From: "Asbjørn Reglund Thorsen" <asbjoert@...>
Date: 2005-01-28T18:22:28+09:00
Subject: Re: Extending Ruby

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Thank you all for the response. :-)

I think comp.lang.ruby is a great newsgroup with friendly and=20
highly competent people. I really enjoy reading the postings of my=20
interesst, and that`s a lot. I spend nearly an hour reading this newsgroup=
=20
each day, and have allready posted at least 3 mail to it myselfe.

I am missing a site for n00bs to program extending Ruby though, does there=
=20
exist any ? I have read README.EXT and I have bought the wonderful=20
Pickaxe2.

What about "extending" the Ruby exam site=20
(http://www.rubygarden.org/ruby?RubyExam) with an "extending Ruby" part ?

On Fri, 28 Jan 2005, Charles Mills wrote:

> Tim Sutherland wrote:
>> In article <d4cf71b0050127093664c9bf7b@mail.gmail.com>, Lyle Johnson
> wrote:
>>> On Fri, 28 Jan 2005 01:56:24 +0900, Asbj=F8rn Reglund Thorsen
>>> <asbjoert@ifi.uio.no> wrote:
>>>
> (...)
>> As an alternative to rb_ary_store(), you can access the buffer
> underlying
>> the Array directly:
>>
>>     $result =3D rb_ary_new2(size);
>>     for (int i =3D 0; i < size; ++i)
>>     =09RARRAY($result)->ptr[i] =3D rb_float_new((double) p(i+1)));
>>
>> The latter is faster since it doesn't have to check things like
>>  - 'Do we need to increase the buffer size'
>>  - 'Is the buffer shared with another Array'
>>  - 'Is the Array frozen'
>>  ...etc.
>
> There is a gotcha to this though.
> rb_ary_new2(size) returns an array with length=3D=3D0 and capacity=3D=3Ds=
ize.
> The example you give above never increases length.
> You could fix this with
> RARRAY($result)->len =3D size;
> However, this is also a gotcha.  If you put it before the loop then the
> array is filled with a bunch of garabage references which will crash
> Ruby if the GC is run when rb_float_new() is called.  If you put it
> after he loop then all those floats you create could be destroyed by
> the GC, causing Ruby to crash later.
> rb_ary_store() is the simplest and safest solution.  You could also do:
>
> $result =3D rb_ary_new2(size);
> for ( ; RARRAY($result)->len < size; RARRAY($result)->len++) {
> int i =3D RARRAY($result)->len;
> RARRAY($result)->ptr[i] =3D rb_float_new((double) p(i+1)));
> }
>
>
> -Charlie
>
>
>
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