From: William Djaja Tjokroaminata <billtj@...>
Date: 2002-10-24T23:43:17+09:00
Subject: Re: On Using Data_Wrap_Struct

Tim Hunter <Tim.Hunter@sas.com> wrote:
> As long as you need the array, (which I assume is as long as the Foo
> object is alive) you must mark its VALUE whenever gc calls Foo's mark
> function. Otherwise gc will delete it out from under you. The array,
> in turn, will take care of marking the VALUEs it contains, including
> the n and msg VALUEs you push on it.

> When you create a Foo object with Data_Wrap_Struct or
> Data_Make_Struct, include a pointer to a "mark function". GC will call
> the mark function periodically, during the "mark" part of its mark &
> sweep. It's the mark function's responsibility to mark any VALUEs
> contained in the Foo object so that gc can tell that they're still
> alive. Just add a call to rb_gc_mark(my_ary) in the mark function.

Mmmm... actually if the array is an instance variable, as Mark wrote

    ...Foo has an array member called @arr...

then we don't need to explicitly mark it, as Ruby already does it for us.

Regards,

Bill