duplicate behavior in powershell

Asked Sep 24 '20 at 01:06

Active Sep 24 '20 at 01:21

Viewed 58 times

I was just playing around with hash tables and I did this:

$C = @{color = [System.Collections.ArrayList]@(@{y = 'yellow'},@{y = 'blue'})}

and I ended up with finding I can do: ($C.color.y).Get(1) or ($C.color.y).Item(1) and it does exactly the same thing.

I also found even though the autocomplete doesn't show you can do this you can:

($C.color.y).Get(0).Contains('yellow')
($C.color.y).Get(1).Contains('blue')

The Get and Item methods appear to be interchangeable what is the difference between them? I did check the hash codes they are the same.

($C.color.y).Get(1).GetHashCode() or ($C.color.y).Item(1).GetHashCode()

edited Sep 24 '20 at 01:21

asked Sep 24 '20 at 01:06

Whitequill Riclo

What is `$C.color`? – Mathias R. Jessen Sep 24 '20 at 01:11
it's a hash table I made up. `$C` could be anything really. I just couldn't think of anything else to call it. – Whitequill Riclo Sep 24 '20 at 01:15
Are you sure? `[hashtable]` doesn't have a `Get` member, and has no overload for `Add()` taking a single argument. Can you show how you defined and populated `$C`? – Mathias R. Jessen Sep 24 '20 at 01:17
that should fix it. – Whitequill Riclo Sep 24 '20 at 01:22
it's a hashtable of a list of hashtables – Whitequill Riclo Sep 24 '20 at 01:25
3

Ahh, I see. This might be slightly confusing, but `$C.color` is not a hashtable - it's an `ArrayList` (containing hashtables). When you nest it in `()`, PowerShell interprets it as a _pipeline statement_, at which point it unravels the list - and the resulting value of `($C.color)` is therefore `[object[]]`. `[object[]]` (and all other array types) have a `Get()` method because someone thought it was a good idea - and also implement the `Item()` parameterized property to satisfy the [`IList` interface](https://learn.microsoft.com/en-us/dotnet/api/system.collections.ilist) – Mathias R. Jessen Sep 24 '20 at 01:28
I guess that makes enough sense. – Whitequill Riclo Sep 29 '20 at 03:50
can you give me where I can find more information about `[object[]]` is that from C#? – Whitequill Riclo Sep 29 '20 at 07:12

0 Answers0