Re: Luerl
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- Subject: Re: Luerl
- From: David Manura <dm.lua@...>
- Date: 2012年2月22日 22:32:17 -0500
On Wed, Feb 22, 2012 at 11:56 AM, Jay Carlson <nop@nop.com> wrote:
> I see two interesting and broadly applicable patterns, and I'd
> probably use them both if I had them close at hand:
> Immutable tables: ft = final{k=2}
An alternative to preventing writes to tables (and not necessarily
better) is to check whether tables are changed after the fact. FWIW,
I posted a proof-of-concept library based on debug hooks that checks
that function parameters with names postfixed by '_c' are unchanged
across function calls [1]. Example:
-- example.lua
local function g(a,b)
b.x=1 -- ok
table.sort(a) -- bad
end
local function f(a_c, b)
return g(a_c, b) -- tail call test
end
f({'b','a'}, {})
$ lua52 -ldebugconstcheck example.lua
lua52: ./debugconstcheck.lua:46: const variable mutated
stack traceback:
[C]: in function 'error'
./debugconstcheck.lua:46: in function <./debugconstcheck.lua:17>
example.lua:8: in main chunk
[C]: in ?
[1] http://lua-users.org/wiki/ImmutableObjects