From: "Jonas Roberto de Goes Filho (sysdebug)" <jonas@...>
Date: 2007-09-27T23:34:20+09:00
Subject: Re: Ruby's a = b vs PHP5's $obj1 =& $obj2

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SpringFlowers AutumnMoon wrote:
> Just want to confirm Ruby's
>=20
>   a =3D b
>=20
> is the same as PHP5's
>=20
>   $obj1 =3D $obj2
>=20
> in other words, the reference is copied.
>=20
> While
>=20
>   $obj1 =3D& $obj2
>=20
> or
>=20
>   $obj1 =3D &$obj2
>=20
> in both PHP4 and PHP5 isn't the same as Ruby's   a =3D b
>=20
> $obj1 and $obj2 just become synonyms...
>=20
> and after
>=20
> $obj1 =3D new Foo("foo1");
> $obj2 =3D& $obj1
> $obj2 =3D new Foo("bar1");
>=20
> $obj1 and $obj2 have the same content, as they are just synonyms. (not =
a
> clone, not same reference, but just synonyms).  The "foo1" object is
> garbage-collected since no one is referencing it.
>=20
> this is giving me an initial headache... until maybe after i get used t=
o
> it.

Hello,

In PHP, $obj1 =3D & $obj2 means that both $obj1 and $obj2 points to the=20
same content. Its like hardlinks in Unix.

In Ruby, depends of type of variable. If type of variable as object, its =

work like as PHP. If type of variable as a number, its not work as PHP.

See an example:

sysdebug(main):014:0> class A
sysdebug(main):015:1> def setName(name)
sysdebug(main):016:2> @name =3D name
sysdebug(main):017:2> end
sysdebug(main):018:1> def putsName
sysdebug(main):019:2> puts @name
sysdebug(main):020:2> end
sysdebug(main):021:1> end
=3D> nil
sysdebug(main):022:0>
sysdebug(main):023:0*
sysdebug(main):024:0* a =3D A.new
A
=3D> #<A:0xb7cce1f8>
sysdebug(main):025:0> b =3D a
=3D> #<A:0xb7cce1f8>
sysdebug(main):026:0> a.setName('Jonas')
=3D> "Jonas"
sysdebug(main):027:0> a.putsName
Jonas
=3D> nil
sysdebug(main):028:0> b.putsName
Jonas
=3D> nil
sysdebug(main):029:0> b.setName('Ana')
=3D> "Ana"
sysdebug(main):030:0> a.putsName
Ana
=3D> nil


But in number types:


sysdebug(main):031:0> num1 =3D 1
=3D> 1
sysdebug(main):032:0> num2 =3D num1
=3D> 1
sysdebug(main):033:0> num2
=3D> 1
sysdebug(main):034:0> num1 =3D 2
=3D> 2
sysdebug(main):035:0> num2
=3D> 1
sysdebug(main):036:0>


Regards,

--=20
Jonas Roberto de Goes Filho (sysdebug)
http://goes.eti.br


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