collect! and Enumerable

[Jim Freeze]

Hi

I just noticed that Enumerable does not support collect! although
it does support collect. Was this changed from earlier versions?
If so, why?

irb(main):001:0> class M
irb(main):002:1> def each
irb(main):003:2> yield 1
irb(main):004:2> yield 2
irb(main):005:2> end
irb(main):006:1> end
=> nil
irb(main):007:0> class M
irb(main):008:1> include Enumerable
irb(main):009:1> end
=> M
irb(main):010:0> m=M.new
=> #<M:0x1892d0>
irb(main):011:0> m.collect { |i| i*2 }
=> [2, 4]
irb(main):012:0> m.collect! { |i| i*2 }
NoMethodError: undefined method `collect!' for #<M:0x1892d0>
from (irb):12

Thanks

 

[Mauricio Fernández]

Hi

I just noticed that Enumerable does not support collect! although
it does support collect. Was this changed from earlier versions?
If so, why?

irb(main):001:0> class M
irb(main):002:1> def each
irb(main):003:2> yield 1
irb(main):004:2> yield 2
irb(main):005:2> end
irb(main):006:1> end
=> nil
irb(main):007:0> class M
irb(main):008:1> include Enumerable
irb(main):009:1> end
=> M
irb(main):010:0> m=M.new
=> #<M:0x1892d0>
irb(main):011:0> m.collect { |i| i*2 }
=> [2, 4]
irb(main):012:0> m.collect! { |i| i*2 }
NoMethodError: undefined method `collect!' for #<M:0x1892d0>
from (irb):12

Does collect! (or map!) make sense for Enumerables? Keep in mind that
collect! (aka map!) is defined in Array.
I guess you could define it as
module Enumerable
def collect!(&b)
to_a.collect!(&b)
end
end
but I don't feel too bad about having to do to_a explicitly.

--
_ _
| |__ __ _| |_ ___ _ __ ___ __ _ _ __
| '_ \ / _` | __/ __| '_ ` _ \ / _` | '_ \
| |_) | (_| | |_\__ \ | | | | | (_| | | | |
|_.__/ \__,_|\__|___/_| |_| |_|\__,_|_| |_|
Running Debian GNU/Linux Sid (unstable)
batsman dot geo at yahoo dot com

There are 3 kinds of people: those who can count & those who can't.
-- Unknown source

 

[Robert Klemme]

Hi

I just noticed that Enumerable does not support collect! although
it does support collect. Was this changed from earlier versions?
If so, why?

irb(main):001:0> class M
irb(main):002:1> def each
irb(main):003:2> yield 1
irb(main):004:2> yield 2
irb(main):005:2> end
irb(main):006:1> end
=> nil
irb(main):007:0> class M
irb(main):008:1> include Enumerable
irb(main):009:1> end
=> M
irb(main):010:0> m=M.new
=> #<M:0x1892d0>
irb(main):011:0> m.collect { |i| i*2 }
=> [2, 4]
irb(main):012:0> m.collect! { |i| i*2 }
NoMethodError: undefined method `collect!' for #<M:0x1892d0>
from (irb):12

Does collect! (or map!) make sense for Enumerables? Keep in mind that
collect! (aka map!) is defined in Array.
I guess you could define it as
module Enumerable
def collect!(&b)
to_a.collect!(&b)
end
end
but I don't feel too bad about having to do to_a explicitly.

Especially since your definition of collect! would defy users'
expectations that it would do it in place while it really creates a copy.


Regards

robert

 

[Mauricio Fernández]

Especially since your definition of collect! would defy users'
expectations that it would do it in place while it really creates a copy.

that's why "Does collect! (or map!) make sense for Enumerables?",
but you expressed it so much better ;-)

--
_ _
| |__ __ _| |_ ___ _ __ ___ __ _ _ __
| '_ \ / _` | __/ __| '_ ` _ \ / _` | '_ \
| |_) | (_| | |_\__ \ | | | | | (_| | | | |
|_.__/ \__,_|\__|___/_| |_| |_|\__,_|_| |_|
Running Debian GNU/Linux Sid (unstable)
batsman dot geo at yahoo dot com

And Bruce is effectively building BruceIX
-- Alan Cox

 

[Robert Klemme]

that's why "Does collect! (or map!) make sense for Enumerables?",
but you expressed it so much better ;-)

Err, no. Apparently you wanted to say the same as I did but I was tricked
into believing something else by "I guess you could define it as ...".
Sounded like a positive suggestion to me. Now, who said English was easy?


Kind regards

robert

 

[Gavin Sinclair]

Hi

I just noticed that Enumerable does not support collect! although
it does support collect. Was this changed from earlier versions?
If so, why?

A. collect always returns an array.

B. Bang methods should not change the class of the receiver.