Why does this uncommon VIM dot concatenation syntax work, while my common VIM syntax doesn't?

Question

Customizing my .vimrc I added template (skeleton) file support. This auto-command rule from a book didn't do anything (no errors nor templates):

:autocmd BufNewFile * silent! Or $HOME/.vim/templates/%:e.tpl

This non-%e-wildcard version produced an error:

:autocmd BufNewFile *.html Or $HOME/.vim/templates/html.tpl

"test.html" [New File]
Error detected while processing BufNewFile Auto commands for "*.html":
E492: Not an editor command: Or $HOME/.vim/templates/html.tpl

In another post user orftz (+1) showed us an uncommon syntax (what I'd recognize as PHP) using concatenation and double quotes.

:autocmd BufNewFile * :silent! :exec ":0r " . $HOME . "/.vim/templates/" . &ft . ".tpl"

What's wrong with my version of the common and why does the other version work (I don't see any quoting in other vim scripts like this).

Answer 1

Quoting or concatenation has nothing to do with this.

The original command most likely doesn't do anything because you forgot to declare the Or command. I obviously don't know what the book you referring to uses, but it most likely looks like :command -nargs=1 Or read for example.

Your second command fails because you also removed silent! . This statement will suppress all errors. Since you removed it, Vim will now warn you that Or <argument> is not known by the editor, so the missing %:e has nothing to with it.

If you want to know more about %:e , read http://vimdoc.sourceforge.net/htmldoc/cmdline.html#%:e - it will be substituted by the extension of the current file.

---

EDIT: I see you were also confused by the . operator which can be used for string concatenation, and rightly so.

. simply means "concatenate the first string with the second", eg let val2 = 'value ' . val1 let val2 = 'value ' . val1 .

The hairy thing is that Vim has a few commands which do concatenation themselves, :execute , :echo and :echomsg to just name a few. Such commands will automatically add in a space character if you pass it several expressions. The following commands should all be equivalent:

:exec ":0r" $HOME . "/.vim/templates/" . &ft . ".tpl" :exec ":0r " . $HOME . "/.vim/templates/" . &ft . ".tpl" :exec (":0r " . $HOME . "/.vim/templates/" . &ft . ".tpl") :exec ":0r" ($HOME . "/.vim/templates/" . &ft . ".tpl")

This just goes to say that Vim script is all but pretty.