January 2015 - Pharo-users - lists.pharo.org

Re: [Pharo-users] How to subclass Float class

by stepharo

Hilaire you have also acancagua that support unit and conversion and aconcagua came out of a project dealing with money and trades. http://sdmeta.gforge.inria.fr/Teaching/CoursAnnecy/0506-M1-COO/ read the two articles in there. Stef Le 11/1/15 11:22, Hilaire a Ã©crit : > Joachim, > > Thanks for the tips. > I saw the Unit package was following the same pattern you are describing. > My first though was to use ScaledDecimal, but I discovered it is pretty > slow with computation (amortization schedule, search for rate) but there > are workarounds for that. > > Hilaire > > Le 11/01/2015 10:36, Joachim Tuchel a Ã©crit : >> There are more arguments against Subclassing any Number class: >> >> Exchange rates are two-way most of the times. It is not only USD->EUR, >> but also the other way round. This is not the responsibilty of a number. >> >> For more information, I recommend Martin Fowler's Analysis Patterns book >> (old, but not dated at all!). >> >> Joachim >> >> >> Am 11.01.15 um 10:31 schrieb Joachim Tuchel: >>> Ah, I just saw on second reading that you want to implement something >>> for currency exchange rates, not MonetaryAmounts. Still, don't use >>> Float, use ScaledDecimal or FixedPoint and make sure it NEVER contains >>> a Float. You'll get into all kinds of strange problems, starting with >>> Imports from datasources like Yahoo or whatever. >>> >>> I'd subclass Object, and make the new class hold the exchange rates as >>> a ScaledDecimal with a well-defined scale (like 4 or 6 or even 8 >>> digits if you want). >>> >>> Joachim >>> >>> >>> >>> >>> Am 11.01.15 um 10:28 schrieb Joachim Tuchel: >>>> Hilaire, >>>> >>>> unless you have very (very very) specific needs, I would strongly >>>> discourage you to use Float for anything related to Money or >>>> Percentages. >>>> >>>> We use a subclass of Object for MonetaryAmounts and implemented most >>>> of the protocol of Magnitude. But, most importantly, the amount >>>> instVar is made sure to always hold instances of ScaledDecimal (in VA >>>> Smalltalk, that is). >>>> >>>> Joachim >>>> >>>> Am 11.01.15 um 10:25 schrieb Hilaire: >>>>> Le 11/01/2015 09:06, stepharo a Ã©crit : >>>>>> Hilaire >>>>>> >>>>>> what is your requirement? >>>>>> >>>>>> Stef >>>>> I want to create a currency object, basically a Float with an attribute >>>>> to specify the currency unit. >>>>> >>>>> Hilaire >>>>> >>>>> >>>> >>>> >>> >>> >> >> >

Jan. 11, 2015

Re: [Pharo-users] How to subclass Float class

by Hilaire

Joachim, Thanks for the tips. I saw the Unit package was following the same pattern you are describing. My first though was to use ScaledDecimal, but I discovered it is pretty slow with computation (amortization schedule, search for rate) but there are workarounds for that. Hilaire Le 11/01/2015 10:36, Joachim Tuchel a Ã©crit : > There are more arguments against Subclassing any Number class: > > Exchange rates are two-way most of the times. It is not only USD->EUR, > but also the other way round. This is not the responsibilty of a number. > > For more information, I recommend Martin Fowler's Analysis Patterns book > (old, but not dated at all!). > > Joachim > > > Am 11.01.15 um 10:31 schrieb Joachim Tuchel: >> Ah, I just saw on second reading that you want to implement something >> for currency exchange rates, not MonetaryAmounts. Still, don't use >> Float, use ScaledDecimal or FixedPoint and make sure it NEVER contains >> a Float. You'll get into all kinds of strange problems, starting with >> Imports from datasources like Yahoo or whatever. >> >> I'd subclass Object, and make the new class hold the exchange rates as >> a ScaledDecimal with a well-defined scale (like 4 or 6 or even 8 >> digits if you want). >> >> Joachim >> >> >> >> >> Am 11.01.15 um 10:28 schrieb Joachim Tuchel: >>> Hilaire, >>> >>> unless you have very (very very) specific needs, I would strongly >>> discourage you to use Float for anything related to Money or >>> Percentages. >>> >>> We use a subclass of Object for MonetaryAmounts and implemented most >>> of the protocol of Magnitude. But, most importantly, the amount >>> instVar is made sure to always hold instances of ScaledDecimal (in VA >>> Smalltalk, that is). >>> >>> Joachim >>> >>> Am 11.01.15 um 10:25 schrieb Hilaire: >>>> Le 11/01/2015 09:06, stepharo a Ã©crit : >>>>> Hilaire >>>>> >>>>> what is your requirement? >>>>> >>>>> Stef >>>> >>>> I want to create a currency object, basically a Float with an attribute >>>> to specify the currency unit. >>>> >>>> Hilaire >>>> >>>> >>> >>> >>> >> >> >> > > > -- Dr. Geo - http://drgeo.eu iStoa - http://istoa.drgeo.eu

