This paragraph only concerns those who want to emulate the file type plugins mechanism with version of VIM prior to the version 6.

In a few words, what I've understood of this new feature is that it enables to easily load (source) VIM files -- containing functions, mappings and other customizations -- and associate its definitions to a buffer regarding the filetype of what is edited within the buffer. Thus, it enables to define completely redundant mappings and associate them to different filetypes. For instance, the mapping of if could be expanded to if<cr>endif when editing VIM script files, to if () {<cr>} when editing C/C++/Java files, and not defined at all when editing HTML files.
There is no further need to define everything within the .vimrc file -- note also that writing all the autocommands within the .vimrc file obfuscates it and causes (me) headaches while it increases the complexity the maintenance of the whole stuff.

The filetypes plugins mechanism is thus very useful but it was not present in VIM until the version 6. Follows a way to emulate this feature with the previous versions of our favorite editor. What I propose seems to work since the version 5.6 and may be the previous ones -- don't remember.

The very first solution

The first smart thing to do is to split all the definitions regarding the filetype of the edited buffers ; it is a matter of clarity. Then quickly, several files emerge. One for LaTeX editing, one for HTML editing, one for C editing, and so on.
As the .vim extension is already used by the syntax files, I gave another extension to these files in order not to mess things up when managing completely different files. Years ago, I chose .set that stands for setting files. It is not perfect but at least I can't mix them up.

The second not so smart thing not to do is to load these files from syntax files : when VIM is upgraded from ver 5.x to 5.x+1, the syntax files are overloaded and all the modifications are lost.
A far more better solution is to add corresponding autocommands to the .vimrc. But, it is not said that filetypes defined within filetype.vim and myfiletype.vim are consistent with the autocommands present within .vimrc.

The quick solution

I opted for a solution directly inspired from the one adopted with syntax files. I copied and adapted syntaxfile.vim into mysettingfile.vim.

At first, it defines a command SetAuQuick that will ease the writing of all the autocommands.

    command -nargs=1 SetAuQuick au Syntax <args> so $VIMRUNTIME/settings/<args>.set

Then, for each filetype we have a dedicated macros file, the only thing to do is to call the command for the specific filetype. For instance, for e-mails composition, the line is :

    SetAuQuick mail

No more need to know exactly the definition of the filetype pattern.

Calling it

Of course, this new file has to be called. I am not sure is it the better place, but I chose to source it just after the syntax activation command : syntax on from my .vimrc (actually it is vimrc_core.vim in my configuration). Unfortunately my trick is not activated when the syntax colorization is off. If you have any idea in order to enhance this, please let me know !

Buffer relative considerations

At this point, every thing is nice until different types of buffers are loaded within the same VIM session. It becomes very annoying when VIM complains about redundant or inconsistent mappings. I observed this behavior a lot of times mainly when I want to update my set of abbreviations and mistyping corrections from the same session than my LaTeX one, or when I generate HTML files corresponding to different kind of source files (with 2HTML).

In order to correct this, the mapping abbreviations and other stuffs must become buffer relative. I found the solution to this issue thanks to the wonderful scripts buffoption.vim from Michael Geddes.

Using my scripts, the command to use in order to issue buffer relative loading of pseuso-ftplugins is SetAu. After a caching operation, the command issue a call to ReadFileTypeMap(). If you look closely at my mysettingfile.vim, you will notice that I load my e-mails composing plugins with SetAuQuick ; I consider that it is very unlikely to mix e-mail with any other kind of files.

Regarding buffoption.vim, you will be able to found the latest version on sourceforge. I understood that it enable to use the new form of mapping (with the <buffer> tag) and thus load real ftplugins files with VIM v5.x ; I haven't tested it until now. Nevertheless, I proposed a little patch over an older version of the script. The patch focuses on several issues :

• it works fine under PC-WinNT/zsh and Sun-Solaris/tcsh,
• it accepts noremap, noreab and noremenu commands,
• it supports abbreviations within FileType__ExeLine(...),
• it accepts "more" complex names for VIM filetypes like php,
• it caches the construction of the intermediary file -- also present in the latest version of the script.

Drawbacks

Last note : there are some drawbacks either inherent to the technique used or because I miss things (I guess that I missed something regarding syntax on or off). The points are :

• The trick is not activated when syntax highlighting is off.
• It is not designed to work properly with mapping embedded within functions ; for instance, the triggering features from common_brackets.vim do not work properly when switching buffers. From my point of view, this incompatibility with Triggers.vim is a real issue.
• At this time, I can not use real ftplugins (containing <buffer> tags). In order to do so, I will have to merge the latest buffoptions.vim from Michael Geddes with my patch. But well ... I lack time and by then I think that I will have definitively moved to the version 6.

Summing up of the files involved

mysettingfile.vim <raw file> Warning: filemtime() [function.filemtime]: Stat failed for ../vim/ressources/dollar_VIM/mysettingfile.vim (errno=2 - No such file or directory) in /mnt/133/sdb/f/b/hermitte/vim/dateOfScript.php on line 3 1st  January  1970	file in charge of the loading of the right script file according to the filetype of the buffer to be edited
buffoptions2.vim <raw file> Warning: filemtime() [function.filemtime]: Stat failed for ../vim/ressources/dollar_VIM/vim57/macros/buffoptions2.vim (errno=2 - No such file or directory) in /mnt/133/sdb/f/b/hermitte/vim/dateOfScript.php on line 3 1st  January  1970 buffoptions_mac2.vim <raw file> Warning: filemtime() [function.filemtime]: Stat failed for ../vim/ressources/dollar_VIM/vim57/macros/buffoptions_mac2.vim (errno=2 - No such file or directory) in /mnt/133/sdb/f/b/hermitte/vim/dateOfScript.php on line 3 1st  January  1970	files that enable to operate buffer relative loading of scripts
vimrc_core.vim	the root file (.vimrc) in charge of loading mysettingfile.vim

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