[Newbies] Re: Adding methods to Integers...
On Fri, 13 Apr 2007 13:39:08 +0200, Bert Freudenberg wrote: On Apr 13, 2007, at 13:27 , Klaus D. Witzel wrote: Hi Bert, on Thu, 12 Apr 2007 18:31:55 +0200, you wrote: This is actually wrong. :) Only SmallIntegers are special [*]. What happens is this: When you add two SmallIntegers (like 3 + 4), and the result is a SmallInteger, the result is calculated in the bytecode directly. Otherwise, a regular send of #+ is performed. Right. From there, everything else happens in the image, Not really. (Integer#+ aNumber) sends (self digitAdd: aNumber) which is implemented as primitive: 'primDigitAdd' module: 'LargeIntegers' which is part of the VM. Of course the LargeIntegers module may be absent, have failed to load, may not like the argument, etc. No, this is an *optional* primitive. It's there purely to speed up computation and can be safely removed. Sure, but this thread is not about what happens when the optional primitive is removed, and I was not reflecting that, either. I was rather discussing the point when the primitive does *not* fail on one of Patrick's subclasses and, what the returned species is. You could change the Integer classes to handle subclasses properly (via species etc.). So far, this has not been necessary. My point was that this (unlike SmallIntegers) is *not* hard-coded in the VM. I think it depends on operand order. When the LargeIntegers module is invoked (in my previous example when sending + myLargeInteger to SmallInteger 1) then a hard-coded instance of LargePositiveIntegers is returned. The attached class can be used (together with my previous example) to illustrate my point. The class does not inherit from some default large integer class and the primitive does not fail, regardless of operand order. I hope I didn't base my argument on a bug or mistake. FWIW I do not disagree with anything about your argument, except a bit with hard-coded. - Bert - MyPositiveInteger.st Description: Binary data ___ Beginners mailing list [EMAIL PROTECTED] http://lists.squeakfoundation.org/mailman/listinfo/beginners
Re: [Newbies] Re: Adding methods to Integers...
On Apr 13, 2007, at 14:35 , Klaus D. Witzel wrote: On Fri, 13 Apr 2007 13:39:08 +0200, Bert Freudenberg wrote: On Apr 13, 2007, at 13:27 , Klaus D. Witzel wrote: Hi Bert, on Thu, 12 Apr 2007 18:31:55 +0200, you wrote: This is actually wrong. :) Only SmallIntegers are special [*]. What happens is this: When you add two SmallIntegers (like 3 + 4), and the result is a SmallInteger, the result is calculated in the bytecode directly. Otherwise, a regular send of #+ is performed. Right. From there, everything else happens in the image, Not really. (Integer#+ aNumber) sends (self digitAdd: aNumber) which is implemented as primitive: 'primDigitAdd' module: 'LargeIntegers' which is part of the VM. Of course the LargeIntegers module may be absent, have failed to load, may not like the argument, etc. No, this is an *optional* primitive. It's there purely to speed up computation and can be safely removed. Sure, but this thread is not about what happens when the optional primitive is removed, and I was not reflecting that, either. I was rather discussing the point when the primitive does *not* fail on one of Patrick's subclasses and, what the returned species is. You could change the Integer classes to handle subclasses properly (via species etc.). So far, this has not been necessary. My point was that this (unlike SmallIntegers) is *not* hard-coded in the VM. I think it depends on operand order. When the LargeIntegers module is invoked (in my previous example when sending + myLargeInteger to SmallInteger 1) then a hard-coded instance of LargePositiveIntegers is returned. The attached class can be used (together with my previous example) to illustrate my point. The class does not inherit from some default large integer class and the primitive does not fail, regardless of operand order. I hope I didn't base my argument on a bug or mistake. I don't see your point. Do you want the primitive to fail for your class? This is outside of its spec, so to say. Do not use the primitive if you are not satisfied with its behavior. FWIW I do not disagree with anything about your argument, except a bit with hard-coded. It is not hard-coded in the VM, exactly as I wrote above. SmallInteger arithmetic is hard-coded: There is no way to generally redefine SmallInteger+ unless you modify the bytecode interpreter, because method is never actually activated unless you use #perform:, or the result is not a SmallInteger. But you are free to redefine what happens outside the realm of SmallIntegers. Invokation of the LargeInteger primitives is voluntary, you are not forced to use them. - Bert - ___ Beginners mailing list [EMAIL PROTECTED] http://lists.squeakfoundation.org/mailman/listinfo/beginners
[Newbies] Re: Adding methods to Integers...
