Re: Indexing a table with nil returns nil?
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- Subject: Re: Indexing a table with nil returns nil?
- From: Matthew Wild <mwild1@...>
- Date: Thu, 5 Apr 2012 17:38:03 +0100
On 5 April 2012 15:59, Enrico Colombini <erix@erix.it> wrote:
> On 05/04/2012 16.31, Dimitris Papavasiliou wrote:
>>
>> It doesn't bother me really and I imagine
>> it can be useful at times, [...]
>
>
> It can be useful, for example, to have 'nil propagation' in a chain of table
> accesses without having to check for key validity at each step.
In a "nested" chain like foo[bar[5]], yes. In an actual chain like
foo["bar"][5], no. Unless...
$ lua
Lua 5.1.4 Copyright (C) 1994-2008 Lua.org, PUC-Rio
> debug.setmetatable(nil, { __index = {} })
> a = {}
> =a.b.c.d
nil
Regards,
Matthew (diving for cover)