[tarantool-patches] [PATCH 4/5] box/lua/console: Provide output_default function to setup default output

[Cyrill Gorcunov <gorcunov@gmail.com>]

A user might need to use lua output as default serializer so instead
of requiring him setting up the output every new session that named
default output mode may be used instead with help of command

 > require('console').set_default_output("lua")

Also we provide

 > require('console').get_default_output("lua")

to obtain current setting.

Part-of #3834
---
 src/box/lua/console.lua | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/src/box/lua/console.lua b/src/box/lua/console.lua
index 7120bc8e6..db57a6d80 100644
--- a/src/box/lua/console.lua
+++ b/src/box/lua/console.lua
@@ -14,6 +14,10 @@ local net_box = require('net.box')
 local YAML_TERM = '\n...\n'
 local PUSH_TAG_HANDLE = '!push!'
 
+--
+-- Default output handler set to YAML for backward
+-- compatibility reason.
+local ouput_default_handler = { ["fmt"] = "yaml", ["opts"] = nil }
 local output_handlers = { }
 
 output_handlers["yaml"] = function(status, opts, ...)
@@ -99,6 +103,22 @@ local function output_parse(value)
     return false, msg:format(value)
 end
 
+local function set_default_output(value)
+    if value == nil then
+        error("Nil output value passed")
+    end
+    local status, err, fmt, opts = output_parse(value)
+    if status ~= true then
+        error(err)
+    end
+    ouput_default_handler["fmt"] = fmt
+    ouput_default_handler["opts"] = opts
+end
+
+local function get_default_output(value)
+        return ouput_default_handler
+end
+
 local function output_save(fmt, opts)
     --
     -- Output format descriptors are saved per
@@ -111,14 +131,8 @@ end
 
 local function format(status, ...)
     local d = box.session.storage.console_output
-    --
-    -- If there was no assignment yet provide
-    -- a default value; for now it is YAML
-    -- for backward compatibility sake (don't
-    -- forget about test results which are in
-    -- YAML format).
     if d == nil then
-        d = { ["fmt"] = "yaml", ["opts"] = nil }
+        d = ouput_default_handler
     end
     return output_handlers[d["fmt"]](status, d["opts"], ...)
 end
@@ -674,6 +688,8 @@ package.loaded['console'] = {
     start = start;
     eval = eval;
     delimiter = delimiter;
+    set_default_output = set_default_output;
+    get_default_output = get_default_output;
     ac = ac;
     connect = connect;
     listen = listen;
-- 
2.20.1