2015-01-20 13:48 GMT+03:00 John Beckett <[email protected]>:
> Bao Niu wrote:
> > I am learning Vimscript and I wonder if there is any
> > difference between writing "function!" vs. "function"?
>
> Expanding on Tim's reply, suppose you have file h.vim which
> contains:
>
> function! Hello()
> echoerr 'Hello'
> endfunction
>
> In Vim, assuming the directory shown by :pwd is the directory
> holding h.vim, you can do the following to "source" the script:
>
> :so h.vim
>
> That executes h.vim which defines the function.
>
> You could edit h.vim and source it again, and the edited
> function would replace the original.
>
> The idea is to help you to not accidentally overwrite functions.
> If you do not have "!", the function will not be replaced if you
> try to define it again.
>
This idea is only useful for small scripts for one-time job. It is bad to
use it *always* because you cannot rely on the results of resourcing: there
are loads of “state” things that persist while they should not:
`:function!` overwrites existing function, but it is helpless if you
removed or renamed a function in a script and resource it to check whether
you have done everything right. It also will silently spoil user
configuration if user or some plugin he installed has chosen the same
function name.
Thus I suggest to *never* write :function! in any file in any directory in
&runtimepath, but this is OK for testing answers for stackoverflow or
vim-use, creating a script for a one-time job or something like this where
you know and control such leftovers or just do not care. If you really do
need to reload plugin without restarting Vim you can use same solution
frawor uses: almost all s: functions are put into s:F dictionary (actually,
in any dictionary: you just need to have them anonymous) so everything is
needed to delete s: functions is :unlet s:F. All functions that were not
put into s:F dictionary should be listed in s:_functions so frawor can
delete them for you when you unload plugin (so function definition looks
like
function Foo()
endfunction
let s:_functions += ['Foo']
). Then frawor receives reference to s: dictionary, so it is able to do
anything with it (including deleting s:F by unletting `F` key and iterating
over s:_functions). Since all functions are global you can also add s:Foo
function to a list (specifically frawor is also notified about plugin SID,
so it can replace s: with actual function prefix if needed).
But this reloading facility is rather complicated and if you are not basing
on frawor for some other reason it is easier and more robust to just reload
Vim and never use :function! or :command! in plugins.
>
> John
>
>
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