Hi,
I stumbled upon what seems to me a strange issue in Pharo 5. The RBParser
fails to correctly parse the legacy FFI pragmas. This completely breaks down
the browser, the inspector and debugger (because as far as I understand all
use RBParser to correctly highlight syntax). I had the image crashed and
some red boxes at some point while insisting to inspect and debug. Overall
this is not a big issue but it raises some more general bells to me.
In order to reproduce this:
- load the official Pharo 5 (curl get.pharo.org/50+vm | bash)
- launch the image (./pharo-ui Pharo.image &)
- add the following repository
MCSmalltalkhubRepository
owner: 'panuw'
project: 'zeromq'
user: ''
password: ''
- load the last versions of ZeroMQ and ConfigurationOfZeroMQ (not sure if
the latter is needed)
- open a Nautilus Browser and look at the class method apiZmqBind:to: of the
ZmqApi class in the ZeroMQ package: you get a MessageNotUnderstood error
(receiver of keywords is nil). You can get past this by clicking on
"Abandon" but the source code is displayed in a corrupted way:
apiZmqBind: s
ocket to: endpoint <cdecl
- repeat a few times by looking at other methods until you get a red box:
then you cannot look at source code any more with this browser. If you are
obstinate and "lucky" you will succeed in crashing the image.
- you can pin the problem by running in a Playground
RBParser parseFaultyMethod: 'apiZmqBind: socket to: endpoint
<cdecl: long ''zmq_bind'' (ZmqApiSocket* char*) module:''zmq''>
^self externalCallFailed'.
and you'll see that the pragmas is not correctly parsed. (The root cause is
that the legacy adapter RBFFICallPragma does not follow the API defined by
its super class RBPragmaNode (selector, arguments, positions) and so is not
a properly defined node. I corrected the problem by computing and setting
the corresponding instance variables.)
1) As a beginner at Pharo, I find it difficult to deal with the various
versions of Pharo. ZeroMQ is the (only) Smalltalk-Pharo binding for zmq. It
dates back to Feb 2014 so I expected it to work in Pharo as of 3 years and a
half later (Pharo 6 dates back to June 2017).
I naively tried to load the package in a Pharo 6 image and it failed because
of a syntax error. As I had read a lot about the various FFI mechanisms, I
quickly understood that it must be because the FFI declarations in pragma
are not supported anymore.
I then loaded the package in a Pharo 5 image and I got the error that I
described. After finding the error and solving it, I guess that the FFI
declaration in pragma was barely supported in Pharo 5, which has already
switched to UFFI and that it is something dating back to Pharo 4. (I did not
try with Pharo 4 as I do not want to work with versions before 5).
Is there a way to know for a package what the compatible Pharo version is?
It seems that currently I have to look at dates, look at the features used
by the package and look for the history of development (fortunately the
mailing lists are easy to search) to understand which version is likely to
work.
Are not deprecations a bit too fast if a package written 3 years ago cannot
work in the latest Pharo version and trigger bugs in Pharo 5, which dates
back to May 2016 (so only a bit more than 2 years after)?
I find it a bit too fast as compared to mainstream languages. To my mind,
either deprecations should be slower or a version/dependencies system should
be there to help users.
2) Another question about versions: Pharo 6 is out since June, Pharo 7 is
under development. What is the status of Pharo 5? Already history or still
relevant?
I am asking because I corrected the problem of FFI declaration in pragma,
but it seems to me that it is not useful to publish this change as starting
from Pharo 6 this way to do FFI is not supported. So should I contribute? If
yes, how to "attach" the patch to Pharo 5?
3) As explained above, in Pharo 5, looking at the source trigger an error.
Even if this looks like a rare corner case, I think that the developer tools
should not trigger bugs when looking at source code, even less trigger a red
box in the source code viewer (in the browser, but the problem also occurs
--less strongly-- when looking at the object in an inspector: there should
not be "error printing" when it is only a syntax highlight problem). If the
code is malformed and the parser used to highlight syntax fails, there
should be a fallback such as the source code being displayed without any
highlight. It sends a very bad impression to have this kind of bugs when one
simply wants to look at code, not even running it.
I have not dug enough in this area of Pharo, but it seems to me that the
parser that is used to build the AST for code execution / method compilation
should not be the same as the parser used to highligh syntax. (Of course I
am not saying that there should be 2 distincts code base for the 2 parsers,
but they should at least run differently.) The first one must be strict with
errors as a malformed AST cannot be executed. The second one must be
lenient, as a malformed AST does not prevent to print the string of the
source code. Of course, at the end if the code is malformed there will be an
error at execution, but if the source code can be displayed even when it is
malformed, at least I have the opportunity to correct it so that it runs
correctly. (In this case, convert the old FFI pragma declaration into a
fficall:)
I may be missing something here but if this works the same in the most
up-to-date version of Pharo, the same kind of error might appear again.
What do you think?
4) A final remark: let us classify people as Beginner/Confirmed in
programming and B/C in Pharo (A BB is a beginner in programming and in
Pharo, a CC confirmed in both, a BC cannot exists and CB are those who
discover Pharo while knowing well other languages). Pharo seems to be great
for BB and CC. I went through the MOOC and the various books which are
great. My first steps in Pharo environment were great.
As a CC it seems to be great also as in the very small area of the system
where I took the time to drill into all the details, I could very easily
change things (and correct a bug), that would have been very difficult to
understand and change in a lot of other languages. Even hacking the VM seems
to be possible for a non-VM expert.
But I consider myself rather as a CB. As such I tend to try and do complex
things that I usually do in other languages and run into tricky problems.
These problems are rather dealt with and corrected by Pharo developers but
that as a user I would expect them to remain hidden to me or to be clearly
advertised in the docs. As compared to a BB, a CB is not going to stay in a
well delimited area where everything is smooth.
True, in a way it is a very strong incentive to become a Pharo expert! But I
am wondering if this aspect could be improved.
Thanks,
Bruno
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