Re: Bug in Lua when using signed long

[Mark Hamburg <mark@...>]

On Dec 13, 2009, at 11:14 AM, Mike Pall wrote:

> Mark Hamburg wrote:
>>> But it would make sense to use an out-of-the-box configuration
>>> where lua_Integer is a subset of lua_Number. One could just use
>>> LUAI_INT32.
>>> 
>>> Alas, it's a bit too late to fix that now. Changing lua_Integer
>>> would break the Lua 5.1 ABI.
>> 
>> My primary use case for integers exceeding the range of ints are
>> file offsets. These will pretty much always fit in the precision
>> afforded by double but often not in the precision afforded by
>> int.
> 
> But 64 bit file offsets are not specific to 64 bit platforms. In
> other words: using lua_Integer means your code would certainly
> break on a 32 bit platform.
> 
> That's why e.g. the LJ2 code for fp:seek() (in lib_io.c) uses the
> equivalent of lua_tonumber() and lua_pushnumber() for that purpose.

Good point. What I really want is: push really big integer (and its inverse) -- e.g., offset_t.

Mark