auto manage begin/end blocks in log file

gistfile1.vim

" Barry Arthur, June 2015
" Auto manage Begin/End blocks in log file
" Manual function to create new block

function! SpasmLogAuto()
  if ! exists('b:spasm')
    let b:spasm = 1
    $
    let now = strftime('%c')
    let last_entry = search('^\(Begin\)\|^\(End\)', 'bcpW')
    if last_entry == 0 || last_entry == 3
      call append('$', 'Begin ' . now)
    else
      call append('$', ['End','Begin ' . now])
    end
    $
  endif
endfunction

function! SpasmLogManual()
  silent! unlet b:spasm
  call SpasmLogAuto()
endfunction

augroup SpasmLog
  autocmd BufWinEnter *.log silent call SpasmLogAuto()
augroup END