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Re: [Pharo-project] Issue 3986 in pharo: Bug with Delay during clock rollover

by pharo＠googlecode.com

Comment #3 on issue 3986 by marcus.d...(a)gmail.com: Bug with Delay during clock rollover http://code.google.com/p/pharo/issues/detail?id=3986 added to 13149 for testing

April 14, 2011

Re: [Pharo-project] isHealthy

by Henrik Sperre Johansen

On 14.04.2011 11:04, StÃ©phane Ducasse wrote: >>>>> Hi igor >>>>> >>>>> this is strange I have a dictionary whose array contains nil and still >>>>> isHealthy returns true. >>>>> can an array of a dictionary contains nil? >>>>> >>>> no, it can't . >>>> And how you end up with dictionary which having array = nil? During >>>> initialization, it allocates and initializes array, >>>> so, normally, there is no way how it could be nil. >>> Ehm, the array can _contain_ nil(the empty slot marker) (and it will in all >>> cases, if it's working correctly), it cannot _be_ nil though. >>> >>> isHealthy has nothing to do with this though, it checks if all elements >>> (non-nil entries in the array) are at positions which are valid. >>> \ >> Err.. maybe i misunderstood? >> >> i meant >> >> dict array == nil >> should not happen, but >> (dict array at: someindex ) == nil >> is quite normal. > I do not know I have a do: loop and some elements are nil and break the loop. > > Stef do: iterates the values in the Dictionary, and yes, it's perfectly valid to have a pair someKey -> nil in the dictionary. Why you have it (ie who put it there), and if it should be valid in your case, you'd have to figure out :) Cheers, Henry

April 14, 2011

Re: [Pharo-project] isHealthy

by StÃ©phane Ducasse

>>>> Hi igor >>>> >>>> this is strange I have a dictionary whose array contains nil and still >>>> isHealthy returns true. >>>> can an array of a dictionary contains nil? >>>> >>> no, it can't . >>> And how you end up with dictionary which having array = nil? During >>> initialization, it allocates and initializes array, >>> so, normally, there is no way how it could be nil. >> >> Ehm, the array can _contain_ nil(the empty slot marker) (and it will in all >> cases, if it's working correctly), it cannot _be_ nil though. >> >> isHealthy has nothing to do with this though, it checks if all elements >> (non-nil entries in the array) are at positions which are valid. >> \ > > Err.. maybe i misunderstood? > > i meant > > dict array == nil > should not happen, but > (dict array at: someindex ) == nil > is quite normal. I do not know I have a do: loop and some elements are nil and break the loop. Stef

April 14, 2011

[Pharo-project] Issue 4013 in pharo: DNU ObjectExlorer with taskbar enabled

by pharo＠googlecode.com

Status: Accepted Owner: marcus.d...(a)gmail.com New issue 4013 by marcus.d...(a)gmail.com: DNU ObjectExlorer with taskbar enabled http://code.google.com/p/pharo/issues/detail?id=4013 DNU ObjectExlorer with taskbar enabled #theme, same as Inspector

April 14, 2011

Re: [Pharo-project] Issue 4012 in pharo: Explore It crashes when selected using mouse

by pharo＠googlecode.com

Updates: Status: FixToInclude Labels: Milestone-1.3 Comment #1 on issue 4012 by marcus.d...(a)gmail.com: Explore It crashes when selected using mouse http://code.google.com/p/pharo/issues/detail?id=4012 fix attached (typo, the "self" there should not be there) Attachments: FixExploreIT.1.cs 290 bytes

April 14, 2011

Re: [Pharo-project] Issue 4010 in pharo: References to it nor working in Inspector

by pharo＠googlecode.com

Updates: Status: FixToInclude Comment #1 on issue 4010 by marcus.d...(a)gmail.com: References to it nor working in Inspector http://code.google.com/p/pharo/issues/detail?id=4010 fix attached Attachments: FixInspectorRefs.1.cs 224 bytes

April 14, 2011

Re: [Pharo-project] Issue 4008 in pharo: DNU on opening inspector with enabled taskbar

by pharo＠googlecode.com

Updates: Status: FixToInclude Comment #2 on issue 4008 by marcus.d...(a)gmail.com: DNU on opening inspector with enabled taskbar http://code.google.com/p/pharo/issues/detail?id=4008 fix attached Attachments: FixInspector.1.cs 1.1 KB

April 14, 2011

Re: [Pharo-project] isHealthy

by Igor Stasenko

On 14 April 2011 10:18, Henrik Sperre Johansen <henrik.s.johansen(a)veloxit.no> wrote: > On 14.04.2011 10:09, Igor Stasenko wrote: >> >> On 13 April 2011 16:49, StÃ©phane Ducasse<stephane.ducasse(a)inria.fr> >> Â wrote: >>> >>> Hi igor >>> >>> this is strange I have a dictionary whose array contains nil Â and still >>> isHealthy returns true. >>> can an array of a dictionary contains nil? >>> >> no, it can't . >> And how you end up with dictionary which having array = nil? During >> initialization, it allocates and initializes array, >> so, normally, there is no way how it could be nil. > > Ehm, the array can _contain_ nil(the empty slot marker) (and it will in all > cases, if it's working correctly), it cannot _be_ nil though. > > isHealthy has nothing to do with this though, it checks if all elements > (non-nil entries in the array) are at positions which are valid. >\ Err.. maybe i misunderstood? i meant dict array == nil should not happen, but (dict array at: someindex ) == nil is quite normal. > Cheers, > Henry -- Best regards, Igor Stasenko AKA sig.

