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Make PyObject.typ a Rc<PyObject<PyClass>> #1811

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Merged
merged 3 commits into from
Apr 3, 2020
Merged

Make PyObject.typ a Rc<PyObject<PyClass>> #1811

merged 3 commits into from
Apr 3, 2020

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coolreader18
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@coolreader18 coolreader18 commented Mar 12, 2020 •
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The main motivator for this is to make the type hierarchy creation simpler and less error prone; this removes the trait object hack, including a few questionable transmutes.

@coolreader18 coolreader18 force-pushed the coolreader18/typ-generic-pyobj branch from 3f771cc to c16a257 Compare March 12, 2020 22:43
@coolreader18 coolreader18 marked this pull request as ready for review April 2, 2020 23:02
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Whoops, I forgot about this; I think it was actually fine when I first opened it.

@coolreader18 coolreader18 requested a review from youknowone April 2, 2020 23:02
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youknowone reviewed Apr 3, 2020
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Because I am not understanding this part very well, please check this is correct description of this patch:

We were using PyRef as shared pointer for PyObject::typ before, but now using Rust Rc instead of it.

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Fix typo
807c849 
Co-Authored-By: Jeong YunWon <youknowone@users.noreply.github.com>
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coolreader18 commented Apr 3, 2020 •
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Yeah; PyRef<T> is really just a wrapper around a PyObjectRef, which has a trait object inside of it and is therefore a "fat pointer" with a vtable pointer. In order to properly initialize a PyClassRef, then, we need to provide it with a vtable pointer to the correct vtable, which is pretty unsafe and requires some hacks to get the vpointer in the first place. With Rc<PyObject<PyClass>> (instead of Rc<PyObject<dyn PyObjectPayload>>), the inner type is just a plain struct, PyClass, and so it doesn't require any vtable pointers or anything like that.

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@coolreader18 coolreader18 merged commit a104d43 into master Apr 3, 2020
@coolreader18 coolreader18 deleted the coolreader18/typ-generic-pyobj branch April 3, 2020 17:20
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