August 2017 - Pharo-users - lists.pharo.org

Re: [Pharo-users] Lazy-initialization patterns

by Esteban A. Maringolo

2017-08-05 19:21 GMT-03:00 Peter Uhnak <i.uhnak(a)gmail.com>: > If I want to initialize the value in a separate method (typically for testing or reuse), then I prefer to avoid state mutation there and instead I return the result. > > MyClass>>#property > ^ property ifNil: [ property := self createNewProperty ] > > MyClass>>createNewProperty > "I won't touch property instance variable here, just create a new value and return it" > ^ self bar collect: [ :e | e drink ] > > > > an initializationMethod returning the value instead of the receiver is a code smell to me. > > For this reason I tend to name such methods createNewX, initializeX says to me "only mutate state and return self" I like this approach very much, it makes the accessor code concise and separates the implementation of the property creation. Thank you! Esteban A. Maringolo

Aug. 5, 2017

Re: [Pharo-users] Lazy-initialization patterns

by Esteban A. Maringolo

I know the compiler is smart enough in most cases, and even if it isn't, an extra send or two won't hurt me in the kind of computation I do. But it's the style what "worried" me the most. Let's use the first then :) Esteban A. Maringolo 2017-08-05 19:18 GMT-03:00 Paul DeBruicker <pdebruic(a)gmail.com>: > Seems like either way would have unmeasurable performance impact for your > application vs the other and you should go for whats most > legible/comprehensible. > > > On that metric I prefer the first but #yolo > > > > > > > > Esteban A. Maringolo wrote > > Hi there, > > > > I have a question about lazy initialization accessor methods that always > > keep me thinking in terms of performance and style. > > > > For years I did something like: > > > > MyClass>>#property > > property isNil ifTrue: [ self initializeProperty ]. "It could be ifNil: > > as well" > > ^property > > > > MyClass>>#initializeProperty > > "Returns the receiver, not the property." > > property := self foo collect: [:e | ... ]. > > > > > > But this made me think that maybe I'm performing extra operations, so I > > started doing something like: > > > > MyClass>>#property > > ^property ifNil: [ self initializeProperty ] > > > > MyClass>>#initializeProperty > > ^property := self foo collect: [:e | ... ] > > > > The initialize method is often created by an "Extract Method" refactoring > > I > > do in the accesor, where I do the initial implementation. > > > > > > The messages makes me think that the second implementation is "faster", > > but > > an initializationMethod returning the value instead of the receiver is a > > code smell to me. > > > > I early initialize everything I know will be be used right away, but for > > cases it doesn't make sense. > > > > > > What do you think/prefer? Why? > > > > Maybe we could use the reified variables (slots) to implement the lazy > > initialization themselves :) > > > > > > Best regards! > > > > Esteban A. Maringolo > > > > > > -- > View this message in context: http://forum.world.st/Lazy- > initialization-patterns-tp4958897p4958901.html > Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com. > >

Aug. 5, 2017

Re: [Pharo-users] Lazy-initialization patterns

by Peter Uhnak

Personally I prever to avoid long lazy initializations, so I have it nice and tidy in a single method. MyClass>>#property ^ property ifNil: [ property := self bar collect: #food ] If I want to initialize the value in a separate method (typically for testing or reuse), then I prefer to avoid state mutation there and instead I return the result. MyClass>>#property ^ property ifNil: [ property := self createNewProperty ] MyClass>>createNewProperty "I won't touch property instance variable here, just create a new value and return it" ^ self bar collect: [ :e | e drink ] > an initializationMethod returning the value instead of the receiver is a code smell to me. For this reason I tend to name such methods createNewX, initializeX says to me "only mutate state and return self" Peter

