Nico Brailovsky's thought repository

Posts for 2016 November

Simple vim plugin III: a polymorphic project greper

Post by Nico Brailovsky @ 2016-11-30 | Permalink | Leave a comment

We've recently seen a very basic function to integrate grep to vim. We can improve it a little bit with very simple changes. Using this tip to have different key binding for different modes we can do something a bit smarter . Let's create two functions, one for normal mode that should prompt the user what to search for, and another function to automagically pick whatever is selected:

function! FG_DoSearch(needle)
    let grepbin = 'grep -nri '
    tabnew
    setlocal buftype=nofile bufhidden=wipe nobuflisted noswapfile nowrap
    let cmd = grepbin . ' "' . a:needle . '" *'
    execute '$read !' . cmd
    setlocal nomodifiable
endfunction
function! FG_Search()
    let needle = input("Search for: ")
    call FG_DoSearch(needle)
endfunction
function! FG_Visual_Search()
    " Copy whatever is selected in visual mode
    try
        silent! let a_save = @a
        silent! normal! gv"ay
        silent! let needle = @a
    finally
        silent! let @a = a_save
    endtry
    call FG_DoSearch(needle)
endfunction
nmap s :call FG_Search()
vmap s :call FG_Visual_Search()

The magic here happens in the mapping: nmap will create a mapping that's only enabled when on "normal" mode, vmap when you're in visual mode. As usual, check :help map for more details.

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Simple vim plugin II: a psychic project greper

Post by Nico Brailovsky @ 2016-11-29 | Permalink | Leave a comment

We have been working on a quick grep integration for Vim, and it's looking decent enough for a quick plugin. There's one more easy thing we can improve, though: let's make it psychic! So far we had to tell grep what to look for, either by selecting the text in visual mode or by actually typing the search terms. Typing! That's so old fashioned. Let's make grep guess what to look for.

In vim you have a psychic function, expand(""). If you call expand(""), it will return whatever word is under the cursor. No need to visually select it. If you're still using the same vimrc definitions, you can do something like

nmap s :call FG95DoSearch(expand(""))

Let's clean things up a little bit:

" Wrap a grep command: search for needle, show results in a new window
function! FG_DoSearch(needle)
    let grepbin = 'grep -nri '
    tabnew
    setlocal buftype=nofile bufhidden=wipe nobuflisted noswapfile nowrap
    let cmd = grepbin . ' "' . a:needle . '" *'
    echom cmd
    execute '$read !' . cmd
    setlocal nomodifiable
endfunction
" Wrap a normal action: ask the user for input, then call func with it
function! FG_RequestInputAction(msg, func)
    let needle = input(a:msg)
    if strlen(needle) > 0
        execute 'call' a:func .'("'. needle . '")'
    endif
endfunction
" Wrap a visual action: call func with whatever is selected under the cursor
function! FG_VAction(func)
    " Copy whatever is selected in visual mode
    try
        silent! let a_save = @a
        silent! normal! gv"ay
        silent! let needle = @a
    finally
        silent! let @a = a_save
    endtry
    " Remove whitespaces
    let needle = substitute(needle, "92n92+","","g")
    let needle = substitute(needle, "92r92+","","g")
    let needle = substitute(needle, "^92s92+92|92s92+$","","g")
    if strlen(needle) > 0
        execute 'call' a:func .'("'. needle . '")'
    endif
endfunction
" Wrap a normal action: call func with whatever is under the cursor
function! FG_NAction(func)
    let needle = expand("")
    if strlen(needle) > 0
        execute 'call' a:func .'("'. needle . '")'
    endif
endfunction
nmap s :call FG_NAction("FG_DoSearchText")
vmap s :call FG_VAction("FG_DoSearchText")
map  S :call FG_RequestInputAction("Text search: ", "FG_DoSearchText")

Just copy paste that in your vimrc, now you can grep your project in three different ways: press s (,s) to look for the word currently under the cursor, S to type in a search term or select something in visual mode, then S to grep it.

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Simple vim plugin I: integrating new commands

Post by Nico Brailovsky @ 2016-11-24 | Permalink | Leave a comment

TL;DR: Here's some code to integrate system commands into vim. You can just drop it in your vimrc, create a small wrapper function in your vimrc and configure a few key binding to make it work.