Hi Patrick, some of the symptoms you describe have to do with a small set of classes being hardwired in Squeak's virtual machine. To see which they are, evaluate (printIt) Smalltalk specialObjectsArray select: [:each | each isBehavior] So when you do primitive arithmethic with your own subclass of LargePositiveInteger, the VM returns an instance of LargePositiveInteger (and not your subinstance of it). Of course the specialObjectsArray can be changed and from then on the VM (after being notified) will use your subclass but, I think this is not what you really want ;-) Putting your methods into Integer is fine as long as they do not conflict with anything else. Yes, this is the usual approach for adding new behavior to all the integers :) /Klaus On Thu, 12 Apr 2007 17:28:01 +0200, you wrote: Background: :: The most recent MathFactor Podcast ( http://mathfactor.uark.edu/ ) ended with a request to write a computer program that could, in principal, given enough time and memory, compute Graham's Number ( http://mathworld.wolfram.com/GrahamsNumber.html ). Smalltalk was a natural choice since it already supports LargeIntegers. Problem: ::: Being new to Smalltalk, my first thought was that I should make my own class as a subclass of LargePositiveInteger, put my methods there, and violá. Alas, no love. I ran into the following problems: * I couldn't find a way to give a value to myself. * I couldn't find a way to get integers to adapt to my class anyway. I ended up just adding my methods to the Integer class. But, this felt very naughty. Is it the usual approach? Thanks, Patrick ___ Beginners mailing list [EMAIL PROTECTED] http://lists.squeakfoundation.org/mailman/listinfo/beginners
Re: [Newbies] Re: Adding methods to Integers...
This is actually wrong. Only SmallIntegers are special [*]. What happens is this: When you add two SmallIntegers (like 3 + 4), and the result is a SmallInteger, the result is calculated in the bytecode directly. Otherwise, a regular send of #+ is performed. From there, everything else happens in the image, including conversion to LargeIntegers - see implementors of #+. Like, if the receiver was a SmallInteger, it tries the add primitive, which fails, and then the implementation of #+ in class Integer is invoked. This method then creates a large integer. For the implementation of all this see #bytecodePrimAdd and #primitiveAdd. You may have to load VMMaker first. - Bert - [*] Well, Floats are optimized a bit, and we have a plugin to speed up LargeIntegers, but this is all optional and doesn't matter in this discussion. On Apr 12, 2007, at 18:05 , Klaus D. Witzel wrote: Hi Patrick, some of the symptoms you describe have to do with a small set of classes being hardwired in Squeak's virtual machine. To see which they are, evaluate (printIt) Smalltalk specialObjectsArray select: [:each | each isBehavior] So when you do primitive arithmethic with your own subclass of LargePositiveInteger, the VM returns an instance of LargePositiveInteger (and not your subinstance of it). Of course the specialObjectsArray can be changed and from then on the VM (after being notified) will use your subclass but, I think this is not what you really want ;-) Putting your methods into Integer is fine as long as they do not conflict with anything else. Yes, this is the usual approach for adding new behavior to all the integers :) /Klaus On Thu, 12 Apr 2007 17:28:01 +0200, you wrote: Background: :: The most recent MathFactor Podcast ( http://mathfactor.uark.edu/ ) ended with a request to write a computer program that could, in principal, given enough time and memory, compute Graham's Number ( http://mathworld.wolfram.com/GrahamsNumber.html ). Smalltalk was a natural choice since it already supports LargeIntegers. Problem: ::: Being new to Smalltalk, my first thought was that I should make my own class as a subclass of LargePositiveInteger, put my methods there, and violá. Alas, no love. I ran into the following problems: * I couldn't find a way to give a value to myself. * I couldn't find a way to get integers to adapt to my class anyway. I ended up just adding my methods to the Integer class. But, this felt very naughty. Is it the usual approach? Thanks, Patrick ___ Beginners mailing list [EMAIL PROTECTED] http://lists.squeakfoundation.org/mailman/listinfo/beginners ___ Beginners mailing list [EMAIL PROTECTED] http://lists.squeakfoundation.org/mailman/listinfo/beginners