Aug. 5, 2017

Re: [Pharo-users] Glorp: `session login` fails for Garage SQLite

by Herby VojÄÃk

Esteban A. Maringolo wrote: > Herby, > > I regularly use `session login`, but I don't use SQLite in Pharo, but I > do in VisualWorks and it works just fine. > Maybe if there is a bug we should fix it. Even with a no-op method. > > Regards! > > Esteban A. Maringolo It's hard. The problem is PharoDatabaseAccessor >> encoding ^self connection queryEncoding which overrides parent, which is atm: encoding "The connection is specific to the dialect; some dialects will need to override this method." ^connection encoding The former was added at GuillermoPolito.73 back in 2011 (and the latter was the same back then). It probably fixed something, but I don't see any implementors of queryEncoding atm (definitely not in Garage). From the diff it is clear lots of databases and drivers have gone. Now, why was it change for Pharo (and does it need to be changed in 2017)? Ccing Guillermo Polito. Herby P.S.: I wonder how it is that no one actually had problem with this? This predictably fails on `session login` on pharo, unless queryEncoding is somehow magically present without seeing it in source code for other platforms? > > 2017-08-05 15:52 GMT-03:00 Herby VojÄÃk <herby(a)mailbox.sk > <mailto:herby@mailbox.sk>>: > > Alistair Grant wrote: > > Hi Herby, > > On 5 August 2017 at 18:09, Herby VojÄÃk<herby(a)mailbox.sk > <mailto:herby@mailbox.sk>> wrote: > > Hello! > > First of all, what is preferred way to (first time) login > into database? I > had the impression that `aDatabaseAccessor login` is sorta > low-level, and > one should do `session login` (after all, it is session you > get to work > with, not an accessor). > > But with Garage SQLite, `session login`, when accessor is > not logged, always > fails with "MessageNotUnderstood: > GASqlite3Driver>>queryEncoding". > > Should one not use `session login` at all, then (when > accessor is logged, it > just does nothing, if it isn't, it connects the accessor, > but tries to do > some additional work which always fails)? > > Herby > > > From memory this is caused by differences between VisualWorks > and Pharo. > > Anyway, it is discussed and resolved in: > > http://forum.world.st/Glorp-SQLite3-issue-td4899792.html > <http://forum.world.st/Glorp-SQLite3-issue-td4899792.html> > > > Doesn't look like solved to me. Anyway, at least I know it is known > for year and no-one seemed to see it as a bug. > > I think it is one (you cannot just send queryEncoding where no class > implements it and be fine, imo). > > So what is the state of `session login`? Is it meant to be used, or > everyone just took a step down to low-level and uses `accessor > login` instead? :-( > > > Cheers, > Alistair > > > Thanks, Herby > >

Aug. 5, 2017

Re: [Pharo-users] Lazy-initialization patterns

by Paul DeBruicker

Seems like either way would have unmeasurable performance impact for your application vs the other and you should go for whats most legible/comprehensible. On that metric I prefer the first but #yolo Esteban A. Maringolo wrote > Hi there, > > I have a question about lazy initialization accessor methods that always > keep me thinking in terms of performance and style. > > For years I did something like: > > MyClass>>#property > property isNil ifTrue: [ self initializeProperty ]. "It could be ifNil: > as well" > ^property > > MyClass>>#initializeProperty > "Returns the receiver, not the property." > property := self foo collect: [:e | ... ]. > > > But this made me think that maybe I'm performing extra operations, so I > started doing something like: > > MyClass>>#property > ^property ifNil: [ self initializeProperty ] > > MyClass>>#initializeProperty > ^property := self foo collect: [:e | ... ] > > The initialize method is often created by an "Extract Method" refactoring > I > do in the accesor, where I do the initial implementation. > > > The messages makes me think that the second implementation is "faster", > but > an initializationMethod returning the value instead of the receiver is a > code smell to me. > > I early initialize everything I know will be be used right away, but for > cases it doesn't make sense. > > > What do you think/prefer? Why? > > Maybe we could use the reified variables (slots) to implement the lazy > initialization themselves :) > > > Best regards! > > Esteban A. Maringolo -- View this message in context: http://forum.world.st/Lazy-initialization-patterns-tp4958897p4958901.html Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.

Aug. 5, 2017

Re: [Pharo-users] PetitParser: Parse X as long as it's not Y

by Bernardo Ezequiel Contreras

did you try with negate? comment ^ ($" asParser , $" asParser negate star , $" asParser) flatten On Sat, Aug 5, 2017 at 5:26 PM, Sean P. DeNigris <sean(a)clipperadams.com> wrote: > How do I tell Petit Parser to parse a string of certain allowable > characters > as long as the final result isn't a particular string? E.g. consume an > identifier as long as it's not 'Baz' or 'Bar' > > Thanks > > > > ----- > Cheers, > Sean > -- > View this message in context: http://forum.world.st/ > PetitParser-Parse-X-as-long-as-it-s-not-Y-tp4958895.html > Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com. > > -- Bernardo E.C. Sent from a cheap desktop computer in South America.