Longer version: We can extend our quick grep integration to other commands, quite easily. Since we defined a few wrappers to request input, get it from visual mode or just guess it, we can also have a helper function to create a scratch buffer and read a system command into it:

" Find&Grep command wrapper: execute cmd, shows the results in a scratch buffer
function! FG_EvalSysCmdInNewBuff(cmd)
    tabnew
    setlocal buftype=nofile bufhidden=wipe nobuflisted noswapfile nowrap
    execute '$read !' . a:cmd
    setlocal nomodifiable
endfunction
" Wrap a normal action: ask the user for input, then call func with it
function! FG_RequestInputAction(msg, func)
    let needle = input(a:msg)
    if strlen(needle) > 0
        execute 'call' a:func .'("'. needle . '")'
    endif
endfunction
" Wrap a visual action: call func with whatever is selected under the cursor
function! FG_VAction(func)
    " Copy whatever is selected in visual mode
    try
        silent! let a_save = @a
        silent! normal! gv"ay
        silent! let needle = @a
    finally
        silent! let @a = a_save
    endtry
    " Remove whitespaces
    let needle = substitute(needle, "92n92+","","g")
    let needle = substitute(needle, "92r92+","","g")
    let needle = substitute(needle, "^92s92+92|92s92+$","","g")
    if strlen(needle) > 0
        execute 'call' a:func .'("'. needle . '")'
    endif
endfunction
" Wrap a normal action: call func with whatever is under the cursor
function! FG_NAction(func)
    let needle = expand("")
    if strlen(needle) > 0
        execute 'call' a:func .'("'. needle . '")'
    endif
endfunction

Integrating any new command into our plugin is now trivial. Let's do it for grep and for find:

" Wrap a find command: search for file "needle", show results in a new window
function! FG_DoFindFile(needle)
    let cmd = 'find -type f -iname "' . a:needle . '"'
    call FG_EvalSysCmdInNewBuff(cmd)
endfunction
" Wrap a grep command: search for needle, show results in a new window
function! FG_DoSearchText(needle)
    let cmd = 'grep -nri "' . a:needle . '" *'
    call FG_EvalSysCmdInNewBuff(cmd)
endfunction

Then just add a few key bindings and you're good to go:

gt;f :call FG_NAction("FG_DoFindFile")
vmap f :call FG_VAction("FG_DoFindFile")
map  S :call FG_RequestInputAction("Text search: ", "FG_DoSearchText")
nmap s :call FG_NAction("FG_DoSearchText")
vmap s :call FG_VAction("FG_DoSearchText")
map  F :call FG_RequestInputAction("Find file: ", "FG_DoFindFile")

This is an actual plugin I use in my Vim setup. You can grab the latest version from my Github repo.

Extra tip: add these too if you want to have a GUI menu for your new commands as well.

menu Project.Find\ File :call FG_RequestInputAction("FG_DoFindFile")
menu Project.Text\ Search :call FG_RequestInputAction("FG_DoSearchText")

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The best hack you should never use

Post by Nico Brailovsky @ 2016-11-22 | Permalink | 2 comments | Leave a comment

Please don't do this. But if you do: leave a comment here!

#define private public
#include "something"
#define private private

Found in some random project.

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Vim tip: custom commands

Post by Nico Brailovsky @ 2016-11-17 | Permalink | Leave a comment

If you have a function that you use a lot, you may find it interesting to use a custom command for it. Try this:

:command Foo echo('Hola!')

Now invoke the command with ':Foo' and Vim should say hello. Neat, huh? This is especially useful (and dangerous) when combined with cabbrev, like this:

:command! Foobar echo('Nope!')
:cabbrev close Foobar

If you try to :close a document, Vim will now say "Nope!". Other than using this to mess with someone's Vim session, you can replace builtin commands with your own tweaked functions. I tend to use that quite frequently in my own .vimrc.

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Ageing Stack overflow?

Post by Nico Brailovsky @ 2016-11-15 | Permalink | Leave a comment

Hacking away on a little side project of mine, I found myself checking Stack Overflow for implementation tips about things I don't usually work with. Android UI stuff, mostly, which apparently is a very dynamic and ever changing ecosystem. After more than a few wasted hours, I noticed a worrying trend: in SO, answers tend to age horribly. If you are looking for "How to do X in platform Y", you may find a 4 year old answer that solves the problem, but only for platform Y, version "ancient".

Information ageing is quite a problem on its own. The answer is still valid, and, for people working on that specific platform, probably relevant. This will make it the first answer, leaving a lot of people (like myself) frustrated because the solution won't work in newer platforms. Is there a solution? Implement some kind of ageing time-window for information? Make the date a more prominent search parameter? Explicitly specify your platform and environment's version when asking a question? I have no idea.

While Stack Overflow seems to exacerbate the issue, this is a problem even for products with a company actively maintaining their documentation. A very annoying example; looking for ways to manage the media key I ended up in a page which (as of August 2016) points to a very outdated API (registerMediaButtonEventReceiver, in case you are wondering). If even Google encounters problems when managing documentation ageing for their own products, what can we expect of people like us, who only have a tiny fraction of that budget?

/Rant