Is ds_Store supposed to be invisible?

Targets macOS
1

I run this code and get a nil object on the last item

itemF is the folder

var fcnt As Integer = itemF.Count
fSerch = fdirs(fdirs.LastIndex)//or the filename being looked for
For i = 0 To fcnt
   If itemF.ChildAt(i).Visible And fSerch = itemF.ChildAt(i).Name Then
    Return 0
  End If
Next

Whatever file could throw a nil object for equating the name, but be visible?

2

You can’t have i go from 0 to itemF.Count – off-by-one error. You want to initialize it to itemF.count-1. Count is the number of items, but they are indexed from 0 to Count-1.

Not sure what it has to do with .DS_Store, but yes, that’s invisible in the Finder but will still show up if you iterate over all of the items in the folder this way.

1 Like
3

So. It’s 0-based not 1. Wish it said that.

Thank you.

4

I was surprised it didn’t explicitly say that, but the ChildAt docs do call it an index and the examples all use .ChildAt(0) so one could infer the first entry is zero and indeed your code block starts at zero. So from 0 to itemF.Count would indeed attempt to access one index position too many.

In API 2 – where ChildAt() was introduced – Xojo has standardized on starting with 0 which is actually an improvement in consistency versus API 1 where the similar property was .Item() and started at 1 while some other things started at 0.

So in API 2 – what you should be using now for new code, expect things to start at 0 unless you very explicitly see it telling you otherwise. You may find code samples in older code which do have loops starting at 1 instead of 0. But you’ll find they use different names (like this .ChildAt vs the prior .Item) or a string substring using .Mid – which is 1-based – versus the API 2 .Middle which is 0-based.

Hope this helps – it is meant in a spirit of helping you with similar things in the future.

5

Interesting, I’d have though you’d get an OutOfBoundsException on the itemF.ChildAt(i).Visible and not a NOE.

1 Like
6

Yes, me too. It implies you can avoid both exceptions if you just check for nil and avoid accessing the item (which the original code does not do).

7

Sorry I couldn’t remember out of bounds. I have a lousy memory.

8

and DS_Store is not invisible (never).

9

Hmm… Out of memory, then :wink:

1 Like
10

You’re saying that because of the missing dot in the start of the file name? Yes, a typo since the beginning of this thread.

1 Like
11

Yes, that, and sometimes I download files from some webs file servers that remove the leading dot :wink:

So, sometimes I have DS_Store files and they are visibles.

12

Probably misconfigured servers, I’d think. :face_with_raised_eyebrow: