Re: Question about io.open modes

[Roberto Ierusalimschy <roberto@...>]

> I wonder why the 5.2 manual doesn't say it's the same as fopen,
> though. Did they change/add some modes, or did they just not want to
> have to guarantee fopen's behaviour? Or is it a simple omission?

Lua 5.2 did not changed/add modes, but it may restrict some. ANSI C
demands that 'mode' have a valid, specific format, and some machines
may have real problems with invalid modes. So we added a verification
step in io.open. Now, even if your native C fopen accepts extensions
(e.g., Linux seems to accept 'wb+'), io.open does not accept them.

(Anyway, a reference to 'fopen' mentioning this caveat would be
useful.)

-- Roberto