This is quite embarassing because I Don’t consider myself a poor
programmer, but I just started looking at ruby the other day.
Blocks seem to be a good way to iterate through something to search for
an entry for instance. It’s easy to return the object that meets
certain criteria using blocks but I’m finding it hard to return the
index of that particular object in, say, an array.
as an example
arr=[4,1,3,7]
arr.find { |f| f==someval }
will return the val within arr that matches someval, which doesn’t
really help me because I already have someval
How do I actually return the index in arr to the first match of someval.
so if someval == 3, my block would return 2, for the above example
–
Daniel B. http://danielbaird.com (TiddlyW;nks! :: Whiteboard Koala :: Blog ::
Things
That Suck)
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On Wed, 2006-03-15 at 13:08 +0900, Tod McIntyre wrote:
This is quite embarassing because I Don’t consider myself a poor
programmer, but I just started looking at ruby the other day.
Blocks seem to be a good way to iterate through something to search for
an entry for instance. It’s easy to return the object that meets
certain criteria using blocks but I’m finding it hard to return the
index of that particular object in, say, an array.
arr=[4,1,3,7]
arr.find { |f| f==someval }
will return the val within arr that matches someval, which doesn’t
really help me because I already have someval
Yeah, but this is just a special case. With a block you can employ
arbitrary selection criteria - not just ==.
How do I actually return the index in arr to the first match of someval.
so if someval == 3, my block would return 2, for the above example
As Ross and Daniel have pointed out already, use #index.
Kind regards
robert
Once again I knew this would be a simple answer!! I thank you for your
quick responses. Obviously I should be reading the api more thoroughly
before posting.
Once again I knew this would be a simple answer!! I thank you for your
quick responses. Obviously I should be reading the api more thoroughly
before posting.
Ah, don’t bother. The API of the standard lib has it’s humps and bumps
(for example not fully consistent usage of ! for destructive methods
etc.)
so it’s normal to fall into one or the other pit initially.
arr=[4,1,3,7]
arr.find { |f| f==someval }
will return the val within arr that matches someval, which doesn’t
really help me because I already have someval
Yeah, but this is just a special case. With a block you can employ
arbitrary selection criteria - not just ==.
How do I actually return the index in arr to the first match of someval.
so if someval == 3, my block would return 2, for the above example
As Ross and Daniel have pointed out already, use #index.
Ah, don’t bother. The API of the standard lib has it’s humps and bumps (for
example not fully consistent usage of ! for destructive methods etc.) so it’s
normal to fall into one or the other pit initially.
I have to leap to the defense of ! It really is consistent:
given meth and meth!, meth! is the more “dangerous” version
“dangerous” often means “receiver-changing”, but definitely
does not have to mean that
methods whose names already imply receiver-changing don’t
have a ! because they don’t need one, and also ! methods
only come in pairs with a non-! equivalent. (It would be
hard to imagine what “Replace the contents of this string
object, but without changing the object” would mean…)
“Implying receiver-changing” is of course in the eyes of Matz But
while there are judgements, I don’t think there’s any inconsistency.
given meth and meth!, meth! is the more “dangerous” version
“dangerous” often means “receiver-changing”, but definitely
does not have to mean that
Although it’s certainly the most common use of “!”.
methods whose names already imply receiver-changing don’t
have a ! because they don’t need one, and also ! methods
only come in pairs with a non-! equivalent. (It would be
hard to imagine what “Replace the contents of this string
object, but without changing the object” would mean…)
“Implying receiver-changing” is of course in the eyes of Matz But
while there are judgements, I don’t think there’s any inconsistency.
Um, yes. I should print this out and place it in front of my monitor.
Somehow I keep forgetting this definition - must be some old newsgroup
thread having anchored deep in my subconscious.
Thanks for putting that straight!
Kind regards
robert
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