Re: Dynamic languages (again)

so, runtime MOP and runtime metaobjects do not belong to dynamic languages
only, static languages also can have runtime MOP.
i think maybe JAVA just has some runtime metaobjects. In java, does every
class exist as a metaobject?

2006/3/21, Jim Haungs <[email protected]>:
>
> There's nothing inherently reflective about dynamic languages, nor vice
> versa. The concepts are orthogonal.
>
> Dynamic (at least in my definition) means that variables are bound to
> values at run-time, and methods are dispatched via run-time look-up. True,
> this requires the VM to introspect the method dictionaries, but nothing
> requires the running user-level program to actively introspect anything.
>
> And Java has reflection without fully-dynamic typing. By "not
> fully-dynamic" I mean you can declare a variable to be of type Object, and
> put any reference type in there, but you can't put an unboxed primitive in
> there, something you can do in Smalltalk and Ruby because everything
> inherits from Object, even so-called "primitives."
>
> On 3/20/06, Cristina Videira Lopes <[email protected]> wrote:
> >
> >  Let me second the last sentence of the previous message. As a dynamic
> > reflective language, Ruby rocks! It's really cute. And it's quite amazing
> > what people are doing with it -- if you're into learning about it, don't
> > miss Ruby on Rails. I recently taught an undergrad course on PLs, where I
> > used Ruby at some point. The students were fascinated.
> >
> > (I have objections about some of the assumptions behind reflective
> > languages, in general, but that's another story...)
> >
> >
> >  ------------------------------
> > *From:* [email protected] [mailto:[email protected]] *On
> > Behalf Of *Jim Haungs
> > *Sent:* Monday, March 20, 2006 8:06 AM
> > *To:* Pascal Costanza
> > *Cc:* cao jing; [email protected]
> > *Subject:* Re: [aosd-discuss] discuss Digest, Vol 30, Issue 7
> >
> > In Smalltalk, dynamic typing and dynamic dispatch are closely related.
> > In Smalltalk, variables are merely slots for pointers; they can hold
> > anything. Everything is an Object, including booleans, integers and strings,
> > even blocks of code.
> >
> > When a message is sent to an object in a slot, the message name is
> > looked up dynamically, and if a matching method is found, it is executed.
> > This sounds egregiously slow, but good VM's play all sorts of tricks to
> > optimize the overhead away.
> >
> > It's also possible to handle the doesNotUnderstand: error raised by the
> > VM when an appropriate method is not found, yielding delicious possibilities
> > like faulting an object into memory from a database and then returning to
> > the original failed call with the correct object now reified.
> >
> > If you think Smalltalk is interesting but passe, check out Ruby. It's
> > basically Smalltalk reincarnated as a scripting language.
> >
> > On 3/20/06, Pascal Costanza <[email protected]> wrote:
> > >
> > >
> > > On 20 Mar 2006, at 02:10, cao jing wrote:
> > >
> > > > so, i think SMALLTALK is a kind of Dynamic language, right?
> > >
> > > Definitely yes.
> > >
> > > > or, maybe SMALLTALK has some features of static languages, if
> > > > it has, then what are they?
> > >
> > > Since Smalltalk allows you to change almost anything at runtime,
> > > including the class hierarchy, method definitions, etc., it's hard to
> > > state that anything about Smalltalk is static. However, I am no
> > > expert about Smalltalk, it may be that some things you can do have
> > > implications that I am not aware which would render them as
> > > practically static. It may be a better idea to ask these questions in
> > > a Smalltalk-related mailing list or newsgroup, like
> > > comp.lang.smalltalk.
> > >
> > > > BTW, is dynamic typing  the main feature  of  Dynamic language?
> > >
> > > It's certainly one of the main features. Dynamic dispatch is another
> > > one.
> > >
> > >
> > > Pascal
> > >
> > > --
> > > Pascal Costanza, mailto:[email protected], http://p-cos.net
> > > Vrije Universiteit Brussel, Programming Technology Lab
> > > Pleinlaan 2, B-1050 Brussel, Belgium
> > >
> > >
> > >
> > >
> > >
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> > > Check out the AOSD.net Wiki: http://aosd.net/wiki
> > >
> >
> >
>

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