Hi, Just thought it was weird that Ruby doesn''t automatically cast ints to floats. Seems so un-rubyish irb(main):006:0> 12/16 => 0 irb(main):007:0> 12.to_f / 16.to_f => 0.75 Jeroen
On 2006.04.02., at 10:16, Jeroen Houben wrote:> Just thought it was weird that Ruby doesn''t automatically cast ints > to floats. Seems so un-rubyishTry this one: irb(main):003:0> 12.0 / 16 => 0.75 irb(main):004:0> Place a dot and zero digit after integers to have a floating number. Here''s the same in Java: itigga: segabor$ more test.java class Test { public static void main(String[] args) { // first case System.out.println("12/16 = " + 12/16); // second case System.out.println("12.0/16 = " + 12.0/16); } } Running this the output will be: 12/16 = 0 12.0/16 = 0.75 If you write "12" language parser will mean it as integer. It is normal. Why should it mean as floating point number? I think it would be a major breakdown in memory footprint if Ruby converted all integers to floating point numbers. G?bor -------------- next part -------------- An HTML attachment was scrubbed... URL: http://wrath.rubyonrails.org/pipermail/rails/attachments/20060402/e50b8333/attachment.html
G?bor SEBESTY?N wrote:> > On 2006.04.02., at 10:16, Jeroen Houben wrote: > >> Just thought it was weird that Ruby doesn''t automatically cast ints to >> floats. Seems so un-rubyish >> > Try this one: > > irb(main):003:0> 12.0 / 16 > => 0.75 > irb(main):004:0> > > Place a dot and zero digit after integers to have a floating number. > Here''s the same in Java: > > itigga: segabor$ more test.java > class Test { > public static void main(String[] args) { > // first case > System.out.println("12/16 = " + 12/16); > // second case > System.out.println("12.0/16 = " + 12.0/16); > } > } > > Running this the output will be: > > 12/16 = 0 > 12.0/16 = 0.75 > > If you write "12" language parser will mean it as integer. It is normal. > Why should it mean as floating point number? > I think it would be a major breakdown in memory footprint if Ruby > converted all integers to floating point numbers.I''m not saying it should treat 12 as a float (I''m not saying it should do anything really) but I wonder if it would be a bad thing to automatically cast the outcome of a division if needed (like in PHP). <?php $a = 12; $b = 16; echo gettype($a) . "\n"; echo gettype($b) . "\n"; echo gettype($a/$b) . "\n"; echo gettype(6/3) . "\n"; ?> Vigor10:/tmp jeroen$ php test.php integer integer double integer Jeroen
There exists intuition to support that, although few commonly used programming languages take this route. Exceptions seem to be PHP and Python (soon) which admittedly are closer to ruby than C/C++. I don''t like the idea of winding up with an IEEE float as a result of an integer operation, being that integers and IEEE floats don''t exactly behave in the same way. I also don''t think that it''s a good idea for an operator to change its output type from a precise one to an imprecise one based on user input. Imprecise and precise numbers are fundamentally different and should probably not be mixed this freely. Maybe the real answer is to add precise math (rationals, decimals) to ruby, like lisp has. Then you''d end up knowing whether your math was ''precise'' at all times without exhibiting this mildly unintuitive behavior. You''d of course need a div operator for this to work. On 4/2/06, Jeroen Houben <jeroen@terena.nl> wrote:> G?bor SEBESTY?N wrote: > > > > On 2006.04.02., at 10:16, Jeroen Houben wrote: > > > >> Just thought it was weird that Ruby doesn''t automatically cast ints to > >> floats. Seems so un-rubyish > >> > > Try this one: > > > > irb(main):003:0> 12.0 / 16 > > => 0.75 > > irb(main):004:0> > > > > Place a dot and zero digit after integers to have a floating number. > > Here''s the same in Java: > > > > itigga: segabor$ more test.java > > class Test { > > public static void main(String[] args) { > > // first case > > System.out.println("12/16 = " + 12/16); > > // second case > > System.out.println("12.0/16 = " + 12.0/16); > > } > > } > > > > Running this the output will be: > > > > 12/16 = 0 > > 12.0/16 = 0.75 > > > > If you write "12" language parser will mean it as integer. It is normal. > > Why should it mean as floating point number? > > I think it would be a major breakdown in memory footprint if Ruby > > converted all integers to floating point numbers. > > I''m not saying it should treat 12 as a float (I''m not saying it should > do anything really) but I wonder if it would be a bad thing to > automatically cast the outcome of a division if needed (like in PHP). > > <?php > $a = 12; > $b = 16; > echo gettype($a) . "\n"; > echo gettype($b) . "\n"; > echo gettype($a/$b) . "\n"; > echo gettype(6/3) . "\n"; > ?> > > Vigor10:/tmp jeroen$ php test.php > integer > integer > double > integer > > Jeroen > _______________________________________________ > Rails mailing list > Rails@lists.rubyonrails.org > http://lists.rubyonrails.org/mailman/listinfo/rails >
