patch 7.4.1373
Problem:    Calling a Vim function over a channel requires turning the
            arguments into a string.
Solution:   Add the "call" command. (Damien)  Also merge "expr" and "eval"
            into one.
diff --git a/src/testdir/test_channel.py b/src/testdir/test_channel.py
index 66fd48f..26c7dea 100644
--- a/src/testdir/test_channel.py
+++ b/src/testdir/test_channel.py
@@ -78,26 +78,26 @@
                         response = "ok"
                     elif decoded[1] == 'eval-works':
                         # Send an eval request.  We ignore the response.
-                        cmd = '["eval","\\"foo\\" . 123", -1]'
+                        cmd = '["expr","\\"foo\\" . 123", -1]'
                         print("sending: {}".format(cmd))
                         self.request.sendall(cmd.encode('utf-8'))
                         response = "ok"
                     elif decoded[1] == 'eval-fails':
                         # Send an eval request that will fail.
-                        cmd = '["eval","xxx", -2]'
+                        cmd = '["expr","xxx", -2]'
                         print("sending: {}".format(cmd))
                         self.request.sendall(cmd.encode('utf-8'))
                         response = "ok"
                     elif decoded[1] == 'eval-error':
                         # Send an eval request that works but the result can't
                         # be encoded.
-                        cmd = '["eval","function(\\"tr\\")", -3]'
+                        cmd = '["expr","function(\\"tr\\")", -3]'
                         print("sending: {}".format(cmd))
                         self.request.sendall(cmd.encode('utf-8'))
                         response = "ok"
                     elif decoded[1] == 'eval-bad':
                         # Send an eval request missing the third argument.
-                        cmd = '["eval","xxx"]'
+                        cmd = '["expr","xxx"]'
                         print("sending: {}".format(cmd))
                         self.request.sendall(cmd.encode('utf-8'))
                         response = "ok"
@@ -107,6 +107,11 @@
                         print("sending: {}".format(cmd))
                         self.request.sendall(cmd.encode('utf-8'))
                         response = "ok"
+                    elif decoded[1] == 'call-func':
+                        cmd = '["call","MyFunction",[1,2,3], 0]'
+                        print("sending: {}".format(cmd))
+                        self.request.sendall(cmd.encode('utf-8'))
+                        response = "ok"
                     elif decoded[1] == 'redraw':
                         cmd = '["redraw",""]'
                         print("sending: {}".format(cmd))
@@ -135,6 +140,9 @@
                         print("sending: {}".format(cmd))
                         self.request.sendall(cmd.encode('utf-8'))
                         response = ""
+                    elif decoded[1] == 'wait a bit':
+                        time.sleep(0.2)
+                        response = "waited"
                     elif decoded[1] == '!quit!':
                         # we're done
                         self.server.shutdown()
diff --git a/src/testdir/test_channel.vim b/src/testdir/test_channel.vim
index cfe3250..4d3b359 100644
--- a/src/testdir/test_channel.vim
+++ b/src/testdir/test_channel.vim
@@ -431,3 +431,26 @@
   " The server will wait half a second before creating the port.
   call s:run_server('s:open_delay', 'delay')
 endfunc
+
+"""""""""
+
+function MyFunction(a,b,c)
+  let s:call_ret = [a:a, a:b, a:c]
+endfunc
+
+function s:test_call(port)
+  let handle = ch_open('localhost:' . a:port, s:chopt)
+  if ch_status(handle) == "fail"
+    call assert_false(1, "Can't open channel")
+    return
+  endif
+
+  call assert_equal('ok', ch_sendexpr(handle, 'call-func'))
+  sleep 20m
+  call assert_equal([1, 2, 3], s:call_ret)
+endfunc
+
+func Test_call()
+  call ch_log('Test_call()')
+  call s:run_server('s:test_call')
+endfunc