Added explicit Enable/Disable for strip-on-save

This adds `EnableStripWhitespaceOnSave` and
`DisableStripWhitespaceOnSave` functions as an alternative for
`ToggleStripWhitespaceOnSave`.

Using these you can (correctly) set the variables for the buffer to
allow the toggle to work.  I updated the readme to reflect this change.

Closes #54

Author: docwhat

README.md

@@ -76,7 +76,7 @@ Whitespace highlighting is enabled by default, with a highlight color of red.
     *  If you want this behaviour by default for all filetypes, add the following to your `~/.vimrc`:
 
         ```
-        autocmd BufWritePre * StripWhitespace
+        autocmd BufEnter * EnableStripWhitespaceOnSave
         ```
 
         For exceptions of all see ```g:better_whitespace_filetypes_blacklist```.
@@ -85,7 +85,7 @@ Whitespace highlighting is enabled by default, with a highlight color of red.
         the following to your `~/.vimrc`:
 
         ```
-        autocmd FileType <desired_filetypes> autocmd BufWritePre <buffer> StripWhitespace
+        autocmd FileType <desired_filetypes> autocmd BufEnter <buffer> EnableStripWhitespaceOnSave
         ```
 
         where `<desired_filetypes>` is a comma separated list of the file types you want

plugin/better-whitespace.vim

@@ -156,16 +156,27 @@ function! s:StripWhitespace( line1, line2 )
     call cursor(l, c)
 endfunction
 
+" Strip whitespace on file save
+function! s:EnableStripWhitespaceOnSave()
+    let g:strip_whitespace_on_save = 1
+    call <SID>Echo("Strip Whitespace On Save: Enabled")
+    call <SID>SetupAutoCommands()
+endfunction
+
+" Don't strip whitespace on file save
+function! s:DisableStripWhitespaceOnSave()
+    let g:strip_whitespace_on_save = 0
+    call <SID>Echo("Strip Whitespace On Save: Disabled")
+    call <SID>SetupAutoCommands()
+endfunction
+
 " Strips whitespace on file save
 function! s:ToggleStripWhitespaceOnSave()
-    if g:strip_whitespace_on_save == 0
-        let g:strip_whitespace_on_save = 1
-        call <SID>Echo("Strip Whitespace On Save: Enabled")
+    if g:strip_whitespace_on_save == 1
+        call <SID>DisableStripWhitespaceOnSave()
     else
-        let g:strip_whitespace_on_save = 0
-        call <SID>Echo("Strip Whitespace On Save: Disabled")
+        call <SID>EnableStripWhitespaceOnSave()
     endif
-    call <SID>SetupAutoCommands()
 endfunction
 
 " Determines if whitespace highlighting should currently be skipped
@@ -175,6 +186,10 @@ endfunction
 
 " Run :StripWhitespace to remove end of line whitespace
 command! -range=% StripWhitespace call <SID>StripWhitespace( <line1>, <line2> )
+" Run :EnableStripWhitespaceOnSave to enable whitespace stripping on save
+command! EnableStripWhitespaceOnSave call <SID>EnableStripWhitespaceOnSave()
+" Run :DisableStripWhitespaceOnSave to disable whitespace stripping on save
+command! DisableStripWhitespaceOnSave call <SID>DisableStripWhitespaceOnSave()
 " Run :ToggleStripWhitespaceOnSave to enable/disable whitespace stripping on save
 command! ToggleStripWhitespaceOnSave call <SID>ToggleStripWhitespaceOnSave()
 " Run :EnableWhitespace to enable whitespace highlighting