March 2019 - Pharo-users - lists.pharo.org

Re: [Pharo-users] Hmmm sending at:put: to an undefined object (nil) gives a confusing error message

by Richard O'Keefe

Byte arrays are not host specific. True. But integers are not byte arrays. They don't even contain byte arrays. Just like (boxed) Floats are not word arrays and don't contain word arrays. For what it's worth, I find that it's quite unusual for a method to change from private to public or vice versa. The basic problem with putting methods in a "private" category is that it has no actual effect. It was Smalltalk that taught me OO and the importance of encapsulation. But Smalltalk doesn't actually support encapsulation. Every detail of the implementation of Dictionary, for example, is exposed. And the practice of "self-encapsulation" is actually ANTI-encapsulation for this reason. Now there are several ways to implement hashed collections. The one I've had for years is pleasantly fast and pleasantly free of weird restrictions (keys/elements can be nil and why not). I've got a new one I'm working on that uses less space and is faster still. Because my dialect *enforces* encapsulation, when my testing is complete, I'll be able to swap the new version in, knowing that no external code can possibly depend on the implementation details.obj As a particular example, it was only when I implemented serialisation (nowhere up to Fuel's standards, of course) that I implemented #pvtInstVarAt:[put:] and an object is *still* completely and exclusively in charge of its own instance variables. I agree that using a prefix is not the best way to do this, but the eye soon learns to skip over it. It's not that much worse than "Inst" or "Var" or the pervasive and obtrusive use of prefixes on selectors in VisualAge Smalltalk. I think Pharo would be the better for having *some* way to enforce encapsulation, but what the best way is I don't claim to know. On Wed, 13 Mar 2019 at 21:35, K K Subbu <kksubbu.ml(a)gmail.com> wrote: > On 13/03/19 12:45 PM, Richard O'Keefe wrote: > > Base 256: that's an implementation detail. > > Little-endian: that's an implementation detail. > > Architecture-specific no. Implementation yes. But that should be fine > for private methods. > > > My Smalltalk uses base 65536 native-endian and > > takes some care not to let Smalltalk code find out. > > (Not least because on 64-bit machines I want to > > use base 2**32.) > > This would make it host-specific. Byte arrays are not host-specific. > > > For *private* methods, depending on otherwise > > hidden implementation details is fair enough. > > My Smalltalk picked up a convention from Squeak > > -- or rather, from the Squeak mailing list -- > > that a 'pvt' prefix on a selector makes it truly > > private and *enforces* that. Pharo does not seem > > pvt prefix is possibly inspired by Hungarian notation. I find that it > impairs readability and maintenance. Should a method change from private > to public or vice versa down the line, maintenance will be a nightmare. > My own preference is placing them in 'private' category (or even > private-* categories). > > > to have anything similar, and #at: is the epitome > > of a selector in extremely wide general use. > > Since #digitAt: exists -- and is what the integer > > classes use -- it is practically certain that #at: > > is sent to an integer only by mistake. > > You make a good point here. Perhaps #at:/#at:put: should throw an error > for all numbers and private methods could use basic versions instead. > > Regards .. Subbu > >

March 13, 2019

How to get to the bottom of the spinning beach ball when first entering Pharo

by Tim Mackinnon

Hi guys - this has come up before in the past - but Iâm really noticing it now having worked on a project for a few weeks. Every time I go into my image (by go into - I mean unsuspend my laptop and start using as its the current app, OR flipping to it from say reading email) I get a shining beach ball for 5-10 seconds and then the app is responsive and I can work on it. Itâs not all of the time, but Iâve noticed its not just my laptop warming up - as several times a day I see it when flipping back to it. How do I trouble shoot what is going on - does the system reporter tool tell me anything useful? I did notice my image has grown quite large - is it just that? Virtual Machine Statistics -------------------------- uptime 89h58m32s memory 409,608,192 bytes old 400,656,160 bytes (97.80000000000001%) young 3,931,080 bytes (1.0%) used 317,989,144 bytes (77.60000000000001%) free 86,598,096 bytes (21.1%) If it is memory - what would I look at to see why my memory usage is so large on a relatively small app with few dependencies (although I have been doing lots of iceberg commits and running tests, and using the debugger to explore etc) Tim

