Re: errno handling on sys.() and io.() functions

[Roberto Ierusalimschy <roberto@...>]

> Today I noticed that these functions also return errno as third return value.
> This seems to be mentioned in PIL, but is omitted in the reference manual. Is
> this officialy part of the Lua API, and is it safe to depend on this behaviour?

* http://www.lua.org/manual/5.2/manual.html#6.8

  Unless otherwise stated, all I/O functions return nil on failure (plus
  an error message as a second result and a system-dependent error code
  as a third result) [...]


* http://www.lua.org/manual/5.2/manual.html#pdf-os.remove

  os.remove (filename)
  [...] If this function fails, it returns nil, plus a string describing
  the error and the error code.

   ...

-- Roberto