Re: scm_local_eval is not available in Guile V2.

[Ian Hulin]

Hi David,
On 16/11/11 15:07, David Kastrup wrote:
> Ian Hulin <address@hidden> writes:
> 
>> Hi David,
>>
>>> <URL:http://code.google.com/p/lilypond/issues/detail?id=2043>
>>>
>>> Accompanying patch is relative to staging currently.  This should
>>> get you going again.  I don't particularly like this approach, and
>>> it is more complex and error-prone, and likely slower than the
>>> original version.  But without access to procedure-environments, I
>>> see no simpler way out here.
>>>
>> Thank you very much for getting on to this so quickly. I started
>> having a look at the Guile V1.8.7 code to see if we could "borrow" it
>> to put in our code base, but it looks like they've done some janitor
>> work with the code in addition to changing the name of the underlying
>> internal routine from scm-i-eval to eval.
>>
>> However, it may be work asking if the Guile team would be up to
>> supplying an unsupported (from their end) version which we could
>> stitch in to our code-base.
> 
> Well, getting a procedure-environment would appear to be incompatible
> with optimized compilation of the function containing #{ ... #}.  It
> would have to be executed in a mostly interpreted environment.  But
> since #{ ... #} itself calls the lexer and parser, this would be a
> non-issue except when the function does extensive loops before executing
> a single #{ ... #} statement.
> 
>> Andy and Ludo were quite helpful with providing us with a back-ported
>> module-export-all! when ly_make_module was in danger of breaking.
>>
>> Would it be worth asking on guile-user about a private copy of a
>> ported scm_local_eval?
> 
> I think it would likely be incompatible with the compilation model of
> Guile V2.  scm_local_eval alone does not do the trick: you also need
> something to feed it with, namely the result of calling
> procedure-environment.  I don't think you can get _that_ without having
> a whole interpreter built around it.  It is not a general Scheme feature
> but was specific to Guile, and I doubt it will come back.
> 
Rats.  I've just posted the question on guile-user.
Oh well, thanks for considering it anyway.

Cheers,
Ian