for - next loop

rubyonrails-talk
1

Even my pickaxe book suggests this should work but it doesn't...

for tax in @taxes   next if ! (tax.taxauthid === [ 24, 25, 26, 27, 36, 37, 38, 39])   print tax.taxamount + " - " + tax.taxauthid + "\n" end

and my thinking is that if the tax.taxauthid is not found in the set of values, it should jump to the next value of tax.

Why doesn't this work?

Craig

2

Have you tried replacing the 'next' with another print statement to see whether it is the logic or the test that is failing? Do I see a space after the ! ? I have not tried it but Ruby can sometimes be a bit funny with spaces.

Colin

3

Hello Craig,

Why don't you use the include? method of Array instead, and get rid of the negation by using unless. It will make the code easier to read:

next unless [ 24, 25, 26, 27, 36, 37, 38, 39].include?(tax.taxauthid)

Franz

4

I am not familiar with 'triple equals' what is the difference between === and ==

If I were doing the same thing I'd write it

@taxes.each do |tax|

for tax in @taxes   next if ! (tax.taxauthid === [ 24, 25, 26, 27, 36, 37, 38, 39])   print tax.taxamount + " - " + tax.taxauthid + "\n" end

5

I may be posting this twice, sorry if thats the case...

Question, what is the difference between === and ==

If I were writing this I would write it with the member? method of array and avoid the next statement and the negation to make it as readable as possible.

@taxes.each do |tax|   if [24, 25, 26, 27, 36, 37, 38, 39].member? tax.taxauthid     print "#{tax.taxamount}-#{tax.taxauthid}\n"   end end

6

difficult to provide anything more ugly

7

If I understand correctly, you'd like to output some information about a selected group of taxes.

How about something like:

selected = @taxes.select { |tax| [24, 25, 26, 27, 36, 37, 38, 39].include? tax.taxauthid } selected.each { |tax| puts "#{tax.taxamount} - #{tax.taxauthid}" }

Bryan

8

In most cases that I see (according to the Pickaxe) this is "Case Equality" that is just a synonym to ==.

9

Craig White wrote:

Even my pickaxe book suggests this should work but it doesn't...

for tax in @taxes   next if ! (tax.taxauthid === [ 24, 25, 26, 27, 36, 37, 38, 39])   print tax.taxamount + " - " + tax.taxauthid + "\n" end

and my thinking is that if the tax.taxauthid is not found in the set of values, it should jump to the next value of tax.

Why doesn't this work?

Well, if you're trying to use Array#===, then the array needs to be on the *left* side of the operator. But I agree that this is an ugly way of doing things. Probably better is:

@taxes.select{|tax| [24, 25, 26, ...].include? tax.taxauthid}.each do

tax>

  # print stuff end

Best,

10

Craig White wrote: > Even my pickaxe book suggests this should work but it doesn't... > > for tax in @taxes > next if ! (tax.taxauthid === [ 24, 25, 26, 27, 36, 37, 38, 39]) > print tax.taxamount + " - " + tax.taxauthid + "\n" > end > > and my thinking is that if the tax.taxauthid is not found in the set of > values, it should jump to the next value of tax. > > Why doesn't this work?

Well, if you're trying to use Array#===, then the array needs to be on the *left* side of the operator. But I agree that this is an ugly way of doing things. Probably better is:

@taxes.select{|tax| [24, 25, 26, ...].include? tax.taxauthid}.each do >tax>   # print stuff end

11

Craig White wrote: [...] > yes, thanks...the .include? worked

Great.

> where the comparison operator === did > not work for me (or at least I gave up trying)

Why do you say it still didn't work? I explained in my previous message *exactly* how to get === to work. Please read text, not just code samples. :slight_smile:

12

I'd bet I'm not the only one waiting to see your beautiful code. ;p

Pepe