Re: to serialize/deserialize closures; and multithreading

[Lynn Winebarger <owinebar@indiana.edu>]

On the other hand, you could just rely on guile's printer/reader
syntax and use that on the environment to export it and the
global variables.  I don't know if it prints everything in a
uniquely readable way, but it should handle standard scheme
that way.
    And environments in guile (last time I looked at the
evaluator) really are just binding lists. With deBruijn indices.
I can't remember exactly.  Use the source.

Lynn

Lynn Winebarger wrote:
> It's an interesting question all right.  What's the purpose of the
> "migration"?
>    Technically speaking, a closure is just a pair of pointers to its 
> code and
> its environment.  You could create a new "foreign reference" type (tag) 
> that
> would cause these to be looked up on the original computer whenever you 
> needed
> them.  That would handle synchronization.  Of course, you could also 
> make copies
> of everything.  I think tags are constant over all architechtures (last 
> I looked)
> but there are run-time allocated types that you'd have to do some work for
> (I think - I don't remember what they're called).
>    Anyway, besides taking care of the tags/synchronizing run-time 
> allocated types/
> handling endianness issues, you'd need to munge pointers according to 
> whereever
> they would be newly allocated on the new machine.  It would probably be 
> easiest
> to just number copies of the cells from 0 to whatever for the transport 
> over and the
> allocator on the other end could relabel them to the actual values.
>    Also, you'd need to check that any symbols referenced by the code or 
> variables were
> actually in existence in the new guile instance's symbol table.  And 
> that global
> variables referenced by the code got copied (as well as the lexical 
> variables).
> So will be recursively nasty.
> 
> Good Luck.
> 
> Lynn
> 
> Greg Troxel wrote:
> 
>>   1. If I have a scheme value that is a closure, is there any way that 
>> I can
>>   serialize this closure (from C code) into a form that it can be
>>   deserialized back into a SCM closure variable (again, by C code)?  I 
>> can
>>   assume for this question that both ends of the serial line are 
>> running the
>>   same version of gnu guile and my software, but cannot assume that both
>>   ends are running on the same computer architecture.  Would it instead
>>   only be possible for me to transfer closures as their scheme source.
>>
>> I'm not even sure it is well-defined what it means to migrate a
>> closure.  Should a mutation on the new computer of a captured variable
>> affect the old computer?
>>
> 
> 
> 
> 
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> 
> 




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