vim function for toggling colorschemes

At the moment I'm using two different keys to toogle the colorschem开发者_Python百科e

map <F8> :colors wombat256 <cr>
map <F9> :colors dimtag <cr>

I want to achieve a toggle behavior like this

function! ToggleDimTags()
if (g:colors_name == "wombat256")
  colors dimtag
else
  colors wombat256
endif
endfunction

My problem is that ToogleDimTags() is resetting the cursor position to the first line on every call, which is undesirable. Any suggestions appreciated.

---

As discussed in the comments, the problem is that your map calling :execute behaves a little differently, what you probably want is :call instead:

nnoremap <F5> :call ToggleDimTags()

To clarify what @ZyX was saying, :h :exec contains the following text:

                                                         :exe   :execute 
:exe[cute] {expr1} ..   Executes the string that results from the evaluation
                        of {expr1} as an Ex command.
                        [...]

So what :execute really does is evaluating the expression looking for a string that will be executed as an Ex command (also called colon commands). In other words:

exec ToggleDimTags() | " <-- ToggleDimTags() is evaluated and returns 0
exec 0

Which is:

:0

Now, :h :call:

                                                 :cal   :call   E107   E117 
:[range]cal[l] {name}([arguments])
                Call a function.  The name of the function and its arguments
                are as specified with |:function|.  Up to 20 arguments can be
                used.  **The returned value is discarded**.
                [...]

---

Update

I've been thinking about your function, and using the ternary operator and a bit of :execute magic, you can simplify it up to a point where you discard the extra function:

nnoremap <silent> <F9> :exec "color " .
    \ ((g:colors_name == "wombat256") ? "dimtag" : "wombat256")<CR>

Here, this nnoremap will not produce output (<silent>) and is based on :exec, which is followed by this expression:

"color " . ((g:colors_name == "wombat256") ? "dimtag" : "wombat256")

When g:colors_name is set to wombat256, the expression evaluates to:

"color dimtag"

Or, otherwise:

"color wombat256"

Then either one is evaluated by :exec. Of course you can join the lines (without forgetting to remove the backslash), I did it like this simply to avoid a too long line.