Jan. 11, 2015

Re: [Pharo-users] How to subclass Float class

by Joachim Tuchel

There are more arguments against Subclassing any Number class: Exchange rates are two-way most of the times. It is not only USD->EUR, but also the other way round. This is not the responsibilty of a number. For more information, I recommend Martin Fowler's Analysis Patterns book (old, but not dated at all!). Joachim Am 11.01.15 um 10:31 schrieb Joachim Tuchel: > Ah, I just saw on second reading that you want to implement something > for currency exchange rates, not MonetaryAmounts. Still, don't use > Float, use ScaledDecimal or FixedPoint and make sure it NEVER contains > a Float. You'll get into all kinds of strange problems, starting with > Imports from datasources like Yahoo or whatever. > > I'd subclass Object, and make the new class hold the exchange rates as > a ScaledDecimal with a well-defined scale (like 4 or 6 or even 8 > digits if you want). > > Joachim > > > > > Am 11.01.15 um 10:28 schrieb Joachim Tuchel: >> Hilaire, >> >> unless you have very (very very) specific needs, I would strongly >> discourage you to use Float for anything related to Money or >> Percentages. >> >> We use a subclass of Object for MonetaryAmounts and implemented most >> of the protocol of Magnitude. But, most importantly, the amount >> instVar is made sure to always hold instances of ScaledDecimal (in VA >> Smalltalk, that is). >> >> Joachim >> >> Am 11.01.15 um 10:25 schrieb Hilaire: >>> Le 11/01/2015 09:06, stepharo a Ã©crit : >>>> Hilaire >>>> >>>> what is your requirement? >>>> >>>> Stef >>> >>> I want to create a currency object, basically a Float with an attribute >>> to specify the currency unit. >>> >>> Hilaire >>> >>> >> >> >> > > >

Jan. 11, 2015

Re: [Pharo-users] How to subclass Float class

by Joachim Tuchel

Ah, I just saw on second reading that you want to implement something for currency exchange rates, not MonetaryAmounts. Still, don't use Float, use ScaledDecimal or FixedPoint and make sure it NEVER contains a Float. You'll get into all kinds of strange problems, starting with Imports from datasources like Yahoo or whatever. I'd subclass Object, and make the new class hold the exchange rates as a ScaledDecimal with a well-defined scale (like 4 or 6 or even 8 digits if you want). Joachim Am 11.01.15 um 10:28 schrieb Joachim Tuchel: > Hilaire, > > unless you have very (very very) specific needs, I would strongly > discourage you to use Float for anything related to Money or Percentages. > > We use a subclass of Object for MonetaryAmounts and implemented most > of the protocol of Magnitude. But, most importantly, the amount > instVar is made sure to always hold instances of ScaledDecimal (in VA > Smalltalk, that is). > > Joachim > > Am 11.01.15 um 10:25 schrieb Hilaire: >> Le 11/01/2015 09:06, stepharo a Ã©crit : >>> Hilaire >>> >>> what is your requirement? >>> >>> Stef >> >> I want to create a currency object, basically a Float with an attribute >> to specify the currency unit. >> >> Hilaire >> >> > > >

Jan. 11, 2015

Re: [Pharo-users] How to subclass Float class

by Joachim Tuchel

Hilaire, unless you have very (very very) specific needs, I would strongly discourage you to use Float for anything related to Money or Percentages. We use a subclass of Object for MonetaryAmounts and implemented most of the protocol of Magnitude. But, most importantly, the amount instVar is made sure to always hold instances of ScaledDecimal (in VA Smalltalk, that is). Joachim Am 11.01.15 um 10:25 schrieb Hilaire: > Le 11/01/2015 09:06, stepharo a Ã©crit : >> Hilaire >> >> what is your requirement? >> >> Stef > > I want to create a currency object, basically a Float with an attribute > to specify the currency unit. > > Hilaire > >

Jan. 11, 2015

Re: [Pharo-users] How to subclass Float class

by Hilaire

Le 11/01/2015 09:06, stepharo a Ã©crit : > Hilaire > > what is your requirement? > > Stef I want to create a currency object, basically a Float with an attribute to specify the currency unit. Hilaire -- Dr. Geo - http://drgeo.eu iStoa - http://istoa.drgeo.eu

