Re: [Tarantool-patches] [PATCH v2] error: Add __concat method to error object

[Sergey Ostanevich <sergos@tarantool.org>]

Hi!

Thanks for the patch!
LGTM.

Sergos


On 11 Nov 17:50, Oleg Babin wrote:
> From: Oleg Babin <babinoleg@mail.ru>
> 
> Usually functions return pair {nil, err} and expected that err is string.
> Let's make the behaviour of error object closer to string
> and define __concat metamethod.
> 
> Closes #4489
> ---
> 
> Changes in v2:
>   - Added tests
> 
> ---
>  src/lua/error.lua      |  8 +++++++
>  test/box/misc.result   | 47 +++++++++++++++++++++++++++++++++++++++++-
>  test/box/misc.test.lua | 17 ++++++++++++++-
>  3 files changed, 70 insertions(+), 2 deletions(-)
> 
> diff --git a/src/lua/error.lua b/src/lua/error.lua
> index 28fc0377d..b44fab7b6 100644
> --- a/src/lua/error.lua
> +++ b/src/lua/error.lua
> @@ -150,9 +150,17 @@ local function error_index(err, key)
>      return error_methods[key]
>  end
>  
> +local function error_concat(lhs, rhs)
> +    if lhs == nil or rhs == nil then
> +        error("attempt to concatenate struct error and nil")
> +    end
> +    return tostring(lhs) .. tostring(rhs)
> +end
> +
>  local error_mt = {
>      __index = error_index;
>      __tostring = error_message;
> +    __concat = error_concat;
>  };
>  
>  ffi.metatype('struct error', error_mt);
> diff --git a/test/box/misc.result b/test/box/misc.result
> index b2930515b..db184c037 100644
> --- a/test/box/misc.result
> +++ b/test/box/misc.result
> @@ -196,6 +196,51 @@ box.error.new()
>  ---
>  - error: 'Usage: box.error.new(code, args)'
>  ...
> +--
> +-- gh-4489: box.error has __concat metamethod
> +--
> +test_run:cmd("push filter '(.builtin/.*.lua):[0-9]+' to '\\1'")
> +---
> +- true
> +...
> +e = box.error.new(box.error.UNKNOWN)
> +---
> +...
> +'left side: ' .. e
> +---
> +- 'left side: Unknown error'
> +...
> +e .. ': right side'
> +---
> +- 'Unknown error: right side'
> +...
> +e .. nil
> +---
> +- error: 'builtin/error.lua: attempt to concatenate struct error and nil'
> +...
> +nil .. e
> +---
> +- error: 'builtin/error.lua: attempt to concatenate struct error and nil'
> +...
> +e .. box.NULL
> +---
> +- error: 'builtin/error.lua: attempt to concatenate struct error and nil'
> +...
> +box.NULL .. e
> +---
> +- error: 'builtin/error.lua: attempt to concatenate struct error and nil'
> +...
> +123 .. e
> +---
> +- 123Unknown error
> +...
> +e .. 123
> +---
> +- Unknown error123
> +...
> +e = nil
> +---
> +...
>  ----------------
>  -- # box.stat
>  ----------------
> @@ -1037,7 +1082,7 @@ error()
>  ---
>  - error: null
>  ...
> ---  A test case for bitwise operations 
> +--  A test case for bitwise operations
>  bit.lshift(1, 32)
>  ---
>  - 1
> diff --git a/test/box/misc.test.lua b/test/box/misc.test.lua
> index cc223b2ef..6104b935b 100644
> --- a/test/box/misc.test.lua
> +++ b/test/box/misc.test.lua
> @@ -59,6 +59,21 @@ e = box.error.new(box.error.CREATE_SPACE, "space", "error")
>  e
>  box.error.new()
>  
> +--
> +-- gh-4489: box.error has __concat metamethod
> +--
> +test_run:cmd("push filter '(.builtin/.*.lua):[0-9]+' to '\\1'")
> +e = box.error.new(box.error.UNKNOWN)
> +'left side: ' .. e
> +e .. ': right side'
> +e .. nil
> +nil .. e
> +e .. box.NULL
> +box.NULL .. e
> +123 .. e
> +e .. 123
> +e = nil
> +
>  ----------------
>  -- # box.stat
>  ----------------
> @@ -271,7 +286,7 @@ dostring('return abc')
>  dostring('return ...', 1, 2, 3)
>  --  A test case for Bug#1043804 lua error() -> server crash
>  error()
> ---  A test case for bitwise operations 
> +--  A test case for bitwise operations
>  bit.lshift(1, 32)
>  bit.band(1, 3)
>  bit.bor(1, 2)
> -- 
> 2.23.0
>