Enumerable#inject is surprising me...<Pine.LNX.4.44.0310090713420.21222-100000@ool-4355dfae.dyn.optonline.net>

[dblack@superlink.net]

Hi --

On Thu, 9 Oct 2003, ts wrote:

> >>>>> "d" == dblack <dblack@superlink.net> writes:

>
> d> $ ./ruby -e 'p ["a"].inject("start") {|x,y| break "b"}'
> d> "start"
>
> d> I'm still not understanding why these should be different, or how
> d> "start" gets into the first one (the first block) at all.
>
> svg% ruby -e 'p ["x", "y"].inject("a") {|x,y| break 12 if y == "y"; x + y}'
> "ax"
> svg%
>
> #inject ignore the value returned by break, and return the last result.

I thought "break val" executed a break *and* generated a return value
for the block at the same time:

irb(main):011:0> a = proc { break 3 } .call; a
=> 3

Why wouldn't #inject treat the break the same way?


David

--
David Alan Black
home: [email]dblack@superlink.net[/email]
work: [email]blackdav@shu.edu[/email]
Web: [url]http://pirate.shu.edu/~blackdav[/url]

[Christoph]

dblack wrote:
....

> > svg% ruby -e 'p ["x", "y"].inject("a") {|x,y| break 12 if y == "y"; x +

y}'

> > "ax"
> > svg%
> >
> > #inject ignore the value returned by break, and return the last result.

>
> I thought "break val" executed a break *and* generated a return value
> for the block at the same time:
>
> irb(main):011:0> a = proc { break 3 } .call; a
> => 3
>
> Why wouldn't #inject treat the break the same way?

Hi,

david assuming that the ``yield break thing'' would not
be in a broken state (relative to my own POLS that is)
you could implement inject along the lines

module Enumerable
def inject(start = nil)
if start
each {|e| start = yield start,e }
else
first = true
each {|e|
unless first
start = yield start,e
else
start = e
first = false
end
}
end
return start
end
end


in other words even if the inject iteration is is governornated
- ups terminated - unexpectedly at the end you would still
return the current ``start'' value.


/Christoph