Jan. 11, 2015

Re: [Pharo-users] Problem due to deprecation of class Url in Pharo 3 and Moose 5.0

by stepharo

>> Yes change the code of the Parser not to use old code. > As I pointed out, the Parser is a large and complex package, and I am not > the author, so this is easier said than done. I'm dealing daily with code having the same characteristics. > It seems a bit odd to dismiss > code which worked OK in Moose 4.9, but not in Moose 5.0, as 'old code.' I do not know what happened between 4.9 and 5.0 but if this is between pharo30 and pharo40 => one full year of efforts (you know many people improving things and putting energy in the system). And be ready because we will remove URL old class. Now the good aspect is that you are lucky (we are all lucky) that sven is improving constantly Zinc. But there is no such world were unmaintained packages would indefinitively work while the world is changing. > It > is code which has no functional equivalent in the new code, as Sven has > confirmed. Then it means that you have to cooperate with sven to get Zinc improved. And feel lucky you can. The overall process may look frustrating but a system that is not changing is See law of software evolution (1974) "Continuing Change" â an E-type system must be continually adapted or it becomes progressively less satisfactory[3] http://en.wikipedia.org/wiki/Lehman's_laws_of_software_evolution > > Thanks again > > Peter Kenny > > -----Original Message----- > From: Pharo-users [mailto:pharo-users-bounces@lists.pharo.org] On Behalf Of > Sven Van Caekenberghe > Sent: 10 January 2015 16:36 > To: Any question about pharo is welcome > Subject: Re: [Pharo-users] Problem due to deprecation of class Url in Pharo > 3 and Moose 5.0 > > >> On 10 Jan 2015, at 16:45, stepharo <stepharo(a)free.fr> wrote: >> >> >> Le 10/1/15 11:41, PBKResearch a Ã©crit : >>> Hello >>> >>> I have run into a problem in moving some existing work from earlier > versions of Pharo/Moose. I have found a work around, but I wonder if there > is a tidier way of handling it. >>> >>> I make frequent use of Todd Blanchardâs HTML parser and validator, HTMCSS > (http://smalltalkhub.com/#!/~ToddBlanchard/HTMCSSValidatingParser) which > was originally written for Squeak but has performed without trouble on > earlier versions of Pharo. When I try to use it on Moose 5.0, I get frequent > warning messages about Url being deprecated. I have made the problem go away > by commenting out the deprecation warning in Url class>>new, but I wonder > what should be done on a more permanent basis. >> Yes change the code of the Parser not to use old code. >>> The problem arises because HTMCSS does not just parse the original HTML > file; it also loads and parses any referenced CSS files. (This is a function > I could do without, but I donât fancy trying surgery on a complex package > where I only partly understand the workings!) It constructs the full address > of the CSS file by combining the root address of the HTML with the relative > address of the CSS, using Url class>>combine:withRelative:, and in the > course of this it invokes Url class>>new; hence the deprecation message. >> use ZnURL >>> The deprecation message says Url has been replaced by ZnUrl, but this is > clearly not a simple replacement of one message by an equivalent; there is > no ZnUrl class>>combine:withRelative:, for instance. >> Sven will certainly comment but I guess that there is certainly the same > behavior. > > ZnUrl>>#inContextOf: is the selector you are looking for, but path merging > is not supported (yet). > > 'readme.txt' asZnUrl inContextOf: 'http://www.host.com:8080' asZnUrl. > > Maybe we should add path merging, I'll think about it. > >>> The tidiest solution would no doubt be to find an equivalent method in > Zinc, which I am sure exists, and then modify the HTMCSS code to use it. I > have tried to find an equivalent, but Zinc is a large and complex system and > I rapidly got lost. >> It should be in ZnURL >> >> is it not addPathSegment:? >> >> >> from class comment >> >> ZnUrl new >> scheme: #https; >> host: 'encrypted.google.com'; >> addPathSegment: 'search'; >> queryAt: 'q' put: 'Smalltalk'; >> yourself. >> >> host: looks like the root >> addPathSegment: looks like https://encrypted.google.com/search >> >>> >>> I wonder more broadly about the strategy of deprecating functions which > are required by legacy packages, as in this case. Should there at least be a > way of overriding deprecations? (I suppose that is what I have done by > commenting it out, but it seems crude.) > > This is how you can work around Deprecation warnings: > > [ Url combine: 'http://www.foo.com/one/two/' withRelative: 'bar/readme.txt' > ] > on: Deprecation do: [ :exception | exception resume ] > > but that is a temporary hack. > >>> Thanks in advance for any help or suggestions. >>> >>> Peter Kenny > Sven > > > > >

Jan. 11, 2015

Re: [Pharo-users] How to subclass Float class

by stepharo

Hilaire what is your requirement? Stef Le 10/1/15 22:52, Hilaire a Ã©crit : > It looks like when I want to create a subclass of Float, I have this odd > class creation message. Moreoever, I can add instance variable to this > new class: when compiling there are wipe out: argument > instanceVariableNames: '' remain empty. > > If I change Float to Object, all get back to normal. > > Why is it like this ? > > > Float variableWordSubclass: #MyClass > instanceVariableNames: '' > classVariableNames: '' > category: 'Cofigest-Financial' > > > Thanks > > Hilaire >

