Re: [Tarantool-patches] [PATCH v17 1/2] box/cmod: implement cmod Lua module

[Cyrill Gorcunov via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

On Wed, Feb 10, 2021 at 03:24:47PM +0300, Cyrill Gorcunov wrote:
> 
> Once successfully loaded we can execute it. Note that unlike regular
> Lua functions the context of `C` functions is different. They never
> thrown an exception but return `true|nil, res` form where first value
> set to `nil` in case of error condition and `res` carries an error
> description.
> 
> Lets call the `cfunc_sum` with wrong number of arguments

Typo left in description. I force pushed an update (we always throw
an exception.
---
    First we should load it as
    
    ``` Lua
    m = require('cmod').load('cfunc')
    cfunc_sum = m:load('cfunc_sum')
    ```
    
    Once successfully loaded we can execute it. Lets call the
    `cfunc_sum` with wrong number of arguments
    
    ``` Lua
    cfunc_sum()
     | ---
     | - error: invalid argument count
    ```
    
    We will see the `"invalid argument count"` message in output.
    The error message has been set by the `box_error_set` in `C`
    code above.
    
    On success the sum of arguments will be printed out.
    
    ``` Lua
    cfunc_sum(1, 2)
     | ---
     | - 3
    ```