Changing the case within Snipmate.vim snippets?

Question

Is it possible to change the case of variable values within Snipmate snippets?

For example:

snippet dc
  def create
    @${1} = $1.new
  end

Should output:

def create
  @product = Product.new
end

I tried to use backticks to call a custom function:

snippet dc
  def create
    @${1} = `ToUpperCase('$1')`.new
  end

And defined this function in Vim:

function! ToUpperCase(str)
    let result = substitute(a:str, '\(\w\)', '\u\1', '')
    return result
endfunction

This doesn't work as it seems that Snipmate expands its $n variables after it has executed the backticks.

Answer 1

I made a little hack to snipMate to allow the functionality I was looking for.

Put this code in autoload/snipMate.vim to the end of the s:RemoveSnippet() function (after the line #14):

let linecount = len(getline("1", "$"))
for linenum in range(1, linecount)
    let line = getline(linenum)
    let line = substitute(line, '\v\%uc\(([^)]+)\)', '\U\1\E', 'g')
    let line = substitute(line, '\v\%ucfirst\(([^)]+)\)', '\u\1', 'g')
    call setline(linenum, line)
endfor

Now you can define snippets like this:

snippet dc
  def create
    @${1:product} = %ucfirst($1).new
    %uc($1) = "This is Ruby %uc(constant) example."
  end

Output:

def create
  @product = Product.new
  PRODUCT = "This is Ruby CONSTANT example."
end

Notice that the replacement is not done in real time but after you "quit" the snippet.