Ruby feature request - enum.detect_index

[jonT]

Hi,

I'd like to propose a new addition to the enum module.

detect works great but doesn't supply the index of the match. It would
be nice to have a method detect_index that returned the index rather
than the object.

Use example:

irb(main):001:0> foo =`uptime`.strip.split(' ')
=> ["14:36:06", "up", "157", "days,", "16:59,", "35", "users,", "load",
"average:", "0.54,", "0.31,", "0.27"]
irb(main):002:0> bar=nil
=> nil
irb(main):003:0> foo.each_with_index {|o,i| if o=="users,"; bar=i;
break; end;}
=> nil
irb(main):004:0> foo[2..bar-2]
=> ["157", "days,", "16:59,"]

Lines 2 to 4 would be expressed in a much more concise manner, i.e.

irb(main):001:0> foo =`uptime`.strip.split(' ')
=> ["14:36:06", "up", "157", "days,", "16:59,", "35", "users,", "load",
"average:", "0.54,", "0.31,", "0.27"]
irb(main):002:0> foo[2..foo.detect_index {|o| o=="users,"}-2]
=> ["157", "days,", "16:59,"]

Thoughts?

Jon T

 

[Levin Alexander]

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[Yukihiro Matsumoto]

Hi,

In message "Re: Ruby feature request - enum.detect_index"

|detect works great but doesn't supply the index of the match. It would
|be nice to have a method detect_index that returned the index rather
|than the object.

Nice idea. I'd rather name it 'find_index' though.

matz.

 

[Ross Bamford]

I'd like to propose a new addition to the enum module.

detect works great but doesn't supply the index of the match. It would
be nice to have a method detect_index that returned the index rather
than the object.

Use example:

irb(main):001:0> foo =`uptime`.strip.split(' ')
=> ["14:36:06", "up", "157", "days,", "16:59,", "35", "users,", "load",
"average:", "0.54,", "0.31,", "0.27"]
irb(main):002:0> bar=nil
=> nil
irb(main):003:0> foo.each_with_index {|o,i| if o=="users,"; bar=i;
break; end;}
=> nil
irb(main):004:0> foo[2..bar-2]
=> ["157", "days,", "16:59,"]

Lines 2 to 4 would be expressed in a much more concise manner, i.e.

irb(main):001:0> foo =`uptime`.strip.split(' ')
=> ["14:36:06", "up", "157", "days,", "16:59,", "35", "users,", "load",
"average:", "0.54,", "0.31,", "0.27"]
irb(main):002:0> foo[2..foo.detect_index {|o| o=="users,"}-2]
=> ["157", "days,", "16:59,"]

For this case, this might work?

foo[2..foo.index("users,")-2]
# => ["1", "day,", "14:18,"]

More generally, I'd personally like a block on 'index', such that:

foo.index("users,")
# => 6

foo.index { |s| s == "users," }
# => 6

Just MHO.

 

[Robert Klemme]

Hi,

In message "Re: Ruby feature request - enum.detect_index"


Nice idea. I'd rather name it 'find_index' though.

Don't we have that already?
=> 2

Or am I missing something?

Kind regards

robert

 

[Yukihiro Matsumoto]

Hi,

In message "Re: Ruby feature request - enum.detect_index"

|More generally, I'd personally like a block on 'index', such that:
|
| foo.index("users,")
| # => 6
|
| foo.index { |s| s == "users," }
| # => 6

It does so in 1.9.

matz.

 

[James Edward Gray II]

Don't we have that already?

=> 2

Or am I missing something?

You can not use a block of Ruby code to select the item you would
like an index for, in this example.

James Edward Gray II

 

[Ross Bamford]

Hi,

In message "Re: Ruby feature request - enum.detect_index"
on Mon, 6 Feb 2006 00:43:20 +0900, "Ross Bamford"

|More generally, I'd personally like a block on 'index', such that:
|
| foo.index("users,")
| # => 6
|
| foo.index { |s| s == "users," }
| # => 6

It does so in 1.9.

Cool, so it does I need to update my snapshot more often I guess ...

Thanks,

 

[Robert Klemme]

You can not use a block of Ruby code to select the item you would
like an index for, in this example.

Good point. In that case I'd just change the implementation of #index to
either accept an argument or a block. This cannot break old code because at
the moment blocks are not permitted / ignored.

Kind regards

robert

 

[jonT]

|More generally, I'd personally like a block on 'index', such that:

|
| foo.index("users,")
| # => 6
|
| foo.index { |s| s == "users," }
| # => 6

It does so in 1.9.

Ah! in that case my detect_index suggestion was rather unnecessary
[apologies - I also am guilty of running an ancient version of 1.9
(ubuntu's is ruby 1.9.0 (2005-06-23) (!)]

Jon T