Nicolas Cellier uploaded a new version of Kernel to project The Trunk: http://source.squeak.org/trunk/Kernel-nice.1054.mcz
==================== Summary ====================
Name: Kernel-nice.1054 Author: nice Time: 27 January 2017, 9:44:46.83377 pm UUID: ef21d74d-ba81-47c6-9bb7-92fb4140f494 Ancestors: Kernel-eem.1053
Change -0.0 sign to answer 0 instead of -1. Introduce a new message signBit for recognition of Float negativeZero.
Rationale: 1) The value of Float negativeZero cannot be distinguished from zero. Thus (Float negativeZero = 0.0) We can then expect sign to be symmetric for (positive) zero and negativeZero 2) ANSI Smalltalk requires above behavior. This will reduce un-necessary difference with Gemstone for example.
About NaN: Note that with old implementation, the sign of "positive" nan was 0, while it was -1 for "negative" nan. New implementation will allways answer 0 for nans.
We may as well answer Float nan, but currently sign will allways answer an Integer (-1,0 or 1). Until it is well specified by a standard, let's not bother. Otherwise, we could answer a Float if receiver is a Float like:
sign self > 0.0 ifTrue: [ ^1.0]. self < 0.0 ifTrue: [ ^-1.0]. ^self
=============== Diff against Kernel-eem.1053 ===============
Item was changed: ----- Method: Float>>arcTan: (in category 'mathematical functions') ----- arcTan: denominator + "Answer the angle in radians, taking care of 4 quadrants. + Implementation note: use signBit and sign: in order to catch cases of negativeZero" - "Answer the angle in radians. - Optional. See Object documentation whatIsAPrimitive. - Implementation note: use sign in order to catch cases of negativeZero"
+ self = 0.0 + ifTrue: + [denominator signBit = 0 ifTrue: [ ^0.0 ]. + ^Pi sign: self ]. + denominator = 0.0 ifTrue: [ ^Halfpi sign: self ]. + denominator > 0.0 ifTrue: [ ^(self / denominator) arcTan ]. + ^(self / denominator) arcTan + (Pi sign: self)! - self = 0.0 ifTrue: [ - denominator sign >= 0 ifTrue: [ ^0.0 ]. - self sign >= 0 ifTrue: [ ^Pi ]. - ^0.0 - Pi ]. - denominator = 0.0 ifTrue: [ - self > 0.0 ifTrue: [ ^Halfpi ]. - ^0.0 - Halfpi ]. - denominator > 0.0 ifTrue: [ ^(self / denominator) arcTan ]. - self > 0.0 ifTrue: [ ^(self / denominator) arcTan + Pi ]. - ^(self / denominator) arcTan - Pi!
Item was changed: ----- Method: Float>>byteEncode:base: (in category 'printing') ----- byteEncode: aStream base: base "Handle sign, zero, and NaNs; all other values passed to absPrintOn:base:"
self isNaN ifTrue: [aStream print: 'NaN'. ^ self]. "check for NaN before sign" self > 0.0 ifTrue: [self absByteEncode: aStream base: base] ifFalse: + [self signBit = 1 - [self sign = -1 ifTrue: [aStream print: '-']. self = 0.0 ifTrue: [aStream print: '0.0'. ^ self] ifFalse: [aStream writeNumber:self negated base: base]]!
Item was removed: - ----- Method: Float>>copySignTo: (in category 'mathematical functions') ----- - copySignTo: aNumber - "Return a number with same magnitude as aNumber and same sign as self. - Implementation note: take care of Float negativeZero, which is considered as having a negative sign." - - (self > 0.0 or: [(self at: 1) = 0]) ifTrue: [^ aNumber abs]. - ^aNumber withNegativeSign!
Item was changed: ----- Method: Float>>printOn:base: (in category 'printing') ----- printOn: aStream base: base "Print the receiver with the minimal number of digits that describes it unambiguously. This way, every two different Float will have a different printed representation. More over, every Float can be reconstructed from its printed representation with #readFrom:."
self isNaN ifTrue: [aStream nextPutAll: 'NaN'. ^ self]. "check for NaN before sign" self > 0.0 ifTrue: [self absPrintExactlyOn: aStream base: base] ifFalse: + [self signBit = 1 - [self sign = -1 ifTrue: [aStream nextPutAll: '-']. self = 0.0 ifTrue: [aStream nextPutAll: '0.0'] ifFalse: [self negated absPrintExactlyOn: aStream base: base]]!
