How guile knows?

How guile knows?

[Krzysztof Garus]

hello,

I can define a variable in one script (passed to gh_parse_string()), and
use in another. How guile knows I'll use it in future? Does it keep all
variables forever?

bajcik
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Re: How guile knows?

[Neil Jerram]

>>>>> "Krzysztof" == Krzysztof Garus <bajcik@kolos.math.uni.lodz.pl> writes:

    Krzysztof> hello, I can define a variable in one script (passed to
    Krzysztof> gh_parse_string()), and use in another. How guile knows
    Krzysztof> I'll use it in future? Does it keep all variables
    Krzysztof> forever?

(hoping I'm right this time ...)

Yes.  Variables belong to modules, and I don't believe there's any way
of unmaking a module.  (If you think your definitions are nothing to
do with modules, they're actually going into the module called
(guile-user).)

        Neil




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Re: How guile knows?

[Thomas Bushnell, BSG]

Neil Jerram <neil@ossau.uklinux.net> writes:

> Yes.  Variables belong to modules, and I don't believe there's any way
> of unmaking a module.  (If you think your definitions are nothing to
> do with modules, they're actually going into the module called
> (guile-user).)

There should be no way to unmake a module.

But certainly a module gets garbage collected when there are no more
references, right?



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Re: How guile knows?

[Lynn Winebarger]

On Thursday 09 January 2003 22:59, Thomas Bushnell, BSG wrote:
> Neil Jerram <neil@ossau.uklinux.net> writes:
> 
> > Yes.  Variables belong to modules, and I don't believe there's any way
> > of unmaking a module.  (If you think your definitions are nothing to
> > do with modules, they're actually going into the module called
> > (guile-user).)
> 
> There should be no way to unmake a module.
> 
> But certainly a module gets garbage collected when there are no more
> references, right?

   Since modules have absolute names that can be typed in any time, they
can't be garbage-collected any more correctly than global variable bindings
(i.e. you can't because "references" can exist external to the computer's memory,
in the future typing of the user).
   Unless I'm mistaken about the absolute naming, of course.

Lynn



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Re: How guile knows?

[Thomas Bushnell, BSG]

Lynn Winebarger <owinebar@free-expression.org> writes:

>  Since modules have absolute names that can be typed in any time,
> they can't be garbage-collected any more correctly than global
> variable bindings (i.e. you can't because "references" can exist
> external to the computer's memory, in the future typing of the
> user).  Unless I'm mistaken about the absolute naming, of course.

This is only partially true.  Global variables bindings most certainly
*can* be gc'd just like any other object.  However, the table in which
they are looked up (probably a module, but I'm prescinding from that)
is an object which holds references to them, and the live listener
holds a reference to the table, keeping them all alive.

Module names shouldn't be magic; the most obvious way to map module
names to modules is that the module names are variables in some scope.
Let's pretend that they are global variables (it doesn't matter
really).  That means that the binding from module-name to module is
like any other global variable: it can't be gc'd so long as there is a
reference to the global variable scope, such as, from a live listener.

But the *module* is not the module name.  The fact that the binding
from module-name to module is near infinite (though it's incorrect to
say it can't be gcd) has nothing to do with the module itself.

Thomas


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Re: How guile knows?

[Lynn Winebarger]

On Saturday 11 January 2003 20:25, Thomas Bushnell, BSG wrote:
> But the *module* is not the module name.  The fact that the binding
> from module-name to module is near infinite (though it's incorrect to
> say it can't be gcd) has nothing to do with the module itself.

       Are you sure that it's implemented that way in Guile, or just
propounding how it should be implemented? 

Lynn



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Re: How guile knows?

[Thomas Bushnell, BSG]

Lynn Winebarger <owinebar@free-expression.org> writes:

> On Saturday 11 January 2003 20:25, Thomas Bushnell, BSG wrote:
> > But the *module* is not the module name.  The fact that the binding
> > from module-name to module is near infinite (though it's incorrect to
> > say it can't be gcd) has nothing to do with the module itself.
> 
>        Are you sure that it's implemented that way in Guile, or just
> propounding how it should be implemented? 

The latter.


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Re: How guile knows?

[Thien-Thi Nguyen]

   From: tb@becket.net (Thomas Bushnell, BSG)
   Date: 11 Jan 2003 18:27:47 -0800

   The latter.

because in guile the binding of module-name to module is done by
procedure `resolve-module'.

thi


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Re: How guile knows?

[Paul Jarc]

Lynn Winebarger <owinebar@free-expression.org> wrote:
>    Since modules have absolute names that can be typed in any time, they
> can't be garbage-collected any more correctly than global variable bindings
> (i.e. you can't because "references" can exist external to the computer's memory,
> in the future typing of the user).
>    Unless I'm mistaken about the absolute naming, of course.

It's possible to create modules without adding them to the
conventional module namespace, using (make-module).  (And if you know
how the module namespace is implemented, you can remove an existing
module's binding from that namespace.)  So it is possible for a
module's reference count to drop to zero.  I would hope the module
would be gc'ed in that case.


paul


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Re: How guile knows?

[Marius Vollmer]

prj@po.cwru.edu (Paul Jarc) writes:

> I would hope the module would be gc'ed in that case.

That's what I expect as well.  Is there evidence that it isn't?

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Re: How guile knows?

[Paul Jarc]

Marius Vollmer <mvo@zagadka.ping.de> wrote:
> prj@po.cwru.edu (Paul Jarc) writes:
>> I would hope the module would be gc'ed in that case.
>
> That's what I expect as well.  Is there evidence that it isn't?

Not that I know of.  I have no reason to suspect a leak.


paul


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