March 13, 2019

MSWindows Keymapping

by Craig Johnson

Hi All, I'm primarily a Windows user and I am finding the default key mapping very un-windows and it's preventing me from becoming immersed in the environment. Because I'm constantly having to reach for the mouse to switch windows etc. How easy would it be to change the key mapping to something that I'm more used to? Craig

March 13, 2019

Re: [Pharo-users] Hmmm sending at:put: to an undefined object (nil) gives a confusing error message

by K K Subbu

On 13/03/19 12:45 PM, Richard O'Keefe wrote: > Base 256: that's an implementation detail. > Little-endian: that's an implementation detail. Architecture-specific no. Implementation yes. But that should be fine for private methods. > My Smalltalk uses base 65536 native-endian and > takes some care not to let Smalltalk code find out. > (Not least because on 64-bit machines I want to > use base 2**32.) This would make it host-specific. Byte arrays are not host-specific. > For *private* methods, depending on otherwise > hidden implementation details is fair enough. > My Smalltalk picked up a convention from Squeak > -- or rather, from the Squeak mailing list -- > that a 'pvt' prefix on a selector makes it truly > private and *enforces* that.Â Pharo does not seem pvt prefix is possibly inspired by Hungarian notation. I find that it impairs readability and maintenance. Should a method change from private to public or vice versa down the line, maintenance will be a nightmare. My own preference is placing them in 'private' category (or even private-* categories). > to have anything similar, and #at: is the epitome > of a selector in extremely wide general use. > Since #digitAt: exists -- and is what the integer > classes use -- it is practically certain that #at: > is sent to an integer only by mistake. You make a good point here. Perhaps #at:/#at:put: should throw an error for all numbers and private methods could use basic versions instead. Regards .. Subbu

March 13, 2019

Re: [Pharo-users] Hmmm sending at:put: to an undefined object (nil) gives a confusing error message

by Richard O'Keefe

It's supposed to be on GitHub but I botched it. On Wed, 13 Mar 2019 at 21:08, Sven Van Caekenberghe <sven(a)stfx.eu> wrote: > > > > On 13 Mar 2019, at 08:15, Richard O'Keefe <raoknz(a)gmail.com> wrote: > > > > My Smalltalk > > Where can I have a look at that ? > >

March 13, 2019

Re: [Pharo-users] [ANN] CouchDB Client for Pharo

by Julien

Cool! I added an entry [1] for it to awesome-pharos [2]. Cheers, Julien Links: [1]: https://github.com/pharo-open-documentation/awesome-pharo/pull/56 [2]: https://github.com/pharo-open-documentation/awesome-pharo --- Julien Delplanque Doctorant Ã lâUniversitÃ© de Lille http://juliendelplanque.be/phd.html Equipe Rmod, Inria BÃ¢timent B 40, Avenue Halley 59650 Villeneuve d'Ascq NumÃ©ro de tÃ©lÃ©phone: +333 59 35 86 40 > Le 13 mars 2019 Ã 03:18, Esteban Maringolo <emaringolo(a)gmail.com> a Ã©crit : > > Hello all, > > I finished polishing the repository a CouchDB client for Pharo that I forked from an old, and seemingly abandoned, client for VisualWorks. > > I took that code and refactored heavily to use Pharo and Zinc core classes, and that included renaming the client classes, methods and the strategy used to map objects to/from JSON. > > It is available at: > https://github.com/eMaringolo/pharo-couchdb <https://github.com/eMaringolo/pharo-couchdb> > > I'm open to questions or suggestions about this or how to use it. > > Disclaimer: > This is mostly experimental since I'm not using it in production and was done as a means of exploration of CouchDB itself for a project I'm prospecting. > > There are a lot of features that could be added to the client, and things that could be refactored further (such as the class side request methods), but adding that is simple, and the current state provides almost feature complete coverage. > > Best regards, > > Esteban A. Maringolo

March 13, 2019

Re: [Pharo-users] Hmmm sending at:put: to an undefined object (nil) gives a confusing error message

by Sven Van Caekenberghe

> On 13 Mar 2019, at 08:15, Richard O'Keefe <raoknz(a)gmail.com> wrote: > > My Smalltalk Where can I have a look at that ?