Jan. 11, 2015

Re: [Pharo-users] Problem due to deprecation of class Url in Pharo 3 and Moose 5.0

by Sven Van Caekenberghe

Peter, > On 10 Jan 2015, at 23:30, PBKResearch <peter(a)pbkresearch.co.uk> wrote: > >> Yes change the code of the Parser not to use old code. > As I pointed out, the Parser is a large and complex package, and I am not > the author, so this is easier said than done. It seems a bit odd to dismiss > code which worked OK in Moose 4.9, but not in Moose 5.0, as 'old code.' It > is code which has no functional equivalent in the new code, as Sven has > confirmed. Could you explain what arguments were given to the combine and what the expected output was/should be ? How does it use path merging ? Thx, Sven

Jan. 10, 2015

Re: [Pharo-users] Problem due to deprecation of class Url in Pharo 3 and Moose 5.0

by PBKResearch

Sven: Thanks for the suggestions. I have tried ZnUrl>>#inContextOf:, but it does not produce the correct address; evidently I shall have to wait until you have full path merging implemented. Meanwhile, I have used your 'temporary hack' to ignore the deprecation; it is at least not as hackish as my approach. Stepharo: > Yes change the code of the Parser not to use old code. As I pointed out, the Parser is a large and complex package, and I am not the author, so this is easier said than done. It seems a bit odd to dismiss code which worked OK in Moose 4.9, but not in Moose 5.0, as 'old code.' It is code which has no functional equivalent in the new code, as Sven has confirmed. Thanks again Peter Kenny -----Original Message----- From: Pharo-users [mailto:pharo-users-bounces@lists.pharo.org] On Behalf Of Sven Van Caekenberghe Sent: 10 January 2015 16:36 To: Any question about pharo is welcome Subject: Re: [Pharo-users] Problem due to deprecation of class Url in Pharo 3 and Moose 5.0 > On 10 Jan 2015, at 16:45, stepharo <stepharo(a)free.fr> wrote: > > > Le 10/1/15 11:41, PBKResearch a Ã©crit : >> Hello >> >> I have run into a problem in moving some existing work from earlier versions of Pharo/Moose. I have found a work around, but I wonder if there is a tidier way of handling it. >> >> I make frequent use of Todd BlanchardÂs HTML parser and validator, HTMCSS (http://smalltalkhub.com/#!/~ToddBlanchard/HTMCSSValidatingParser) which was originally written for Squeak but has performed without trouble on earlier versions of Pharo. When I try to use it on Moose 5.0, I get frequent warning messages about Url being deprecated. I have made the problem go away by commenting out the deprecation warning in Url class>>new, but I wonder what should be done on a more permanent basis. > Yes change the code of the Parser not to use old code. >> >> The problem arises because HTMCSS does not just parse the original HTML file; it also loads and parses any referenced CSS files. (This is a function I could do without, but I donÂt fancy trying surgery on a complex package where I only partly understand the workings!) It constructs the full address of the CSS file by combining the root address of the HTML with the relative address of the CSS, using Url class>>combine:withRelative:, and in the course of this it invokes Url class>>new; hence the deprecation message. > > use ZnURL >> >> The deprecation message says Url has been replaced by ZnUrl, but this is clearly not a simple replacement of one message by an equivalent; there is no ZnUrl class>>combine:withRelative:, for instance. > Sven will certainly comment but I guess that there is certainly the same behavior. ZnUrl>>#inContextOf: is the selector you are looking for, but path merging is not supported (yet). 'readme.txt' asZnUrl inContextOf: 'http://www.host.com:8080' asZnUrl. Maybe we should add path merging, I'll think about it. >> The tidiest solution would no doubt be to find an equivalent method in Zinc, which I am sure exists, and then modify the HTMCSS code to use it. I have tried to find an equivalent, but Zinc is a large and complex system and I rapidly got lost. > It should be in ZnURL > > is it not addPathSegment:? > > > from class comment > > ZnUrl new > scheme: #https; > host: 'encrypted.google.com'; > addPathSegment: 'search'; > queryAt: 'q' put: 'Smalltalk'; > yourself. > > host: looks like the root > addPathSegment: looks like https://encrypted.google.com/search > >> >> I wonder more broadly about the strategy of deprecating functions which are required by legacy packages, as in this case. Should there at least be a way of overriding deprecations? (I suppose that is what I have done by commenting it out, but it seems crude.) This is how you can work around Deprecation warnings: [ Url combine: 'http://www.foo.com/one/two/' withRelative: 'bar/readme.txt' ] on: Deprecation do: [ :exception | exception resume ] but that is a temporary hack. >> Thanks in advance for any help or suggestions. >> >> Peter Kenny > Sven

Jan. 10, 2015