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Date: Sat, 25 Feb 2012 15:02:42 +0100
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To: Dmitri Snytkine <dsnytkine@ultralogistics.com>
Cc: internals@lists.php.net
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Subject: Re: [PHP-DEV] Is this correct behaviour with SplMinHeap?
From: colder@php.net (Etienne Kneuss)

Hi,

On Sat, Feb 25, 2012 at 14:21, Dmitri Snytkine
<dsnytkine@ultralogistics.com> wrote:
> I am not sure if this is a bug or not, but something is strange with this=
:
> I run this little test script, this one is posted on php.net in comments
> section
>
>
> class MySimpleHeap extends SplMaxHeap
> {
> =C2=A0 =C2=A0public function =C2=A0compare( $value1, $value2 ) {
> =C2=A0 =C2=A0 =C2=A0 =C2=A0return ( $value1 - $value2 );
> =C2=A0 =C2=A0}
> }
>
> $obj =3D new MySimpleHeap();
> $obj->insert( 4 );
> $obj->insert( 8 );
> $obj->insert( 1 );
> $obj->insert( 0 );
>
> foreach( $obj as $number ) {
> =C2=A0 =C2=A0echo $number."\n";
> }
>
> The output is 8 4 1 0
> Good.
> Now I change the
> class MySimpleHeap extends SplMaxHeap
> to
> class MySimpleHeap extends SplMinHeap
>
> run it again (now I expet to get lowest value first) and get exact same
> results back.
>
> Is this a bug?

No, this is not a bug. SplMin/MaxHeap simply define their own compare
method, but you overwrite it anyway.

If you specify the compare method, I don't believe it is useful to
extends SplMin/MaxHeap if you overwrite the compare method completely,
you should extend SplHeap directly in such cases.

Best,

>
>
>
> Dmitri Snytkine
> Web Developer
> Ultra Logistics, Inc.
> Phone: (888) 220-4640 x 2097
> Fax: (888) 795-6642
> E-Mail: dsnytkine@ultralogistics.com
> Web: www.ultralogistics.com
>
> "A Top 100 Logistics I.T. Provider in 2011"
>
>
>
>
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>



--=20
Etienne Kneuss
http://www.colder.ch