOF
$curword = VIM::Eval('expand("<cword>")');
$reversed = reverse($curword);
VIM::Msg("$curword => $reversed");
VIM::DoCommand("norm lbcw$reversed");
EOF
endfun
And potentially bind that to a keystroke like so:
nmap ,r :ReverseWord<CR>

I don't have Python supported on my VIM, but it looks like it would be pretty simple to do it with Python. This article seems like a good explanation of how to use Python in VIM and I'm guessing you'd do something like this:
:python 'word'[::-1]
The article indicates that the result will appear in the status bar, which would be non-optimal if you were trying to replace the string in a document, but if you just want to check that your girlfriend is properly reversing strings in her head, this should be fine.

If you have rev installed (e.g. via MSys or Cygwin) then it's really not this difficult.
Select what you want to reverse and filter (%! <cmd>) it:
:%! rev
This pipes your selection to your shell while passing it a command.

if your version of VIM supports it you can do vw\is or viw\is (put your cursor at the first letter of the word before typing the command)... but I have had a lot of compatibility issues with that. Not sure what has to be compiled in or turned on but this only works sometimes.
EDIT:
\is is:
:<C-U>let old_reg_a=#a<CR>
\ :let old_reg=#"<CR>
\ gv"ay :let #a=substitute(#a, '.\(.*\)\#=', '\=#a[strlen(submatch(1))]', 'g')<CR>
\ gvc<C-R>a<Esc> :let #a=old_reg_a<CR>
\ :let #"=old_reg<CR>
Didn't remember where it came from but a google search come this article on vim.wikia.com. Which shows the same thing so I guess that's it.

Well you could use python itself to reverse the line through the filter command. Say the text you had written was:
Python
You could reverse it by issuing.
:1 ! python -c "print raw_input()[::-1]"
And your text will be replaced to become:
nohtyP
The "1" in the command tells vi to send line 1 to the python statement which we are executing: "print raw_input()[::-1]". So if you wanted some other line reversed, you would send that line number as argument. The python statement then reverses the line of input.

There is a tricky way to do this if you have Vim compiled with +rightleft. You set 'allowrevins' which let you hit Ctrl+_ in insert mode to start Reverse Insert mode. It was originally made for inserting bidirectional scripts.
Type your desired word in Insert mode, or move your cursor to the end of an already typed word. Hit Ctrl+_ and then pick a completion (i_Ctrl-x) method which is the most likely not to return any results for your word. Ysing Ctrl+e to cancel in-place completion does not seem to work in this case.
I.e. for an unsyntactic text file you can hit in insert mode Ctrl+x Ctrl+d which is guaranteed to fail to find any macro/function names in the current file (See :h i_CTRL-X_CTRL-D and:h complete for more information).
And voila! Completion lookup in reverse mode makes the looked up word reverse. Notice that the cursor will move to the beginning of that word (it's reversed direction of writing, remember?)
You should then hit Ctrl+_ again to get back to regular insert mode and keyboard layout and go on with editing.
Tip: You can set 'complete' exclusively (for the buffer, at least) to a completion option that is guaranteed to return no result. Just go over the options in :h 'complete'. This will make the easy i_Ctrl-N / i_Ctrl-P bindings available for a handy word reversal session. You can ofcourse further automate this with a macro, a function or a binding
Note: Setting/resetting 'paste' and 'compatible' can set/reset 'allowrevins'. See :h allowrevins.

If you have some time on your hands, you can bubble your way there by iteratively transposing characters (xp)...

I realize I'm a little late to the game, but I thought I'd just add what I think is the simplest method.
It's two things:
Vim's expression register
pyeval (py3eval on recent vim releases) function
So to reverse a word you would do the following:
"ayiw yank word into register a
<C-r>=py3eval('"".join(reversed(str(' . #a ')))') use vim's = (expression) register to call the py3eval function which evaluates python code (duh) and returns the result, which is then fed via the expression register into our document.
For more info on the expression register see https://www.brianstorti.com/vim-registers/#the-expression-and-the-search-registers

you can use revins mode in order to do it:
at the beginning type :set revins. from now on every letter you type will be inserted in a reverse order, until you type :set norevins to turn off. i.e, while revins is set, typing word will output drow.
in order to change an existing word after revins mode is set, and the cursor on beginning of the word, type:
dwi<C-r>"<ESC>
explanation:
dw deleted a word.
i to enter insert mode
<C-r>" to paste the last deleted or yaked text in insert mode, <ESC> to exit insert mode.
remember to :set norevins at the end!