February 2015 - Pharo-dev - lists.pharo.org

Re: [Pharo-dev] [Slots] Invisible Slots

by Marcus Denker

> > Next: When building classes with Slots, the class builder need to call back on the slot and hand the class to each. Then the slot > can reflectively change the class, e.g. the PropertySlot will check if there is already a hidden property base slot and if not, add it > reflectively). This is now done: https://pharo.fogbugz.com/f/cases/14876/Add-call-back-in-ClassBuilder-to-ca… Marcus

Feb. 6, 2015

Re: [Pharo-dev] Parsing float difference between 2.0 and 3.0, was it on purpose?

by Yuriy Tymchuk

We have merged the parsers into one, because we had 3 parsers that didnât have any dedicated use-cases, juts were developed historical as at some point someone needed a bit more functionality, and then different parsers were used randomly on the system. As for the expression - yes we have to decide about it. If itâs only about being able to use exponent in float literals, one can use: âNumber readFrom: '2.5850009999999998e04ââ. If itâs about being similar to the other languages, we can also decide does it make sense to have a +2 literal. Uko > On 06 Feb 2015, at 09:04, Marcus Denker <marcus.denker(a)inria.fr> wrote: > > >> On 06 Feb 2015, at 09:02, stepharo <stepharo(a)free.fr> wrote: >> >> >> Le 5/2/15 10:40, Sven Van Caekenberghe a Ã©crit : >>>> On 05 Feb 2015, at 10:36, Ben Coman <btc(a)openInWorld.com> wrote: >>>> >>>> I personally would prefer to be able to use exponents. No sure what the big picture is. >>>> cheers -ben >>> Of course exponents are still supported ;-) >>> >>> The discussion is about the + sign for positive exponents. I am not sure, but I think that traditional Smalltalk did not support this, but it was added to support common practice in other languages. Now it is apparently gone again, probably not on purpose. >> >> I do not know I think that marcus removed it to avoid to have two parsers in the image. >> > > Maybe this was a mistakeâ¦ > > Marcus

