[added] stringx.apply_template for "$template_var" containing strings

stringx.lua

@@ -272,4 +272,12 @@ end
 --alias
 stringx.dedent = stringx.deindent
 
+--apply a template to a string
+--supports $template style values, given as a table or function
+-- ie ("hello $name"):format({name = "tom"}) == "hello tom"
+function stringx.apply_template(s, sub)
+	local r = s:gsub("%$(%w+)", sub)
+	return r
+end
+
 return stringx