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- Subject: Re: LUA_USE_APICHECK
- From: Lorenzo Donati <lorenzodonatibz@...>
- Date: Fri, 26 Aug 2011 13:57:58 +0200
On 26/08/2011 12.54, Axel Kittenberger wrote:
Sadly (for computer manuals writers, not for poets) natural languages
can be ambiguous, so Josh has a point in saying that valid(index) may be
a precondition, so the whole lot may also be pseudocoded as:
The manual doesn't say that non-acceptable indices should return NULL.
In my opinion it does.
"If the value at the given acceptable index is a full userdata,
returns its block address. If the value is a light userdata, returns
its pointer. Otherwise, returns NULL"
This english compiles into pseudo-code
if valid(index) and valueat(index) == userdata then return block address
elseif valid(index) and valueat(index) == light userdata then return pointer
else return NULL.
So an invalid index returns NULL.
if valid(index) then
if valueat(index) == userdata then return block end
elseif valueat(index) == lightuserdata then return pointer end
else return NULL end
From a natural language POV the interpretation may be correct as well,
especially if you interpret it in the context of the whole manual and
not in isolation (another "feature" of natural languages - they don't
have to stick only to locally declared information).
Of course the debate may well indicate that a more clear formulation
would be helpful, since it is a refman and not a poetry text (to keep
with the former analogy).