Feb. 6, 2015

Re: [Pharo-dev] ||

by Frank Shearar

On 5 February 2015 at 21:20, Thierry Goubier <thierry.goubier(a)gmail.com> wrote: > > > 2015-02-05 21:28 GMT+01:00 Eliot Miranda <eliot.miranda(a)gmail.com>: >> >> >> >> On Thu, Feb 5, 2015 at 11:34 AM, Thierry Goubier >> <thierry.goubier(a)gmail.com> wrote: >>> >>> >>> >>> 2015-02-05 18:51 GMT+01:00 Eliot Miranda <eliot.miranda(a)gmail.com>: >>>> >>>> >>>> >>>> On Thu, Feb 5, 2015 at 2:31 AM, Thierry Goubier >>>> <thierry.goubier(a)gmail.com> wrote: >>>>> >>>>> >>>>> >>>>> 2015-02-05 10:55 GMT+01:00 Sven Van Caekenberghe <sven(a)stfx.eu>: >>>>>> >>>>>> It is obviously a compromise (or a continuum) between abstractions and >>>>>> performance. >>>>> >>>>> >>>>> I agree. With a special view in that we are in a sub domain where >>>>> simple things well designed (Smalltalk, that is) are amazingly good at >>>>> supporting complex designs. >>>>> >>>>>> >>>>>> >>>>>> But there should remain a focus on efficiency (not just speed but also >>>>>> memory), it is hard to fix these things years later. >>>>> >>>>> >>>>> And I like the fact that efficient code and design is often a pleasure >>>>> to read and learn from :) >>>>> >>>>> Now, being radical: could we get rid of pragmas ? The only reason I see >>>>> to them is that they allow extension by external packages, because we can't >>>>> have methods which belong to two protocols (*). >>>> >>>> >>>> They are a Smalltalk-centric way of adding arbitrary metadata to >>>> methods; Smalltalk-centric in that a pragma is a Message instance, may be >>>> queried for senders, performed, etc, and that it can be parsed using the >>>> standard compiler (they add no new syntax). They have been broadly used. >>>> IME they have simplified and reduced code where ever they have been used. >>>> They don't have to be there but they're a good thing. Why do you want to >>>> get rid of them? >>> >>> >>> Because the "they have simplified and reduced code where ever they have >>> been used" is wrong. I just have to give you a counter example: >> >> >> OK, the claim is too strong. But they /have/ simplified code in cases >> where they're appropriate. And I can cite several examples. >> >>> >>> >>> One of the uses of pragmas is associating methods containing Gui commands >>> or settings to specific objects. Based on an object inspected or selected, >>> you search among all its methods the ones containing a specific pragma (and >>> you order them by a parameter to that pragma, if you want), and you execute >>> that method to retrieve the objects you want (presentations, menu commands, >>> shortcuts, you name it, I use it :)). >>> >>> The code to do that is exactly as long as the one which, on the same >>> object, retrieve all methods under a certain protocol (the latter being >>> faster than the pragma one, to boot). >>> >>> Each method is one line longer ("the pragma"). >>> >>> Each such method usually has in its name a copy of the pragma >>> (gtInspectorXXX methods, I'm looking at you), because of course this is far >>> more user friendly to indicate its purpose in the method name than in only >>> the pragma. >>> >>> (There are two more arguments for the use of pragmas in that context, one >>> which has a direct counter-example, one which hasn't: ) >>> >>> Moreover, the semantic of pragmas is "interesting" to describe, and in >>> some cases, require a good amount of dark magic about a global object >>> listening to all methods changes and capturing (and executing) certain >>> methods in a vague relation about when this is going to happen, or being >>> triggered on specific system events (main menu rebuilding, anyone?). The >>> funny thing is to see that pattern visible on a profile when loading >>> packages (talk of a scalable approach). >> >> >> But triggering in the background happens for maintaining change sets, >> notifying other clients too. It's not as if pragmas introduced such >> triggering; that kind of triggering has been in use for a long time. And >> being able to reshape the GUI automatically is very useful. > > > I don't contest the possibilities, it's just that they add a significant > layer of complexity when non mastered (how many Pharo developpers know which > event you have to register to to receive all new methods notifications? Is > that documented in one of the books?), and that, except for using them as > <primitives> or for extensibility, I see other syntaxes and smalltalk code > which are simpler. > > A good example is that the pragma syntax is never included in the one page > Smalltalk syntax description :) > >> >> >>> >>> >>>> >>>> (and yes, I'm biassed) >>> >>> >>> Then you're the right person to give me counter arguments... >>> >>> (Now, I'd look differently at pragmas used for gradual typing and so >>> on... But even for something like FFI, I'd seriously prefer to have >>> Smalltalk calls to describe the call and its arguments than a kind of script >>> hidden inside pragmas, just for the discoverability and because it makes one >>> less idiom to deal with) >> >> >> Why? A good use of pragmas is to associate meta data with a particular >> method. Having calls off to the side always introduces the need for >> book-keeping to keep those methods off to the side in sync with the methods >> they're describing. Typically everyone rolls their own. But here we're >> adding a level of triggering just to keep the metadata methods in sync. > > > I agree with the "metadata", but I'd prefer a executable, evaluate that > block as a medata literal than the pragma. Something that says > "onceAndStoreAsMetadata", to a block, for example. An API to compiled > methods which says add metadata. > > I strongly agree with your keep it in sync argument, still. Pragmas are > better than nothing. > >> >> >> There is no such need with pragmas; they are always in sync with the >> methods they describe because they are embedded in their methods. Instead >> we can use triggering to do useful things, adding a pane to open inspectors >> as soon as we define the method that describes the pane, adding or removing >> a menu entry, etc. > > > Just a naming convention does just that perfectly fine, and with less lines > (except for extensions by external