feat(nested settings): better handling for setting nested settings

README.md

@@ -223,10 +223,16 @@ sh.repr = { newshell = { ... } }
 ```
 This would overwrite the entire `repr` table, erasing any already there.
 
-You may prefix the setting name with `_x_` to deep extend the tables together instead.
+There are 2 other methods designed for more easily setting nested values.
 ```lua
 local sh = require('sh')
-sh._x_repr = { newshell = { ... } }
+sh.proper_pipes = true
+-- setting a top level value like this will perform a key-based deep merge
+sh[{"repr"}] = { posix = { transforms = { function(v) print(v) return v end } } }
+-- or provide a list of names to directly set a nested value! (does not merge)
+sh[{"repr", "posix", "transforms"}] = { function(v) print(v) return v end }
+-- The above examples add a print to the posix repr without overwriting the other representation functions
+-- (so you can see what the final command looks like!)
 ```
 
 ## For nix users

lua/sh.lua

@@ -136,6 +136,21 @@ local function tbl_get(t, default, ...)
 	return t or default
 end
 
+---@param t table
+---@param value any
+local function setNested(t, value, ...)
+	local keys = {...}
+	local cur = t
+	for i = 1, #keys - 1 do
+		local k = keys[i]
+		if type(cur[k]) ~= "table" then
+			cur[k] = {}
+		end
+		cur = cur[k]
+	end
+	cur[keys[#keys]] = value
+end
+
 local warned_run_cmd_shim = false
 
 ---@param opts Shelua.Opts
@@ -419,6 +434,7 @@ local cmd_mt = {
 	end,
 }
 
+local has_warned_about_x_ = false
 local MT = {
 	---@type Shelua.Opts
 	__metatable = {
@@ -441,13 +457,27 @@ local MT = {
 	-- change settings by assigning them to table
 	__newindex = function(self, key, value)
 		if type(key) == "string" and key:sub(1, 3) == "_x_" then
-			local fkey = key:sub(4)
+			if not has_warned_about_x_ then
+				io.stderr:write("shelua: Using `sh._x_name = { nested = { settings = { to_be = \"merged\" } } }` to deep extend settings has been deprecated.\n")
+				io.stderr:write("Use `sh[{\"name\"}] = { nested = { settings = { to_be = \"merged\" } } }` instead.\n")
+			end
+			key = key:sub(4)
+			local opts = getmetatable(self)
+			if type(rawget(opts, key)) ~= "table" then
+				opts[key] = value
+			else
+				recUpdate(opts[key], value)
+			end
+		elseif type(key) == "table" and key[1] and #key == 1 then
+			key = key[1]
 			local opts = getmetatable(self)
-			if type(rawget(opts, fkey)) ~= "table" then
-				opts[fkey] = value
+			if type(rawget(opts, key)) ~= "table" then
+				opts[key] = value
 			else
-				recUpdate(opts[fkey], value)
+				recUpdate(opts[key], value)
 			end
+		elseif type(key) == "table" and #key > 1 then
+			setNested(getmetatable(self), value, (unpack or table.unpack)(key))
 		else
 			getmetatable(self)[key] = value
 		end

tests/test.lua

@@ -65,6 +65,42 @@ test('Check command with table args', function()
 	local r = sh.stat('/bin', { format = '%a %n' })
 	ok(tostring(r) == '755 /bin', 'stat --format "%a %n" /bin')
 end)
+test('Check settings deep merge via sh[{"key"}]', function()
+    local s = sh()
+    s[{"repr"}] = { posix = { foo = "bar" } }
+    local opts = getmetatable(s)
+    ok(opts.repr.posix.foo == "bar", "merge adds new nested key")
+    ok(opts.repr.posix.escape ~= nil, "merge preserves existing keys")
+end)
+
+test('Check settings nested set via multi-key table', function()
+    local s = sh()
+    s[{"repr", "posix", "foo"}] = "bar"
+    local opts = getmetatable(s)
+    ok(opts.repr.posix.foo == "bar", "nested set via multi-key table")
+end)
+
+test('Check table key merge preserves keys set via nested set', function()
+    local s = sh()
+    s[{"repr", "posix", "foo"}] = "bar"
+    s[{"repr"}] = { posix = { bar = "baz" } }
+    local opts = getmetatable(s)
+    ok(opts.repr.posix.foo == "bar", "merge preserves keys set via nested set")
+    ok(opts.repr.posix.bar == "baz", "merge adds new keys")
+end)
+
+test('Check sh[{"key"}] overwrites non-table settings', function()
+    local s = sh()
+    s[{"escape_args"}] = true
+    ok(getmetatable(s).escape_args == true, "sh[{key}] with non-table value overwrites")
+end)
+
+test('Check normal setting still works', function()
+    local s = sh()
+    s.escape_args = true
+    ok(getmetatable(s).escape_args == true, "direct setting works")
+end)
+
 test('Check concat command results', function()
 	local r = sh.echo 'Hello World' :sed("s/Hello/Goodbye/g") .. " " .. sh.echo 'Hello Lua' :sed "s/Hello/Goodbye/g"
 	ok(tostring(r) == 'Goodbye World Goodbye Lua', 'concat commands with string')