On Sun, Apr 02, 2006 at 10:41:36AM +0200, Jeroen Houben wrote:> G?bor SEBESTY?N wrote: > > > >On 2006.04.02., at 10:16, Jeroen Houben wrote: > > > >>Just thought it was weird that Ruby doesn''t automatically cast ints to > >>floats. Seems so un-rubyish > >> > >Try this one: > > > >irb(main):003:0> 12.0 / 16 > >=> 0.75 > >irb(main):004:0> > > I''m not saying it should treat 12 as a float (I''m not saying it should > do anything really) but I wonder if it would be a bad thing to > automatically cast the outcome of a division if needed (like in PHP).So you perform the integer division 12 / 16, get a result of 0, and then cast that to a float 0.0? Not exactly useful. What you really need to do is perform a modulus operation and then do an integer division if the result of that is 0 and a floating point cast/division otherwise. Quite expensive. Also, if you really, really need integer division, then the PHP way leaves you out in the cold -- AFAIK, there''s no ''integer division'' operator in PHP, whereas, presumably, you can call .to_f on at least one of your arguments in Ruby if you want a floating point result. - Matt
Jeroen Houben wrote:> G?bor SEBESTY?N wrote: >> >> On 2006.04.02., at 10:16, Jeroen Houben wrote: >> >>> Just thought it was weird that Ruby doesn''t automatically cast ints >>> to floats. Seems so un-rubyishNo, this is exactly why Ruby is a strong dynamically typed language. Doing autoconversion is a very bad thing as unintentioned things can happen. If I tell the computer to dived two integers, I get an integer back. If I tell the computer to contatinate two strings I get a string back. If I tell the computer to add a string to a number Ruby should tell me "I can''t do it". That''s the whole point abouot strongly typed languages! Jonathan -- Jonathan Weiss http://blog.innerewut.de
Jonathan Weiss wrote:> Jeroen Houben wrote: >> G?bor SEBESTY?N wrote: >>> >>> On 2006.04.02., at 10:16, Jeroen Houben wrote: >>> >>>> Just thought it was weird that Ruby doesn''t automatically cast ints >>>> to floats. Seems so un-rubyish > > No, this is exactly why Ruby is a strong dynamically typed language. > Doing autoconversion is a very bad thing as unintentioned things can > happen. > > If I tell the computer to dived two integers, I get an integer back. If > I tell the computer to contatinate two strings I get a string back. If I > tell the computer to add a string to a number Ruby should tell me "I > can''t do it". > > That''s the whole point abouot strongly typed languages!That''s the kind of answer I was looking for. So I can definitely see why strongly typed languages are safe and predictable and all, but why (just out of interest) does PHP (and in the future phython?) have it? Jeroen
Matthew Palmer wrote:> On Sun, Apr 02, 2006 at 10:41:36AM +0200, Jeroen Houben wrote: >> G?bor SEBESTY?N wrote: >>> On 2006.04.02., at 10:16, Jeroen Houben wrote: >>> >>>> Just thought it was weird that Ruby doesn''t automatically cast ints to >>>> floats. Seems so un-rubyish >>>> >>> Try this one: >>> >>> irb(main):003:0> 12.0 / 16 >>> => 0.75 >>> irb(main):004:0> >> I''m not saying it should treat 12 as a float (I''m not saying it should >> do anything really) but I wonder if it would be a bad thing to >> automatically cast the outcome of a division if needed (like in PHP). > > So you perform the integer division 12 / 16, get a result of 0, and then > cast that to a float 0.0? Not exactly useful. What you really need to do > is perform a modulus operation and then do an integer division if the result > of that is 0 and a floating point cast/division otherwise. Quite expensive. >No I just wanted a float as the result of a division between two integers. I know how to do that (call .to_f on one of the integers). I was just wondering why Ruby behaves the way it does. J
> > That''s the kind of answer I was looking for. So I can definitely see why > strongly typed languages are safe and predictable and all, but why > (just out of interest) does PHP (and in the future phython?) have it?I can''t comment about Python but PHP is like Perl weakly typed. So in PHP/Perl 5 + "6" results in 11 While in Ruby (or e.g. Java) you have to say 5 + "6".to_i results in 11 Weakly typed languages do so because this behavious is somethimes handy as you save some characters as you do not have to explicitly convert types. The problem is that this can become dangerous when you didn''t want the autoconversion but forgot to explicitly tell the interpreter. Especially if one part of the input comes from the user. Say hello to many kinds of user injected code like SQLinjection or other malicious behaviour. E.g. what is 5 + "6a" ?? Depending on the language it could be 11 "56a" Or an exception. Now if it is the string "56a" and you really need a number further down in your code? Jonathan -- Jonathan Weiss http://blog.innerewut.de