packages) and faster code in many cases. > >> >> >> This is one idiom that covers a host of other cases. That's why I claim >> that whenever I've seen it used it has reduced complexity. >> >> Some history. Steve Dahl, I developed pragmas at ParcPlace, with Vassili >> Bykov adding abstractions for accessing them. The first step was to replace >> some ugly class-side code to set unwind bits in ensure: and ifCurtailed: by >> a pragma the compiler would recognise and set the bits itself. The first >> real use was to make the VisualWorks launcher's menus extensible. Before >> pragmas the launcher's menu was static and had lots of disabled entries for >> launching tools that were sold separately such as DLLAndCConnect. With >> pragmas the launcher's menu was defined with the base system's tools and >> then extended as each tool package was loaded, or cut-back as each tool was >> unloaded. So that decoupled the launcher from introducing new tools. A >> nice result. >> >> We then started using it for the browser and one could plug-in a single >> tool without redefining the browser's menu methods, which decoupled each >> extension. All this was done in the context of the parcel system, where we >> could rapidly load packages (parcels ~= Fuel). Pragmas allowed us to >> decouple these tools where they collided in places like menu definition, >> tool registration. >> >> Then Tami Lee, who was managing the COM connection that turned a VW image >> into a COM server, became the first "user" of pragmas outside of myself and >> Steve. She used it to replace a lot of class-side methods that defined the >> signatures of methods that comprised the server. It was a lovely clean-up. >> One could define the COM signature for a method in the method itself, and >> the class side lost about three separate methods that defined all that >> metadata. One could read the server method itself and understand its >> semantics without having to consult the class-side methods. One didn't have >> to know that there was metadata hidden on the class side because it was >> right there in your face. >> >> Then Vassili used it for his cool inspector framework, Trippy, which was >> similar to Glamour in some ways, and was a huge improvement over the old >> Inspector framework, again resulting in a much more pluggable, decoupled and >> extensible system. Vassili also added the abstractions for accessing >> pragmas in methods. >> >> Then we added checking so that one could restrict the compiler to accept >> only legal pragmas for a given class. But if we defined the legal pragmas >> in a class-side method, say legalPragmas, then this would be exactly the >> kind of single point for extensions that causes collisions between packages, >> each of which might want to add its own set of pragmas. The solution... use >> a pragma to mark a class-side method as defining a set of legal pragmas for >> a class. One could have more than one method defining a set of legal >> pragmas; packages wishing to add their own cool pragmas were decoupled. >> Once the system because recursive, it had to be a good idea ;-). > > > Ok, I start to see where the abstraction wasn't working so well... since > pragmas are not executed, when writing a method you can't know if the pragma > is correct, because even executing the method may not trigger the pragma > induced code. So you need the legalPragmas to give metadata on metadata for > the compiler to do a bit of static checking, but it doesn't work for > system-wide pragmas unless you extend Object :( > > And often it doesn't matter if the pragma reference a completely non > existent method or api, since it is probably never executed by anybody (and > if it is, it won't probably reify the error message properly as a > compilation error as it should, because it may be triggered miles away from > the system browser). Pragmas don't execute. They're _data_. There is no "calls unknown sender" because the don't execute. Eliot's point is that pragmas _describe_, and then other systems act on those descriptions. They're just like Java or C# attributes, or Python decorators. Only they're better, because Java/C# attributes can do anything, whereas pragmas merely describe. frank >> There are other uses; you've seen them. I used them in VMMaker to >> eliminate metadata that was embedded as sends to methods defined as ^self >> that Slang had to extract and analyse, and filter-out from generated code. >> They simplified Slang's code anaylsis, made the simulator more efficient >> (since there were no longer sends to execute). My point is that in all the >> cases I've seen, using pragmas has >> - simplified the code >> - made it obvious that methods have metadata associated with them >> - replaced specialized ways of associating metadata with code by the >> general pragma mechanism >> and in many of the cases it has >> - provided a more decoupled system >> - provided a more dynamic and extensible system > > > Yes, and I can point out some of its shortcomings: it's non-obvious, it's > limited, tools, even that many years later don't support them well (in > Squeak or Pharo, at least), its redundant in quite a few variants. > > Please, could we improve a bit? Methods belonging to multiple protocols > would give us the same decoupling as pragmas, and I would be free to avoid > them where I shouldn't have to use them :) > >> >> >> I've been meaning to write up the history of pragmas for ages, but >> Vassili, Steve or I have always been too busy. I think a community paper on >> their use and history would be worth-while, and might go a long way to >> reduce antipathies like yours. I will forever be in debt to anyone who >> wants to volunteer to help me write such a paper. > > > That would certainly be interesting :) > >> >> >>> >>> >>> Thierry >>> >>> (Look. I started using Smalltalk in 1992... and up to your description, I >>> wasn't aware pragmas were supposed to follow message syntax ;) Thanks for >>> the explanation, by the way) >> >> >> They /have/ to follow literal message syntax. t's all the compiler will >> accept. That's why there needs to be a paper. > > > Yes! > > Thanks for taking the time to argument, > > Thierry > >> >> >> >> -- >> best, >> Eliot

