Make compatibility with miscellaneous scripts explicit

Author: xolox

autoload/xolox/misc/README.md

@@ -1,24 +1,49 @@
 # Miscellaneous auto-load Vim scripts
 
-The git repository at <http://github.com/xolox/vim-misc> contains Vim scripts that are used by most of the [Vim plug-ins I've written] [plugins] yet don't really belong with any single one. I include this repository as a subdirectory of my plug-in repositories using the following commands:
+The git repository at [github.com/xolox/vim-misc] [repository] contains Vim scripts that are used by most of the [Vim plug-ins I've written] [plugins] yet don't really belong with any single one. I include this repository as a subdirectory of my plug-in repositories using the following commands:
 
     $ git remote add -f vim-misc https://github.com/xolox/vim-misc.git
     $ git merge -s ours --no-commit vim-misc/master
     $ git read-tree --prefix=autoload/xolox/misc/ -u vim-misc/master
     $ git commit -m "Merge vim-misc repository as subdirectory"
 
-To update a plug-in repository to the latest versions of the miscellaneous auto-load scripts I execute the following command:
+The above trick is called the [subtree merge strategy] [merge-strategy]. To update a plug-in repository to the latest version of the miscellaneous auto-load scripts I execute the following command:
 
     $ git pull -s subtree vim-misc master
 
+## Why make things so complex?
+
+I came up with this solution after multiple years of back and forth between Vim Online users, the GitHub crowd and my own sanity:
+
+1. When I started publishing my first Vim plug-ins I would prepare ZIP archives for Vim Online using makefiles. The makefiles would make sure the miscellaneous scripts were included in the uploaded distributions. This had two disadvantages: It lost git history and the repositories on GitHub were not usable out of the box, so [I got complaints from GitHub (Pathogen) users] [github-complaints].
+
+2. My second attempt to solve the problem used git submodules which seemed like the ideal solution until I actually started doing it. Submodules are not initialized during a normal `git clone`, you need to use `git clone --recursive` instead but Vim plug-in managers like [Pathogen] [pathogen] and [Vundle] [vundle] don't do this (at least [they didn't when I tried] [vundle-discussion]) so people would end up with broken checkouts.
+
+3. After finding out that git submodules were not going to solve my problems I searched for other inclusion strategies supported by git. After a while I came upon the [subtree merge strategy] [merge-strategy] which I have been using for more than two years now.
+
+## Compatibility issues
+
+Regardless of the inclusion strategies discussed above, my current scheme has a flaw: If more than one of my plug-ins are installed in a Vim profile using [Pathogen] [pathogen] or [Vundle] [vundle], the miscellaneous autoload scripts will all be loaded from the subdirectory of one single plug-in.
+
+This means that when I break compatibility in the miscellaneous scripts, I have to make sure to merge the changes into all of my plug-ins. Even then, if a user has more than one of my plug-ins installed but updates only one of them, the other plug-ins (that are not yet up to date) can break (because of the backwards incompatible change).
+
+The `xolox#misc#compat#check()` function makes sure that incompatibilities are detected early so that the user knows which plug-in to update if incompatibilities arise.
+
 ## Contact
 
 If you have questions, bug reports, suggestions, etc. the author can be contacted at <peter@peterodding.com>. The latest version is available at <http://peterodding.com/code/vim/misc> and <http://github.com/xolox/vim-misc>.
 
 ## License
 
-This software is licensed under the [MIT license](http://en.wikipedia.org/wiki/MIT_License).  
+This software is licensed under the [MIT license] [mit].  
 © 2013 Peter Odding &lt;<peter@peterodding.com>&gt;.
 
 
+[github-complaints]: https://github.com/xolox/vim-easytags/issues/1
+[merge-strategy]: http://www.kernel.org/pub/software/scm/git/docs/howto/using-merge-subtree.html
+[mit]: http://en.wikipedia.org/wiki/MIT_License
+[pathogen]: http://www.vim.org/scripts/script.php?script_id=2332
 [plugins]: http://peterodding.com/code/vim/
+[repository]: https://github.com/xolox/vim-misc
+[vundle-discussion]: https://github.com/gmarik/vundle/pull/41
+[vundle]: https://github.com/gmarik/vundle

autoload/xolox/misc/compat.vim

@@ -0,0 +1,23 @@
+" Vim auto-load script
+" Author: Peter Odding <peter@peterodding.com>
+" Last Change: April 20, 2013
+" URL: http://peterodding.com/code/vim/misc/
+
+" The following integer will be bumped whenever a change in the miscellaneous
+" scripts breaks backwards compatibility. This enables my Vim plug-ins to fail
+" early when they detect an incompatible version, instead of breaking at the
+" worst possible moments :-).
+let g:xolox#misc#compat#version = 1
+
+" Remember the directory where the miscellaneous scripts are loaded from
+" so the user knows which plug-in to update if incompatibilities arise.
+let s:misc_directory = fnamemodify(expand('<sfile>'), ':p:h')
+
+function! xolox#misc#compat#check(plugin_name, required_version)
+  if a:required_version != g:xolox#misc#compat#version
+    let msg = "The %s plug-in requires version %i of the miscellaneous scripts, however version %i was loaded from %s!"
+    throw printf(msg, a:plugin_name, a:required_version, g:xolox#misc#compat#version, s:misc_directory)
+  endif
+endfunction
+
+" vim: ts=2 sw=2 et

autoload/xolox/notes.vim

@@ -1,14 +1,16 @@
 " Vim auto-load script
 " Author: Peter Odding <peter@peterodding.com>
-" Last Change: April 18, 2013
+" Last Change: April 21, 2013
 " URL: http://peterodding.com/code/vim/notes/
 
 " Note: This file is encoded in UTF-8 including a byte order mark so
 " that Vim loads the script using the right encoding transparently.
 
-let g:xolox#notes#version = '0.17.1'
+let g:xolox#notes#version = '0.17.2'
 let s:scriptdir = expand('<sfile>:p:h')
 
+call xolox#misc#compat#check('notes', 1)
+
 function! xolox#notes#init() " {{{1
   " Initialize the configuration of the notes plug-in. This is a bit tricky:
   " We want to be compatible with Pathogen which installs plug-ins as