[Vm-dev] questions about a couple of primitives

Florin Mateoc florin.mateoc at gmail.com
Mon Aug 31 20:51:30 UTC 2020

Hi Eliot,

Sorry about top-posting previously. Stupid Gmail!

Eliot Miranda via <https://support.google.com/mail/answer/1311182?hl=en>
4:40 PM (4 minutes ago)

to Open

On Mon, Aug 31, 2020 at 4:40 PM Eliot Miranda <eliot.miranda at gmail.com>

> Hi Florin,
> On Mon, Aug 31, 2020 at 1:35 PM Florin Mateoc <florin.mateoc at gmail.com>
> wrote:
>> Hi Eliot,
>> Thank you for your reply and for the extra details about #instVarAt:.
>> To answer your question, I would have expected the primitive to fail for
>> non-pointers objects, as I associate in my mind instvars with named
>> instvars, but I am not invested in this (mis)association, so thank you for
>> correcting it.
>> But regarding #ifCurtailed, I know that primitives198 1nd 199 are not
>> "real", I was referring to something else. The primitive failure code in
>> the method #ifCurtailed never touches the argument, regardless of the path
>> taken. I think that is incorrect, even if only for documentation purposes.
> I don't understand.  I see no error code.  We're talking about this method
> right?
> BlockClosure>>ifCurtailed: aBlock
> "Evaluate the receiver with an abnormal termination action.
> Evaluate aBlock only if execution is unwound during execution
> of the receiver.  If execution of the receiver finishes normally do
> not evaluate aBlock.  N.B.  This method is *not* implemented as a
> primitive.  Primitive 198 always fails.  The VM uses prim 198 in a
> context's method as the mark for an ensure:/ifCurtailed: activation."
> | complete result |
> <primitive: 198>
> result := self valueNoContextSwitch.
> complete := true.
> ^result

I did not mention an error code, I was talking about the "primitive failure
code", referring to the Smalltalk code that gets invoked when the primitive
fails (the three rows after the pragma).
This Smalltalk code does not touch the method's argument (aBlock), so it
looks as if aBlock is never evaluated

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.squeakfoundation.org/pipermail/vm-dev/attachments/20200831/769534bf/attachment-0001.html>

More information about the Vm-dev mailing list