Item was changed: ----- Method: Float>>printOn:maxDecimalPlaces: (in category 'printing') ----- printOn: aStream maxDecimalPlaces: placesDesired "Refine super implementation in order to avoid any rounding error caused by rounded or roundTo:" self isFinite ifFalse: [^self printOn: aStream]. self > 0.0 ifTrue: [self absPrintExactlyOn: aStream base: 10 decimalPlaces: placesDesired showTrailingFractionalZeros: false] ifFalse: + [self signBit = 1 - [self sign = -1 ifTrue: [aStream nextPutAll: '-']. self = 0.0 ifTrue: [aStream nextPutAll: '0.0'] ifFalse: [self absPrintExactlyOn: aStream base: 10 decimalPlaces: placesDesired showTrailingFractionalZeros: false]]!
Item was changed: ----- Method: Float>>printOn:showingDecimalPlaces: (in category 'printing') ----- printOn: aStream showingDecimalPlaces: placesDesired "Refine super implementation in order to avoid any rounding error caused by rounded or roundTo:" self isFinite ifFalse: [^self printOn: aStream]. self > 0.0 ifTrue: [self absPrintExactlyOn: aStream base: 10 decimalPlaces: placesDesired showTrailingFractionalZeros: true] ifFalse: + [self signBit = 1 - [self sign = -1 ifTrue: [aStream nextPutAll: '-']. self = 0.0 ifTrue: [aStream nextPut: $0. placesDesired > 0 ifTrue: [aStream nextPut: $.; next: placesDesired put: $0]] ifFalse: [self absPrintExactlyOn: aStream base: 10 decimalPlaces: placesDesired showTrailingFractionalZeros: true]]!
Item was removed: - ----- Method: Float>>sign (in category 'mathematical functions') ----- - sign - "Answer 1 if the receiver is greater than 0, -1 if less than 0, else 0. - Handle IEEE-754 negative-zero by reporting a sign of -1" - - self > 0.0 ifTrue: [ ^1 ]. - self < 0.0 ifTrue: [ ^-1 ]. - ^0 - ((self at: 1) bitShift: -31) "-1 for negative zero, 0 otherwise"!
Item was removed: - ----- Method: Float>>sign: (in category 'mathematical functions') ----- - sign: aNumber - "Return a Number with the same sign as aNumber and same magnitude as self. - Implementation is different from super to handle the special case of Float negativeZero." - - (self = 0.0 and: [aNumber sign negative]) ifTrue: [^Float negativeZero]. - ^aNumber copySignTo: self!
Item was added: + ----- Method: Float>>signBit (in category 'mathematical functions') ----- + signBit + "Answer 1 if the receiver has sign bit set (including case of IEEE-754 negative-zero). + Answer 0 otherwise" + + ^((self at: 1) bitShift: -31)!
Item was changed: ----- Method: Float>>storeOn:base: (in category 'printing') ----- storeOn: aStream base: base "Print the Number exactly so it can be interpreted back unchanged" self isFinite + ifTrue: [self signBit = 1 ifTrue: [aStream nextPutAll: '-']. - ifTrue: [self sign = -1 ifTrue: [aStream nextPutAll: '-']. base = 10 ifFalse: [aStream print: base; nextPut: $r]. self = 0.0 ifTrue: [aStream nextPutAll: '0.0'] ifFalse: [self abs absPrintExactlyOn: aStream base: base]] ifFalse: [self isNaN ifTrue: [aStream nextPutAll: 'Float nan'] ifFalse: [self > 0.0 ifTrue: [aStream nextPutAll: 'Float infinity'] ifFalse: [aStream nextPutAll: 'Float infinity negated']]]!
Item was removed: - ----- Method: Float>>withNegativeSign (in category 'converting') ----- - withNegativeSign - "Same as super, but handle the subtle case of Float negativeZero" - - self = 0.0 ifTrue: [^self class negativeZero]. - ^super withNegativeSign!
Item was added: + ----- Method: LargeNegativeInteger>>signBit (in category 'testing') ----- + signBit + "Optimization." + + ^1 + !
Item was added: + ----- Method: LargePositiveInteger>>signBit (in category 'testing') ----- + signBit + "Optimization." + + ^0!
Item was changed: ----- Method: Number>>copySignTo: (in category 'mathematical functions') ----- copySignTo: aNumber "Return a number with same magnitude as aNumber and same sign as self."
+ ^ self signBit = 0 - ^ self positive ifTrue: [aNumber abs] + ifFalse: [aNumber abs negated].! - ifFalse: [aNumber withNegativeSign].!
Item was added: + ----- Method: Number>>signBit (in category 'mathematical functions') ----- + signBit + "Answer 1 if the receiver is negative, zero otherwise." + + self < 0 ifTrue: [^1]. + ^0!
Item was removed: - ----- Method: Number>>withNegativeSign (in category 'converting') ----- - withNegativeSign - "Answer a number with same magnitude than receiver and negative sign." - ^self abs negated!