April 14, 2011

[Pharo-project] Issue 4012 in pharo: Explore It crashes when selected using mouse

by pharo＠googlecode.com

Status: New Owner: ---- New issue 4012 by DougEdmu...(a)gmail.com: Explore It crashes when selected using mouse http://code.google.com/p/pharo/issues/detail?id=4012 Pharo image: Pharo | Pharo-core Pharo core version: Pharo1.3a Latest update: #13144 Virtual machine used: PHaro4.1.1 on Win32 Class browser used (if applicable): "SystemBrowser default" Steps to reproduce: 1. Open a workspace 2. Type UITheme builder (or just about anything) 3. Highlight line, right click, select 'Explore it' from context menu using mouse. Does not open an 'explorer' window "SmalltalkEditor(Object)>>doesNotUnderstand #self NOTE: If keyboard is used (Ctrl-SHIFT-I) instead of the mouse, then it DOES work. debug log attached Attachments: PharoDebug.log 35.9 KB

April 14, 2011

Re: [Pharo-project] About float: new chapter looking for reader and contributors

by StÃ©phane Ducasse

Nicolas why don't you grab the latex file and edit it? because I do not know anything about float. Stef On Apr 13, 2011, at 10:37 PM, Nicolas Cellier wrote: > Here is a small variation. It's not perfect, and most elements are > already in Stephane's text. > But maybe we can jump deeper in the first example that claims some explanations. > > We can first explain that 0.1 will answer the Float nearest to (1/10). > Thanks to this important property, if we enter 0.1, it will be printed > 0.1 and reinterpreted the same. A nice property to have! > > However, what is fundamental is that this Float won't be equal to (1/10). > How is this so ? Hey we didn't learn that in school ! > Well, Float have an internal representation in base 2, of the form > mantissa * (2 raisedTo: exponent). > There is no way to represent (1/10) in base 2 with a finite number of > bits... (like illustrated with 1.3 example, #significandAsInteger, > #exponent, #ulp and such kind of messages...). > A rounding operation has to occur to make this number fit in Float > internal representation ( it might be good to tell that Pharo Float > follow the IEEE 754 double precision standard with a link to > http://en.wikipedia.org/wiki/IEEE_754-1985 . This standard governs the > way most FPU work on this planet). > This rounding operation introduce a rounding error, and thus we don't > get exactly (1/10). > > To know the exact internal representation of 0.1 the Smalltalk way is > as usual to send a message: 0.1 asTrueFraction. > The same goes with 0.2, it's not equal to (2/10), check it with 0.2 > asTrueFraction. > > So what goes on with this operation 0.1+0.2 ? > In fact you asked the system to perform following operation (0.1 > asTrueFraction+0.2 asTrueFraction) asFloat. > (0.1 asTrueFraction+0.2 asTrueFraction) is an exact operation, but the > result again does not fit in Float internal representation: > (0.1 asTrueFraction+0.2 asTrueFraction) numerator highBit -> 54 > (0.1 asTrueFraction+0.2 asTrueFraction) numerator lowBit -> 1 > This means that 54 bits of mantissa are required to represent this > number. Float only have 53 > Float precision -> 53 > So converting it to aFloat requires another rounding operation, and > due to this rounding error, > (0.1 asTrueFraction+0.2 asTrueFraction) ~= (0.1 asTrueFraction+0.2 > asTrueFraction) asFloat. > That's exactly how your IEEE-754 compliant FPU will work. > > In the whole process, 3 rounding errors have been cumulated: > (1/10) asFloat -> 0.1 (the error is not yet visible, but it's here already) > (2/10) asFloat -> 0.2 (same) > (0.1 asTrueFraction+0.2 asTrueFraction) asFloat -> 0.30000000000000004 > > This is to be compared to 0.3, which has a single rounding error: > (3/10) asFloat -> 0.3 > > Due to these rounding errors, and the way they cumulate or annihilate, > both result might differ. And in this case, they differ. > This is a very important property of Float. Float are fast thanks to > hardware acceleration, and thanks to these rounding errors that keep > the number of significant bits from growing. But the counterpart is > that operations on Float are inexact. Due to this inexactness, it is > most often inadequate to rely on strict equality of Float, as this > very simple example illustrates. Instead, Float comparisons shall > better be tested with fuzzy tolerance. > > Note that the nice thing with Pharo is that you immediately see that > (0.1+0.2) ~= 0.3 thanks to extraneous digits printed. > Pharo does not hide the horrible truth by shortening the printed > representation to 0.3 like some system do. > However, the decimal printed form does not show you the truth about > 0.1 ~= (1/10). Inexactness is hidden. This is an implicit knowledge to > remember about Float, that you now learned with this lesson. > > Remember, this is not a deficiency of Pharo. This is the way Float are > expected to work whatever the language. > > Nicolas > > 2011/4/13 laurent laffont <laurent.laffont(a)gmail.com>: >> >> >> >> On Tue, Apr 12, 2011 at 6:07 PM, stephane ducasse <stephane.ducasse(a)free.fr> >> wrote: >>> >>> Hi guys >>> >>> I started to put in shape a chapter on floats based on the numerous >>> discussions we got over the years. >>> You can find it on github under the pharo by example book/Floats >> >> >> For me it's a good candidate for a ProfStef tutorial (text, evaluations, >> text, ...) >> Laurent >> >>> >>> Stef >>> >> >> >

April 14, 2011