Aug. 5, 2017

Lazy-initialization patterns

by Esteban A. Maringolo

Hi there, I have a question about lazy initialization accessor methods that always keep me thinking in terms of performance and style. For years I did something like: MyClass>>#property property isNil ifTrue: [ self initializeProperty ]. "It could be ifNil: as well" ^property MyClass>>#initializeProperty "Returns the receiver, not the property." property := self foo collect: [:e | ... ]. But this made me think that maybe I'm performing extra operations, so I started doing something like: MyClass>>#property ^property ifNil: [ self initializeProperty ] MyClass>>#initializeProperty ^property := self foo collect: [:e | ... ] The initialize method is often created by an "Extract Method" refactoring I do in the accesor, where I do the initial implementation. The messages makes me think that the second implementation is "faster", but an initializationMethod returning the value instead of the receiver is a code smell to me. I early initialize everything I know will be be used right away, but for cases it doesn't make sense. What do you think/prefer? Why? Maybe we could use the reified variables (slots) to implement the lazy initialization themselves :) Best regards! Esteban A. Maringolo

Aug. 5, 2017

Re: [Pharo-users] Glorp: `session login` fails for Garage SQLite

by Esteban A. Maringolo

Herby, I regularly use `session login`, but I don't use SQLite in Pharo, but I do in VisualWorks and it works just fine. Maybe if there is a bug we should fix it. Even with a no-op method. Regards! Esteban A. Maringolo 2017-08-05 15:52 GMT-03:00 Herby VojÄÃk <herby(a)mailbox.sk>: > Alistair Grant wrote: > >> Hi Herby, >> >> On 5 August 2017 at 18:09, Herby VojÄÃk<herby(a)mailbox.sk> wrote: >> >>> Hello! >>> >>> First of all, what is preferred way to (first time) login into database? >>> I >>> had the impression that `aDatabaseAccessor login` is sorta low-level, and >>> one should do `session login` (after all, it is session you get to work >>> with, not an accessor). >>> >>> But with Garage SQLite, `session login`, when accessor is not logged, >>> always >>> fails with "MessageNotUnderstood: GASqlite3Driver>>queryEncoding". >>> >>> Should one not use `session login` at all, then (when accessor is >>> logged, it >>> just does nothing, if it isn't, it connects the accessor, but tries to do >>> some additional work which always fails)? >>> >>> Herby >>> >> >> From memory this is caused by differences between VisualWorks and Pharo. >> >> Anyway, it is discussed and resolved in: >> >> http://forum.world.st/Glorp-SQLite3-issue-td4899792.html >> > > Doesn't look like solved to me. Anyway, at least I know it is known for > year and no-one seemed to see it as a bug. > > I think it is one (you cannot just send queryEncoding where no class > implements it and be fine, imo). > > So what is the state of `session login`? Is it meant to be used, or > everyone just took a step down to low-level and uses `accessor login` > instead? :-( > > >> Cheers, >> Alistair >> >> > Thanks, Herby > >

Aug. 5, 2017

PetitParser: Parse X as long as it's not Y

by Sean P. DeNigris

How do I tell Petit Parser to parse a string of certain allowable characters as long as the final result isn't a particular string? E.g. consume an identifier as long as it's not 'Baz' or 'Bar' Thanks ----- Cheers, Sean -- View this message in context: http://forum.world.st/PetitParser-Parse-X-as-long-as-it-s-not-Y-tp4958895.h… Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.

Aug. 5, 2017

Re: [Pharo-users] Glorp: `session login` fails for Garage SQLite

by Herby VojÄÃk

Alistair Grant wrote: > Hi Herby, > > On 5 August 2017 at 18:09, Herby VojÄÃk<herby(a)mailbox.sk> wrote: >> Hello! >> >> First of all, what is preferred way to (first time) login into database? I >> had the impression that `aDatabaseAccessor login` is sorta low-level, and >> one should do `session login` (after all, it is session you get to work >> with, not an accessor). >> >> But with Garage SQLite, `session login`, when accessor is not logged, always >> fails with "MessageNotUnderstood: GASqlite3Driver>>queryEncoding". >> >> Should one not use `session login` at all, then (when accessor is logged, it >> just does nothing, if it isn't, it connects the accessor, but tries to do >> some additional work which always fails)? >> >> Herby > > From memory this is caused by differences between VisualWorks and Pharo. > > Anyway, it is discussed and resolved in: > > http://forum.world.st/Glorp-SQLite3-issue-td4899792.html Doesn't look like solved to me. Anyway, at least I know it is known for year and no-one seemed to see it as a bug. I think it is one (you cannot just send queryEncoding where no class implements it and be fine, imo). So what is the state of `session login`? Is it meant to be used, or everyone just took a step down to low-level and uses `accessor login` instead? :-( > > Cheers, > Alistair > Thanks, Herby

Aug. 5, 2017