Re: Apache Portable Runtime

["Alex Queiroz" <asandroq@...>]

Hallo,

On 3/13/07, Peter Odding <xolox@home.nl> wrote:
> Hi all! (again)
>
> I'm writing a binding to the Apache Portable Runtime[1] for Lua. This is
> my first real C module for Lua and I've run into some `idiom
> mismatches', so I want to know what other potential users prefer:
>
> *Bitfields*
> APR uses bitfield extensively. Some of this functionality is too low
> level for Lua, but other stuff I really want to make available. For
> example when calling stat[2] some properties (13 total) might be
> expensive to retrieve, so they must be explicitly requested with a
> bitfield of property flags. Up till now I've used a string where each
> character maps to a flag. This is concise but feels obfuscated. The
> other option is to let the user create a bitfield from Lua numbers,
> which are `constants' my library makes available. This is clear and
> readable, but very verbose, and the operators | and + are not really
> compatible, i.e. adding the same flag twice basically destroys the
> bitfield... Any other suggestions?

    Make your function accept a list of strings, each one describing
an option. Strings are interned and comparing for equality is fast.
Then, in your C code, convert each string to an integer and "or" them.
The conversion can be done using an upvalue table.

> *Microseconds*
> The `Time Routines' module[3] uses microseconds as it's basic unit of
> time. Lua uses the C runtime, which most of the time uses seconds (on
> Windows and Linux at least AFAIK). Should my binding convert between the
> two, or let users do [T / 1000000] when they want to use os.date or
> os.difftime? If my reasoning is correct, the division my library makes
> should not lose precision when Lua uses floating point numbers... Right?
> Which would you prefer?

    Use fractional seconds.

--
-alex
http://www.ventonegro.org/