How to inspect userdata in lua

Question

I am using inspect.lua to inspect table to string.

But, if the value is a userdata, it returns just <userdata 1>

I really need to know what the userdata type is, what the userdata value is, it's very important for debuging, I don't want do it in any IDE, I just want something can help me debug by print staffs.

Answer 1

You cannot.

From the manual :

The type userdata is provided to allow arbitrary C data to be stored in Lua variables. A userdata value is a pointer to a block of raw memory. [...] Userdata has no predefined operations in Lua, except assignment and identity test.

As indicated by @Eric, the only thing you can do from Lua is inspect the metatable :

print(inspect(getmetatable(someuserdata)))

If you are using the C API, you should be able to register a custom function that prints whatever is held by the block.