Re: Would an *AdaScript* language be a good / bad idea?

[Darren New <dnew@san.rr.com>]

Wes Groleau wrote:
> 
> > > And I don't see either example as being more difficult than
> > >   Invoke (Name_Of_File);
> >
> > Um.... But that doesn't do the same thing. What do you think the semantics
> 
> If Name_Of_File identifies the linked program, it does the same thing.

Uh, no. Your "invoke" replaces the currently executing program with a new
one. Tcl's "source" doesn't. 

> > Well, my point is all these things modify the currently-running program, so
> > yeah, it is a lot harder. If you haven't done a lot of work with this type
> > of scripting language, then I suspect you aren't really following what I'm
> > saying here.
> 
> After 10-15 years of Ada and other languages, including the usual
> incidental scripting, and having (unfortunately) for the last
> three having ksh, perl, and TCL be 75% of my job, I suspect I'm not
> is ignorant as you think.

I didn't say you were. I said "if". Now I'm trying to figure out why, if
you've used Tcl as extensively as you claim, you don't understand the
difference between Tcl's [source] command and Tcl's [exec] command.

> > The rest snipped, because I'm not sure you're making any sense.
> Maybe you need to read a little more carefully.

Then maybe you can explain why exec() is at all like [source].  

You're saying "it's simple to compile an Ada program and invoke it from
inside another Ada program", which I'm not arguing. I'm not discussing that
at all. I'm discussing adding code to the currently running process.
 
> > There's a tremendous difference between linking to DLLs, generating code on
> > the fly, and the "exec" system call.
> 
> It's certainly true that the extreme case I snipped
> is not appropriate for Ada.  That doesn't make the
> lesser cases in the previous posts difficult.

No, agreed. 

> Arguing with you is aiming at a rapidly moving target.

Actually, I think it's more like I make a statement, you interpret it thru
an Ada filter, and then say I'm wrong. When I clarify why what you're saying
isn't what I'm saying, you think I'm changing what I said.

For example, my comment that started this whole bit was 
> Another feature of scripting languages is the almost casual use of
> dynamically loaded code. It's not uncommon at all to calculate at run
> time what executable code will be loaded, for example. (Think "java
> applets" if you aren't familiar with programming other scripting
> languages.) I think this is fairly difficult to do in Ada.

Dynamically loaded code isn't "exec". I don't expect to restart my browser
every time I go to a different web page that has an applet on it. Where you
go from "dynamically loaded code" to "this is easy, just use exec" I'm not
sure.

 
> "There's a tremendous difference between" the
> 
>   source $Filename
> 
> that I challenged two posts back and the
> 
> > ... declares a new type at run-time
> > based on a user's input, perhaps a derived type of a tagged type, and loads
> > it into the currently running program, instantiates it, and sticks it into
> > an array of heterogenous objects all derived from that type, dynamically
> > dispatching to them. ...
> 
> of the last post. 

Errr, no. There's not. What do you think [package require] does?

> Although I could do that in Ada,
> too--but again, I would not recommend it.  Because
> when you go that far, you ARE getting quite difficult.
> And quite inefficient.

Except the exact same mechanism does both, in many scripting languages.

Nuff said. This is getting silly.

-- 
Darren New 
San Diego, CA, USA (PST). Cryptokeys on demand.
** http://home.san.rr.com/dnew/DNResume.html **
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     My brain needs a "back" button so I can
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