OK. Here's my second stupid question for today.
What's the rational behind having 0, [] and "" evaluate to true? ""
and [], I could kind of see. But 0, how on Gods earth can 0 true?
alex
--
Alex Polite
http://flosspick.org - finding the right open source
I'm new to ruby but this makes sense to me. Why should 0 == false? It's a
valid FixNum.
On 1/28/06 3:51 PM, "Alex Polite" <notmyprivateemail@gmail.com> wrote:
OK. Here's my second stupid question for today.
What's the rational behind having 0, and "" evaluate to true? ""
and , I could kind of see. But 0, how on Gods earth can 0 true?alex
--
Alex Polite
http://flosspick.org - finding the right open source
Alex Polite wrote:
OK. Here's my second stupid question for today.
What's the rational behind having 0, and "" evaluate to true? ""
and , I could kind of see. But 0, how on Gods earth can 0 true?alex
--
Alex Polite
http://flosspick.org - finding the right open source
how on earth can -1 be true?
No special reason, it's just that way. use zero? if you want to know if it's zero. (What bugs you is the low level knowledge (or better an idea) on how 0 and false would be represented in memory - Qnil is a 4 in ruby :))
cheers
Simon
btw: i love pythons way in this case
0 *the integer* is only false by convention, and it's a convention confined to programming, originating (unless I'm mistaken) from languages which didn't define specific 'true' and 'false' logcial values separate from integer math. 0's used in some logical notations as a symbol for 'false', but it's unlikely that anyone familiar with formal logic will tell you those 0's are the same 0's you get from "2 - 2".
There's no doubt that the convention's been made very useful, but there's really no logical basis for equating any particular symbol to true or false truth values over any other.
matthew smillie.
On Jan 28, 2006, at 20:51, Alex Polite wrote:
OK. Here's my second stupid question for today.
What's the rational behind having 0, and "" evaluate to true? ""
and , I could kind of see. But 0, how on Gods earth can 0 true?
Well I do understand that it's a convention. They same is true for a
lot of things. Like the positioning of gas and break pedals in cars.
It's just a convention. But when GM puts a new car in the market they
don't swap them. My question is why the constructors of Ruby did?
alex
On 1/28/06, Matthew Smillie <M.B.Smillie@sms.ed.ac.uk> wrote:
On Jan 28, 2006, at 20:51, Alex Polite wrote:
> OK. Here's my second stupid question for today.
>
> What's the rational behind having 0, and "" evaluate to true? ""
> and , I could kind of see. But 0, how on Gods earth can 0 true?0 *the integer* is only false by convention,
--
Alex Polite
http://flosspick.org - finding the right open source
I think 0 is false because of the way it is represented in low-level
languages: a 0 (in binary). False is 0 too, and true is 1.
The Ruby definition of false/true is much simpler: everything except nil
or false is true.
Jules
--
Posted via http://www.ruby-forum.com/.
Among other things, it makes things like ||= much more useful.
-mental
On Sun, 2006-01-29 at 06:39 +0900, Alex Polite wrote:
Well I do understand that it's a convention. They same is true for a
lot of things. Like the positioning of gas and break pedals in cars.
It's just a convention. But when GM puts a new car in the market they
don't swap them. My question is why the constructors of Ruby did?
alex
Alex Polite wrote:
Well I do understand that it's a convention. They same is true for a
lot of things. Like the positioning of gas and break pedals in cars.
It's just a convention. But when GM puts a new car in the market they
don't swap them. My question is why the constructors of Ruby did?
Well... 0 evaluating to false is a convention used mainly in the C/C++
programming world. Many other languages that have been around for years
don't treat 0 as false. Pascal being one of them, IIRC. So Ruby is not
really breaking with a convention -- as there is none.
Sebastian
--
Drawing on my fine command of language, I said nothing.
0 *the integer* is only false by convention,
Well I do understand that it's a convention. They same is true for a
lot of things. Like the positioning of gas and break pedals in cars.
Computer languages are not cars, nor are all conventions equal. For example, I'm unaware of any convention on what material the seats should be covered in. As far as 0 goes, there are languages out there which don't even use numbers, let alone define particular integers as 'true' or 'false'.
There are any number of reasons to favour either approach over the other, so I couldn't possibly pick the exact reasons Ruby is the way that it is, but there are a couple reasons to not let 0 equate to false if you look at the very top of this page:
matthew smillie.
Alex Polite wrote:
Well I do understand that it's a convention. They same is true for a
lot of things. Like the positioning of gas and break pedals in cars.
It's just a convention. But when GM puts a new car in the market they
don't swap them. My question is why the constructors of Ruby did?
alex
When you get used to it, it's quite handy. Some methods return integers, and false values on failures. If 0 was false, you'd have to distinguish between 0 and false/nil when checking for success.
Regards,
Stefan
yeah. that makes sense.
alex
On 1/28/06, Stefan Walk <stefan.walk@gmail.com> wrote:
When you get used to it, it's quite handy. Some methods return integers,
and false values on failures. If 0 was false, you'd have to distinguish
between 0 and false/nil when checking for success.
--
Alex Polite
http://flosspick.org - finding the right open source
When you get used to it, it's quite handy. Some methods return integers,
and false values on failures. If 0 was false, you'd have to distinguish
between 0 and false/nil when checking for success.
One example of this that tripped me up today is the regular expression
match operator (=~), which returns (0-based) the index of a match, or
nil otherwise. If 0 was false, you couldn't do:
if str =~ /^Hello/
.....
Dynamic typing in Ruby also aids the use of false = false and 0 = 0.
In Java I can't suddenly say that my variable contains a 'False' value. I
would have to make my int = 0 and detect the rationale behind that specific
integer. Dynamic typing solves this because myVariable = 5 and later it can
equal 'false' when it really is false (rather than a
number that represents false)
-Clint
On 1/29/06, Alex Polite <notmyprivateemail@gmail.com> wrote:
On 1/28/06, Stefan Walk <stefan.walk@gmail.com> wrote:
> When you get used to it, it's quite handy. Some methods return integers,
> and false values on failures. If 0 was false, you'd have to distinguish
> between 0 and false/nil when checking for success.