For - next loop

Rails
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

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2

2009/7/29 Craig W. [email protected]:

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

2009/7/29 Craig W. [email protected]:

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

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

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

8

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

9

Craig W. 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,

Marnen Laibow-Koser
http://www.marnen.org
[email protected]

10

Craig W. 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:

Craig

Best,

Marnen Laibow-Koser
http://www.marnen.org
[email protected]

11

On Wed, 2009-07-29 at 17:14 +0200, Marnen Laibow-Koser wrote:

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

yes, thanks…the .include? worked where the comparison operator === did
not work for me (or at least I gave up trying)

Craig

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12

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

Pepe

13

On Wed, 2009-07-29 at 19:30 +0200, Marnen Laibow-Koser wrote:

exactly how to get === to work. Please read text, not just code
samples. :slight_smile:

I said I gave up trying…I think you are probably correct but I am
struggling with find and ‘joins’ now which are far more important to me.
I was going to use this for/next loop thing but when I realized that
ez-where plugin was not just returning unneeded records but all records,
this became far less important for me.

Craig

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