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28 lines
1.1 KiB
Text
28 lines
1.1 KiB
Text
The Problem
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===========
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Certain applications embedding Guile (Scwm, Guppi) have found it
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necessary to include hacked versions of scm_call_with_dynamic_root.
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They want to run user callbacks, but don't want the callback to be
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able to longjmp (via exceptions or continuations) randomly in and out,
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since the C code hasn't been written to dynamically wind/unwind local
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state. This is likely to be a common problem for users of Guile as an
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extension language.
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libguile/root.c:scm_call_with_dynamic_root seems to almost do this,
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but it has the apparently undesirable behaviour of unwinding the
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dynamic state when the protected procedure is called. In addition
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the implementation looks a bit heavy for use in every callback.
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scm_call_with_dynamic_root was implemented to support threading, so
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the needs of libguile itself should be considered. Other
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considerations are how any new interface interacts with error handling
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and reporting; whether a new interface is convenient to use from C;
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whether a new interface should also be available to Scheme code.
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Discussion
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==========
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Proposal
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========
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