On 4/2/06, Jeroen Houben <jeroen@terena.nl> wrote:> Matthew Palmer wrote: > > On Sun, Apr 02, 2006 at 10:41:36AM +0200, Jeroen Houben wrote: > >> G?bor SEBESTY?N wrote: > >>> On 2006.04.02., at 10:16, Jeroen Houben wrote: > >>> > >>>> Just thought it was weird that Ruby doesn''t automatically cast ints to > >>>> floats. Seems so un-rubyish > >>>> > >>> Try this one: > >>> > >>> irb(main):003:0> 12.0 / 16 > >>> => 0.75 > >>> irb(main):004:0> > >> I''m not saying it should treat 12 as a float (I''m not saying it should > >> do anything really) but I wonder if it would be a bad thing to > >> automatically cast the outcome of a division if needed (like in PHP). > > > > So you perform the integer division 12 / 16, get a result of 0, and then > > cast that to a float 0.0? Not exactly useful. What you really need to do > > is perform a modulus operation and then do an integer division if the result > > of that is 0 and a floating point cast/division otherwise. Quite expensive. > > > > No I just wanted a float as the result of a division between two > integers. I know how to do that (call .to_f on one of the integers). I > was just wondering why Ruby behaves the way it does. > > J > _______________________________________________ > Rails mailing list > Rails@lists.rubyonrails.org > http://lists.rubyonrails.org/mailman/listinfo/rails >Well it would not make me happy, but I am all about choice :-) class Fixnum def /(int) self.to_f / int end end p 12 / 16 pth
irb(main):001:0> 12.quo(16)
=> 0.75
Erik.
Jeroen Houben schreef:> Hi,
>
> Just thought it was weird that Ruby doesn''t automatically cast
ints to
> floats. Seems so un-rubyish
>
> irb(main):006:0> 12/16
> => 0
> irb(main):007:0> 12.to_f / 16.to_f
> => 0.75
>
> Jeroen
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
On 3-apr-2006, at 9:26, Erik van Oosten wrote:> irb(main):001:0> 12.quo(16) > => 0.75Wow!
Le Lundi 03 Avril 2006 14:25, Julian ''Julik'' Tarkhanov a ?crit?:> On 3-apr-2006, at 9:26, Erik van Oosten wrote: > > irb(main):001:0> 12.quo(16) > > => 0.75There''s also 12.0 / 16.0. You muste tell ruby that you''re using float not integer. Bye. -- Nicolas Cavigneaux | GPG keyID : CFE76D24 nico@bounga.org | http://www.bounga.org -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 191 bytes Desc: not available Url : http://wrath.rubyonrails.org/pipermail/rails/attachments/20060403/d54c2f91/attachment.bin
Julian ''Julik'' Tarkhanov wrote:> On 3-apr-2006, at 9:26, Erik van Oosten wrote: > >> irb(main):001:0> 12.quo(16) >> => 0.75 > > Wow!I anxiously await the day when I can see an example like that and say "I knew that". Of course, given my memory these days, maybe I *had* seen that... :-) Keith -- Posted via http://www.ruby-forum.com/.
Jonathan Weiss wrote:> No, this is exactly why Ruby is a strong dynamically typed language. > Doing autoconversion is a very bad thing as unintentioned things can > happen. > > If I tell the computer to dived two integers, I get an integer back. > > That''s the whole point abouot strongly typed languages!irb(main):002:0> 10000000.class => Fixnum irb(main):003:0> 10000000.class => Fixnum irb(main):004:0> (10000000 * 1000000).class => Bignum Except where Ruby does autoconversion to make your life easier. For the record, I don''t think Ruby should do the int->float conversion, but it''s for reasons of precision, not type purity. What does Smalltalk do in similar circumstances ? (not a leading question, I genuinely don''t know :) Alan -- Posted via http://www.ruby-forum.com/.
2006/4/3, Alan Francis <alancfrancis@gmail.com>:> What does Smalltalk do in similar circumstances ? (not a leading > question, I genuinely don''t know :)The version of Squeak I tested has real Fraction objects. Which means 12/16 gets converted to a 3/4 Fraction. Bye ! -- Fran?ois Beausoleil http://blog.teksol.info/
irb(main):001:0> require ''mathn''
=> true
irb(main):002:0> 12 / 16
=> 3/4
;)
Erik.
Francois Beausoleil schreef:> 2006/4/3, Alan Francis <alancfrancis@gmail.com>:
>
>> What does Smalltalk do in similar circumstances ? (not a leading
>> question, I genuinely don''t know :)
>>
>
> The version of Squeak I tested has real Fraction objects. Which means
> 12/16 gets converted to a 3/4 Fraction.
>
> Bye !
>