[tarantool-patches] Re: [PATCH v2 7/8] sql: get rid of FuncDef function hash

[Kirill Shcherbatov <kshcherbatov@tarantool.org>]

>> I like this concept because it is uniform and all implementation-dependent
>> details (like the completion of the function definition initialization) are hidden
>> in the corresponding module (sql/func.c).
> 
> What does this code do? Why do you need an anonymous structure,
> instead of initializing struct func_sql_builtn object right away?
> What do you need the binary search for?
> Pre-ordering the array for the binary search is very fragile.

This new anonymous structure contain information both to complete
func_sql_builtn construction and func_def initialization.
...
        func->flags = sql_builtins[idx].flags;                                                             
	func->user_data = sql_builtins[idx].user_data;                                                     
	func->call = sql_builtins[idx].call;     
...
        def->is_deterministic = sql_builtins[idx].is_deterministic;                                        
	def->returns = sql_builtins[idx].returns;                                                          
	def->aggregate = sql_builtins[idx].aggregate;                                                      
	def->exports.sql = true;       
...

(def is an func_sql_builtin_new constructor argument)

The binary search is required to find corresponding metadata entry in
func_sql_builtin_new constructor. 

> Can this be coded in Lua, in upgrade.lua?
I mean in current implementation you need to add a snapshoot entry to
introduce a new function AND define a metadata entry in block with
binary search.