Feb. 6, 2015

Re: [Pharo-dev] Switching to Pharo from Visualworks

by Jan Vrany

On Fri, 2015-02-06 at 10:47 +0100, Markus Fritsche wrote: > > On 06.02.2015 09:33, stepharo wrote: > > > In the coming months we will work on putting in place our > > bootstrapping kernel. > > There are no Smalltalk able to do that right now. > > GNU Smalltalk does just that, if it doesn't find an image, it will be > bootstrapped by using the shipped .st fileouts. Smalltalk/X does that too. It does not even need .st fileouts at bootstrapping time to come up without an image. Jan > > A bit of cheating is involved, a compiler & initialization is > implemented on the VM side. > > So I would say "there are no Smalltalk that are able to do that right > now the way we want to do it" :-P > > (Pissing at the door contest, to refer to another unquoted > metaphor :-D)

Feb. 6, 2015

Re: [Pharo-dev] [Pharo-users] spotter preview

by Laurent

Hi, I really like Spotter. The preview feature makes me think that would be useful to have it in code completion. So often I use the wrong method because completion does not display class name. The ability to have code preview in code completion (and maybe class hierarchy too) would make me open far less browser I think. An easy first step may be that when I type Shift+enter to open Spotter it copies the word where the cursor is placed in a text editor in the Spotter search field. Cheers, Laurent Le lun. 2 fÃ©vr. 2015 Ã 22:02, Tudor Girba <tudor(a)tudorgirba.com> a Ã©crit : > Hi, > > The Glamorous Team is happy to present a new feature in Spotter: > preview (you toggle it with Cmd+p). We think this boosts the > usefulness of the Spotter interface significantly. > > > > For more details, please take a look at: > http://www.humane-assessment.com/blog/boosting-gtspotter-with-preview > > This is available in the Moose image, and it will soon be integrated > in the Pharo one. > > Please let us know what you think. > > Cheers, > Doru > > > -- > www.tudorgirba.com > > "Every thing has its own flow"

Feb. 6, 2015

Re: [Pharo-dev] Switching to Pharo from Visualworks

by Markus Fritsche

On 06.02.2015 10:52, Guillermo Polito wrote: > Well, but imagine how complex that bootstrap becomes when you want to > add to your classes: > > - traits > - layouts > - slots > ... > > And expressing all that in C also :) I don't want to imply it's easy. I once tried to decompose a squeak image, serialize the contents and then try to create a new working environment from that. I finaly gave up when I got { "One step forth", "Two steps forth", "One step back", "Two steps back"}* in any number of combinations... The image is a a) crafted artefact, not a b) generated one, but I think pharo is on a good path from a => b.

