How to escape strings containing keys (when mapping) or call function with noremap

Question

Buffer-specific mappings are supported by vim out of the box. I am trying to implement window-specific mappings. My plan is to override the default keybinding by one that checks if a window-specific map should be executed, if so, it executes that, and if not, execues the default action for that keybinding (this is the ExecuteWindowMap function).

I'm having trouble with setting the map, see SetWindowMap. This function is called with an argument, a:map, a string of keys. It needs to include pass this string of keys to a function call, so it makes sense to use noremap; with map these keys would get pressed instead of passed to the function! On the other hand, I can only call that function using<CR>, which doesn't work with noremap!

I see two possible solutions:

1. Use map and somehow escape the key sequence contained in a:map.

2. Use noremap in a way that allows a calling a function.

   function! SetWindowMap(map)
     exe "noremap " . a:map . " :call ExecuteWindowMap('" . a:map . "')<CR>"
   endfunction
   
   function! ExecuteWindowMap(map)
     if exists("w:winMaps") && has_key(w:winMaps, a:map)
           exe w:winMaps[a:map]
     else
           exe "unmap " . a:map 
           exe "'a:map'"
           call SetWindowMap(a:map) 
     endif
   endfunction
   
   function! WindowMap(map, cmd)
     if !exists("w:winMaps")
           let w:winMaps = {}
     endif
     let w:winMaps[a:map] = a:cmd
     call SetWindowMap(a:map)
   endfunction
   

Answer 1

I was encouraged to answer my own question, I initially deleted it, because I was just not familiar with the way strings work in vim. When you use double quotes, characters preceded by a backslash are escaped before the string is used by the function. You thus need to use double backslashes, or use a literal string with single quotes. It is explained further here and here (Chapter 26 & 31 of Learn Vimscript the Hard Way).