Vi: how to automatically insert spaces - keyboard-shortcuts

Question

I'm trying to write a nice feature for crazy people like me who like there lines to be perfectly aligned.
I often write some file in which the format is "key = value".
Since the key may contain an indeterminate number of character, one have to manually align the "=" symbols which is not cool.
Is there a way to tell vi "when someone type the equal character, then insert as spaces as necessary to go to the column 25, then write an the equal symbol"?
The second step will be to define a shortcut to apply this format to an entire file.
Any help would be appreciated.
Ben.

Answer 1

Map the behavior of = in Insert Mode.
Next code will add spaces until column 24 from current cursor position and will add an equal sign after it. If there were characters after cursor position (suppose in a middle of a word), those characters will be moved after column 25. Add it to your vimrc file and try.
"" If length of the line is more or equal to 24, add an equal sign at the end.
"" Otherwise insert spaces from current position of cursor until column 24
"" and an equal sign, moving characters after it.
function My_align()
let line_len = strlen( getline('.') )
if line_len >= 24
s/$/=/
return
endif
let col_pos = col('.')
exe 's/\%#\(.\|$\)/\=submatch(1) . printf( "%' . (24 - col_pos) . 's%s", " ", "=" )/'
endfunction
inoremap = <Esc>:call My_align()<CR>A
For second step, use the multiple repeats command, check for an equal sign and insert spaces until column 25 just before it. Won't work if equal sign is after column 25 before executing it, but you get the idea.
:g/=/exe 's/=/\=printf( "%' . ( 24 - stridx( getline('.'), "=" ) ) . 's", " " ) . submatch(0)/'