#528: RFC
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Reporter: chromatic | Owner: chromatic
Type: roadmap | Status: new
Priority: normal | Milestone: 1.2
Component: none | Version:
Severity: medium | Keywords:
Lang: | Patch:
Platform: all |
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libparrot exports thousands of symbols. Many of those are the vtable
functions in our PMCs. They get exported because of the way initializing
a PMC builds its vtable. Look in src/pmc/class.c in a built Parrot source
tree for now. Parrot_Class_class_init() creates the Class PMC's vtable as
an array of function pointers. Because Class inherits some behavior from
the Default PMC, its vtable array contains pointers to functions declared
in Default.
That doesn't imply anything about the visibility of those symbols...
except that dynpmcs have the same strategy. Every dynpmc either
reimplements its own functions, or its initialization code has to refer to
symbols explicitly exported from libparrot to get at the function pointers
directly from the Default PMC, or whichever core PMC is its parent.
We need a way to map the appropriate slot in the vtable array for each
overridden entry. That's easy. We need a way for a dynpmc to access and
clone its parent's vtable. That's a little bit more work, if only because
we have to do this in generated code, and it's a divergence between how
dynpmcs initialize their vtables and how built-in PMCs initialize their
vtables.
Core PMCs all get stuffed into the same libparrot, so all of the necessary
symbols are visible.
I've already checked in code which initializes PMC vtables in the proper
order: parents before children. When we load a dynpmc group, all of
Parrot's vtables are assembled properly. The group initializes all of its
dynpmcs in the proper order.
When dynpmcs no longer access vtable functions directly, we can remove
PARROT_EXPORT from the generated vtable functions -- that's the goal of
this exercise.
--
Ticket URL: <https://trac.parrot.org/parrot/ticket/528>
Parrot <https://trac.parrot.org/parrot/>
Parrot Development
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