March 13, 2019

Re: [Pharo-users] [ANN] CouchDB Client for Pharo

by Torsten Bergmann

March 13, 2019

Re: [Pharo-users] Hmmm sending at:put: to an undefined object (nil) gives a confusing error message

by Richard O'Keefe

Base 256: that's an implementation detail. Little-endian: that's an implementation detail. My Smalltalk uses base 65536 native-endian and takes some care not to let Smalltalk code find out. (Not least because on 64-bit machines I want to use base 2**32.) For *private* methods, depending on otherwise hidden implementation details is fair enough. My Smalltalk picked up a convention from Squeak -- or rather, from the Squeak mailing list -- that a 'pvt' prefix on a selector makes it truly private and *enforces* that. Pharo does not seem to have anything similar, and #at: is the epitome of a selector in extremely wide general use. Since #digitAt: exists -- and is what the integer classes use -- it is practically certain that #at: is sent to an integer only by mistake. On Wed, 13 Mar 2019 at 17:18, K K Subbu <kksubbu.ml(a)gmail.com> wrote: > On 12/03/19 9:25 AM, Richard O'Keefe wrote: > > Squeak where (20 factorial at: 1) answers 0 (oh dear oh dear oh > > dear). > > Richard, > > Could you please elaborate on why this is an error? > > Large integers are place value encoded (base 256 little endian) and > stored in byte arrays, so they need #at:/#at:put: (as private methods). > Place value encoding is not architecture-specific so it doesn't affect > portability of an image. > > Regards .. Subbu > >

March 13, 2019

Re: [Pharo-users] Hmmm sending at:put: to an undefined object (nil) gives a confusing error message

by Richard O'Keefe

Let's start with portability. I have ST/X, VAST, VW, Squeak, Pharo, GST, Dolphin, and some minor systems. GST and ST/X do not define #at: on any kind of integer at all. Why would they? #basicAt: will do the job, will it not? Dolphin defines #at:[put:] on Integer as self shouldNotImplement and so does VW. In VAST, 20 at: 1 => primitive failed 20 factorial at: 1 => 2192834560 In Squeak and Pharo, 20 at: 1 => not indexable 20 factorial at: 1 => 0 So sending #at: to an integer is not portable between mainstream Smalltalk systems, and for those Smalltalks that define it on large integers, the value is not consistent on the same machine and operating system. But it is worse than that. Maybe you do not care about any Smalltalk but Pharo, and there is a case to be made for that. But this is not consistent with *itself*. 1000000000000 at: 1 fails in a 64-bit VM, where that is a SmallInteger, but answers 0 in a 32-bit VM, where that is a LargePositiveInteger. But it gets *worse*. Numbers are not supposed to be mutable. But in a 32-bit VM, x := 1000000000000. x at: 1 put: 77. x => 1000000000077. I'm sorry, but I had enough grief with constants that weren't in Fortran 66. Again, there isn't the slightest need to define #at:put: on Large...Integers because #basicAt:put: exists. Indeed, we have #{basicAt:,at:,digitAt:}[put:] and surely with #digitAt:[put:] around we can let #at:[put:] be unimplemented on integers? There's a conceptual problem with #at: and #digitAt: as well. An integer can be viewed as a sequence of bits, right enough, but in a language without silly machine-word limits on integers, it's an *infinite* sequence. At least, if you define logical operations on bignums using a 2s-complement model, a LargePositiveInteger extends infinitely far with 0s and a LargeNegativeInteger extends infinitely far with 1s. GST gets this right. VW gets it right for large positive integers but wrong for large negative ones (or at least works on the absolute value without bothering to explain that). Ah heck, the whole thing is a mess. On Wed, 13 Mar 2019 at 17:18, K K Subbu <kksubbu.ml(a)gmail.com> wrote: > On 12/03/19 9:25 AM, Richard O'Keefe wrote: > > Squeak where (20 factorial at: 1) answers 0 (oh dear oh dear oh > > dear). > > Richard, > > Could you please elaborate on why this is an error? > > Large integers are place value encoded (base 256 little endian) and > stored in byte arrays, so they need #at:/#at:put: (as private methods). > Place value encoding is not architecture-specific so it doesn't affect > portability of an image. > > Regards .. Subbu > >

March 13, 2019