From f692715444c6ddeb47bf87b53acf46798785290a Mon Sep 17 00:00:00 2001
From: cbdev <cb@cbcdn.com>
Date: Mon, 27 Apr 2020 20:54:02 +0200
Subject: Allow access to previous value in python handlers

---
 backends/lua.md    | 4 ++--
 backends/maweb.c   | 2 +-
 backends/python.c  | 9 +++++----
 backends/python.md | 3 +++
 4 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/backends/lua.md b/backends/lua.md
index 4e58ded..b2f40e0 100644
--- a/backends/lua.md
+++ b/backends/lua.md
@@ -26,8 +26,8 @@ The following functions are provided within the Lua interpreter for interaction
 | `thread(function)`		| `thread(run_show)`		| Run a function as a Lua thread (see below) |
 | `sleep(number)`		| `sleep(100)`			| Suspend current thread for time specified in milliseconds |
 
-While a channel handler executes, calling `input_value` for that channel returns the previous value. Once
-the handler returns, the internal buffer is updated.
+While a channel handler executes, calling `input_value` for that channel returns the previous value.
+The stored value is updated once the handler returns.
 
 Example script:
 ```lua
diff --git a/backends/maweb.c b/backends/maweb.c
index 5242f36..97d4cea 100644
--- a/backends/maweb.c
+++ b/backends/maweb.c
@@ -570,7 +570,7 @@ static int maweb_request_playbacks(instance* inst){
 				item_types,
 				view,
 				data->session);
-		rv |= maweb_send_frame(inst, ws_text, (uint8_t*) xmit_buffer, strlen(xmit_buffer));
+		maweb_send_frame(inst, ws_text, (uint8_t*) xmit_buffer, strlen(xmit_buffer));
 		DBGPF("Poll request: %s", xmit_buffer);
 		updates_inflight++;
 	}
diff --git a/backends/python.c b/backends/python.c
index 28b95a9..bd73a20 100644
--- a/backends/python.c
+++ b/backends/python.c
@@ -559,18 +559,19 @@ static int python_set(instance* inst, size_t num, channel** c, channel_value* v)
 	for(u = 0; u < num; u++){
 		chan = data->channel + c[u]->ident;
 
-		//update input value buffer
-		chan->in = v[u].normalised;
-
 		//call handler if present
 		if(chan->handler){
 			DBGPF("Calling handler for %s.%s", inst->name, chan->name);
 			data->current_channel = chan;
-			result = PyObject_CallFunction(chan->handler, "d", chan->in);
+			result = PyObject_CallFunction(chan->handler, "d", v[u].normalised);
 			Py_XDECREF(result);
 			data->current_channel = NULL;
 			DBGPF("Done with handler for %s.%s", inst->name, chan->name);
 		}
+
+		//update input value buffer after finishing the handler
+		chan->in = v[u].normalised;
+
 	}
 
 	//release interpreter
diff --git a/backends/python.md b/backends/python.md
index ab0fb38..a78d972 100644
--- a/backends/python.md
+++ b/backends/python.md
@@ -26,6 +26,9 @@ The `midimonster` module provides the following functions:
 | `manage(function, socket)`	| `midimonster.manage(handler, socket)`	| Register a (connected/listening) socket to the MIDIMonster core. Calls `function(socket)` when the socket is ready to read. Calling this method with `None` as the function argument unregisters the socket. A socket may only have one associated handler |
 | `cleanup_handler(function)`	| `midimonster.cleanup_handler(save_all)`| Register a function to be called when the instance is destroyed (on MIDIMonster shutdown). One cleanup handler can be registered per instance. Calling this function when the instance already has a cleanup handler registered replaces the handler, returning the old one. |
 
+When a channel handler executes, calling `midimonster.inputvalue()` for that exact channel returns the previous value,
+while the argument to the handler is the current value. The stored value is updated after the handler finishes executing.
+
 Example Python module:
 ```python
 import socket
-- 
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