[Glass] [Pharo-users] [squeak-dev] Falsehoods programmers believe about Smalltalk

[Richard O'Keefe]

I have my own Smalltalk system implemented as a batch compiler via C.
This was originally just going to be a baseline for a student wanting
to work on JIT, but he went elsewhere and I found the system surprisingly
useful.  I also wanted something that hewed closely to the ANSI Smalltalk
standard, but could diverge in other matters (like not having dynamic code
modification).

- All Smalltalk bytecode sets are stack-based VM. (?)

My system has no bytecodes.  Smalltalk=>C=>native code.

- Bytecodes are always fixed-size. (?)

False back in the Blue Book.  Why does it matter anyway?

- Most of the time spent by a VM is in the instruction interpreter.
(actually it's in the GC right?)

There is no interpreter in my system, and many modern systems use a JIT.
That or they generate Javascript or JVM instructions or .NET or something,
and then _that_ gets turned into native code.

- You cannot serialize objects containing blocks. (IIRC one can use
MessageSends)

True in my system but that's because blocks contain pointers to native code
and may
contain pointers into the C stack.  I have plans to work around this, but
it has not been
a priority.  Something I don't ever plan to deal with is objects containing
references to
external objects (memory-mapped segments, file descriptors, sockets, ...)
and it is not
at all clear to me what the semantics should be.

BinaryObjectStorage in VisualWorks has no trouble with blocks.

I meant to try this in Pharo 7.0.  The image I just installed via the
launcher has
no DataStream, ReferenceStream, or SmartRefStream, but the class comment
for MCDataStream begins
"This is the save-to-disk facility.
 A DataStream can store one or more objects in a persistent form.

 To handle objects with sharing and cycles, you must use a ReferenceStream
 instead of a DataStream.  (Or SmartRefStream.)  ReferenceStream is
typically
 faster and produces smaller files because it doesn't repeatedly write the
same Symbols."

This was also the case back to  Pharo 2.0.  What *is* the persistence
scheme in Pharo these days?

- Image cannot be bootstrapped. (This is possible in ST/X and now in Pharo
I think).

There are no images in my system.

- All Smalltalks includes UI classes. (GemStone doesn't have AFAIK).

It depends on what you mean by "include".  Gnu Smalltalk *has* UI classes
but they
are not loaded by default.

- All implementations uses direct pointers, (GST?)

True in my case, but that's because I'm lazy and using the Boehm collector.

- All implementations uses green threads. (VAST? MT?)

False in my case.  A Process is a POSIX (red) thread and no green threads
exist.
This meant having to keep the interface fairly lean, but honestly wasn't
that hard,
since the Boehm collector handled the hard stuff.


On Tue, 22 Jan 2019 at 13:27, Hernán Morales Durand <
hernan.morales at gmail.com> wrote:

>
> Done.
>
> I have some possible myths, but I'd like to confirm or reject:
>
> - All Smalltalk bytecode sets are stack-based VM. (?)
> - Bytecodes are always fixed-size. (?)
> - Most of the time spent by a VM is in the instruction interpreter.
> (actually it's in the GC right?)
> - You cannot serialize objects containing blocks. (IIRC one can use
> MessageSends)
> - Image cannot be bootstrapped. (This is possible in ST/X and now in Pharo
> I think).
> - All Smalltalks includes UI classes. (GemStone doesn't have AFAIK).
> - All implementations uses direct pointers, (GST?)
> - All implementations uses green threads. (VAST? MT?)
>
> I'm sure people in this list will have a lot more myths heard from
> Conferences, Forums, Videos, Talks, etc. Like the guy who said Smalltalk
> was dead. So if you did something which could be ignored publicly, please
> don't hesitate to reply or ping me to get added as collaborator.
>
> Cheers,
>
> Hernán
>
>
>
> El dom., 20 ene. 2019 a las 22:41, Eliot Miranda (<eliot.miranda at gmail.com>)
> escribió:
>
>> Hi Hernán,
>>
>> On Sun, Jan 20, 2019 at 2:31 PM Hernán Morales Durand <
>> hernan.morales at gmail.com> wrote:
>>
>>> Hi there,
>>>
>>> I just created a GitHub repo to collect myths around Smalltalk-based
>>> technologies: Pharo, Squeak, VW, VAST, Smalltalk/X, GNU/ST, etc. in the
>>> spirit of the Falsehoods lists [1-4].
>>>
>>> This is just a draft now but please feel free to add falsehoods based on
>>> your own experiences. Examples are greatly appreciated.
>>>
>>
>> You want pull requests?  If not, would you give me write permission?  I'd
>> love to add to the "Smalltalk is obsolete" section...
>>
>>
>>>
>>> https://github.com/hernanmd/falsehoods_smalltalk
>>>
>>> Cheers,
>>>
>>> Hernán
>>>
>>> [1]
>>> https://infiniteundo.com/post/25326999628/falsehoods-programmers-believe-about-time
>>> [2]
>>> https://chiselapp.com/user/ttmrichter/repository/gng/doc/trunk/output/falsehoods.html
>>> [3]
>>> https://github.com/googlei18n/libphonenumber/blob/master/FALSEHOODS.md
>>> [4]
>>> https://meta-package-manager.readthedocs.io/en/develop/falsehoods.html
>>>
>>>
>>>
>>
>> --
>> _,,,^..^,,,_
>> best, Eliot
>>
>
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