Load functions only when needed.

Even if this plugin is small, DNS zone editing may not be very frequent.
Therefore, there is no point defining those functions every time vim
start. Moving them to the autoload directory solve this problem.

autoload/dnsserial.vim

@@ -0,0 +1,39 @@
+" Copyright 2015 Rodolphe Breard
+"
+" Licensed under the Apache License, Version 2.0 (the "License");
+" you may not use this file except in compliance with the License.
+" You may obtain a copy of the License at
+"
+"   http://www.apache.org/licenses/LICENSE-2.0
+"
+" Unless required by applicable law or agreed to in writing, software
+" distributed under the License is distributed on an "AS IS" BASIS,
+" WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+" See the License for the specific language governing permissions and
+" limitations under the License.
+
+function! s:IncrementSerial(old_date, old_nb)
+    let curr_date = strftime("%Y%m%d")
+    if a:old_date ==? curr_date
+        let curr_nb = a:old_nb + 1
+        if curr_nb < 10
+            let curr_nb = "0".curr_nb
+        endif
+    else
+        let curr_nb = "01"
+    endif
+    return curr_date.curr_nb
+endfunction
+
+function! dnsserial#DNSSerialUpdate()
+    let pattern = '\(\d\{8}\)\(\d\+\)\s*;\s*\cserial'
+    if search(pattern) == 0
+        echom "No serial found."
+        return 0
+    endif
+    let old_pattern = matchlist(getline('.'), pattern)
+    let old_serial = old_pattern[1].old_pattern[2]
+    let new_serial = s:IncrementSerial(old_pattern[1], old_pattern[2])
+    execute "s/".old_serial."/".new_serial."/"
+    echom "Serial updated to ".new_serial."."
+endfunction

plugin/dnsserial.vim

@@ -12,30 +12,4 @@
 " See the License for the specific language governing permissions and
 " limitations under the License.
 
-function! s:IncrementSerial(old_date, old_nb)
-    let curr_date = strftime("%Y%m%d")
-    if a:old_date ==? curr_date
-        let curr_nb = a:old_nb + 1
-        if curr_nb < 10
-            let curr_nb = "0".curr_nb
-        endif
-    else
-        let curr_nb = "01"
-    endif
-    return curr_date.curr_nb
-endfunction
-
-function! s:DNSSerialUpdate()
-    let pattern = '\(\d\{8}\)\(\d\+\)\s*;\s*\cserial'
-    if search(pattern) == 0
-        echom "No serial found."
-        return 0
-    endif
-    let old_pattern = matchlist(getline('.'), pattern)
-    let old_serial = old_pattern[1].old_pattern[2]
-    let new_serial = s:IncrementSerial(old_pattern[1], old_pattern[2])
-    execute "s/".old_serial."/".new_serial."/"
-    echom "Serial updated to ".new_serial."."
-endfunction
-
-command! DNSSerialUpdate call s:DNSSerialUpdate()
+command! DNSSerialUpdate call dnsserial#DNSSerialUpdate()