Feb. 6, 2015

Re: [Pharo-dev] ||

by Thierry Goubier

Hi Eliot, maybe I'll frame the core question a bit differently, thanks to your explanations. I see pragmas used mainly for two things: 1- expressing a link to some metadata used by low level tools: compiler, C lang generator, etc... primitives for me are part of that. Kind of neat to see that unified. 2- categorizing things in a decoupled, package-extension compatible way. I still think there is something in the design that bother me. 1- and 2- are convention-based, so as is most of Smalltalk anyway, so diregarding another approach to 2- as convention-based is a bit dishonest: pragmas get more authority because they look like they have been integrated in the language definition compared to competing solutions. No, this is just because I start to wonder if methods shouldn't have a bit more in that "define, add and manipulate" metadata idea, i.e. make it more explicit and start to have tools which represent methods as more like objects and not only text items (methods having metadata, additional slots or instance variables, counters, statistics, ast, traces, break points, etc...). And, in a way, a need to have two levels of execution: one which happens at compile time (i.e. when one accept a method), one which happens at runtime. For that, I think pragmas are a start, but they are not the complete answer. And I think we should solve the package-extension compatible thing in 2- to not have 2- (which is just for me a plain categorisation issue) polluting the design by introducing additional/unrelated requirements. 2015-02-05 22:47 GMT+01:00 Eliot Miranda <eliot.miranda(a)gmail.com>: > Hi Thierry, > > A block is far more difficult to deal with than a pragma. A pragma has a > simple key, its selector, and simple access to its arameters, the > arguments. A block is opaque. Essentially it can only be executable. > Pragmas are both executable and function as annotations. > Pragmas are executable, but in a context which is not visible at the place they are written. > > > >> I strongly agree with your keep it in sync argument, still. Pragmas are >> better than nothing. >> >>> >>> >>> There is no such need with pragmas; they are always in sync with the >>> methods they describe because they are embedded in their methods. Instead >>> we can use triggering to do useful things, adding a pane to open inspectors >>> as soon as we define the method that describes the pane, adding or removing >>> a menu entry, etc. >>> >> >> Just a naming convention does just that perfectly fine, and with less >> lines (except for extensions by external packages) and faster code in many >> cases. >> > > Yes, but there end up being lots of naming conventions and they are > non-obvious. Whereas pragmas, because they are in-your-face in the methods > in question, don't need conventions. They just need documenting ;-). > They are still conventions which needs documentation. Pragmas are, in allmost all uses, indirections (i.e. a tag meaning something to a far away object), and the meaning associated to a pragma is, in every case, a roll-your-own solution. And they are clearly "in your face" :) > > > That's not necessarily true. Some pragmas do cause processing at compile > time. For example, an FFI signature pragma can be checked at > compile-time. But it's in keeping with smalltalk that type checking is not > performed at compile time in most cases, isn't it? Why should one require > that pragmas be semantically checked at compile time when normal SMalltalk > code isn't? At least one knows that the message instance the pragma is > compiled to is a valid object and *can* be performed. So pone does know at > least that the pragma is executable. Obviously whether that ability to be > executed only becomes potent with the right receiver. So any compiled > pragma as the potential to be usefully evaluated. > Ok, but its all fuzzy. It may be executed, but it may be not. It may send an error if incorrect, but it may fail silently. It may be executed at compile time, it may be executed sometime later triggered by the compilation, or it may be executed at runtime, as if it was normal code. And of course it may not be executed at all ... You see what I mean? > > And often it doesn't matter if the pragma reference a completely non >> existent method or api, since it is probably never executed by anybody (and >> if it is, it won't probably reify the error message properly as a >> compilation error as it should, because it may be triggered miles away from >> the system browser). >> > > > There is lots about Smalltalk that is non-obvious, about programming in > general that is non-obvious. I don't see that as a specific criticism of > pragmas. Once one knows the idiom it is easy to use; its wide-spread use > is evidence of that. And hopefully this conversation will help make it > more obvious :-). That it is limited is also not perhaps a useful > criticism. The issue is whether it is adequate. I think it is. A literal > message goes a long way. I'e not heard of complaints about limitations so > far. Do you have specific examples where pragmas are inadequate? The > tools /do/ support them. One can do senders and implementors in the > browser and see the methods that include them, and the implementors of > pragmas. browseAllSelect: will narrow down the search. There is an API > for programmatic use (pragmasDo: et al). > See [*][**] for the tools support. For me, pragmas, even in their definition, have serious semantic issues. If they were strictly, as you describe them, a metadata API access executed at compile time, then they would be a lot stronger. Make them sent at compile-time on the method object, and that would probably solve all the true arguments I have against them :) for example: <worldMenu> against <tagAndAnnounce: #worldMenu>; <tag: #gtInspectorExtension> instead of <gtInspectorExtension>, etc... (<tagAndAnnounce:> would gain a bit of performance, as well). Thierry [*] Searching a bit for menu pragmas in a Pharo image seems to return a bit of a mess. There is so many of them, all differents, and interestingly, this does not return the code triggered (or using) them, which makes discovery of what the pragma is used for (and its parameters) an 'interesting' problem. I suggest a task then: an illustrated sequence of how to search for the code triggering world menu addition of a new command, for someone which is new to Pharo ;) [**] even when used for categorisation, the API is prone to bugs, such as having a method without pragma overriding a superclass method with pragma because they have the same name.

Feb. 6, 2015

Re: [Pharo-dev] Switching to Pharo from Visualworks

by Guillermo Polito

Well, but imagine how complex that bootstrap becomes when you want to add to your classes: - traits - layouts - slots ... And expressing all that in C also :) El Fri Feb 06 2015 at 10:47:19 AM, Markus Fritsche <mfritsche(a)reauktion.de> escribiÃ³: > > On 06.02.2015 09:33, stepharo wrote: > > In the coming months we will work on putting in place our bootstrapping > kernel. > There are no Smalltalk able to do that right now. > > > GNU Smalltalk does just that, if it doesn't find an image, it will be > bootstrapped by using the shipped .st fileouts. > > A bit of cheating is involved, a compiler & initialization is implemented > on the VM side. > > So I would say "there are no Smalltalk that are able to do that right now > the way we want to do it" :-P > > (Pissing at the door contest, to refer to another unquoted metaphor :-D) >

Feb. 6, 2015

Re: [Pharo-dev] Switching to Pharo from Visualworks

by Markus Fritsche

On 06.02.2015 09:33, stepharo wrote: > In the coming months we will work on putting in place our > bootstrapping kernel. > There are no Smalltalk able to do that right now. GNU Smalltalk does just that, if it doesn't find an image, it will be bootstrapped by using the shipped .st fileouts. A bit of cheating is involved, a compiler & initialization is implemented on the VM side. So I would say "there are no Smalltalk that are able to do that right now the way we want to do it" :-P (Pissing at the door contest, to refer to another unquoted metaphor :-D)

Feb. 6, 2015

Re: [Pharo-dev] Switching to Pharo from Visualworks

by Marcus Denker

> >> Looking at Pharo, it appears to me to be suffering the same bloat issues as >> Squeak. > > Well if you say that it is that you are just looking at the tip of iceberg. > This is not for fun that we are massively working on cleaning dependencies and removing > wrong code or rewriting it. In the coming months we will work on putting in place our bootstrapping kernel. > There are no Smalltalk able to do that right now. Bootstrapping means a lot in term of quality. > But we have some work to get there and we are busy with our real work (publishing papers). > I think the problem is that people always look at an artefact as âthis what they wantâ as opposed to âthis is just an imperfect snapshot of steps towards what we wantâ. e.g. Morphic still is a *mess*. We have some things started (e.g. Anthens) that will, when they are finished, allow us to simplify things. But right now they are just duplication. Some of the things are just âscaffoldingâ for better solutions in the future. So Pharo4 is just a snapshot of a tiny increment. Pharo5 will be another. And so on. One thing one needs to see is that only the things that are done are done. This is sometimes to exhausting: even the most trivial, obvious thing needs someone to actually do it. Marcus

Feb. 6, 2015