List is a generic type, which in simple terms just means it has a bit of a fluid definition. So, let's say we follow that recommendation from the ArrayList documentation, and want to use a generic List instead. Let's take a look at some fairly common methods of handling collections of items in PowerShell, shall we? Common Patterns Use of += to Build Arrays In the vast majority of cases, you're going to be handling arrays unless you deliberately choose to use another type of collection to handle output. Partially as a result of that, arrays (and more specifically object) are the backbone of PowerShell scripting. The main type of collection in use in PowerShell is the humble Array, at least in terms of what is often available directly from a script.īehind the murky curtain, PowerShell actually utilises the type quite heavily in its pipeline processor.

On the other side of things, IDictionary represents a less-strictly-ordered set of key/value pairs where a given key (often a string such as a name) is used to access the relevant item directly. NET Core: IList and IDictionary IList types represent a 'flat' collection, where it's simply an ordered list of items. Interfaces can get quite complex, and there are two main extensions of ICollection in use in.

One example of a collection that allows you to create synchronised versions, you can check out Hashtable and its static method Synchronized().įairly straightforward on the whole, I suppose.

It has the IsSynchronized and SyncRoot properties.įor collections that utilise this functionality, these can be used to determine whether a collection's state is synchronised across threads.It has a Count property that will give you the current number of items in that collection.It has a CopyTo() method that you can use to copy its items into an array of your choosing starting from the requested index.So for a type to be an ICollection, it needs to guarantee these things: ICollection is a fairly simple interface that has a few demands: It's a way of being able to define standard ways of interacting with more than one kind of object. In practical terms, an interface is a way of defining a required set of properties or methods that must be defined by any other type that wants to inherit from or implement this interface. That's a bit of a wordy definition, but it does the job. NET for those of you who're not familiar.įrom the C# Programming Guide's page on interfaces, we get this definition:Īn interface contains definitions for a group of related functionalities that a non-abstract class or a struct must implement.īy using interfaces, you can, for example, include behavior from multiple sources in a class. Let's look at what that actually means and take a quick refresher on what an interface actually is in. NET ecosystem, the term collection has a pretty well-defined meaning.Ī 'collection' is any type of object that implements the ICollection interface. Oftentimes, these items may be related to one another in some way. In its simplest usage, it just refers to a set of individual items. In general parlance, a collection is generally considered to be a pretty broad term.

The term collection is often bandied about, so let's define it concretely before we get started, shall we? Adding Many Items to an Existing Collection.I've also seen plenty of more experienced folks trip over it quite a lot, so here we are.īefore we begin, many thanks to Chris Dent for asking me to put this together and the basis for the recommendations at the end! So, let's take a look at a classic problem that never fails to confuse folks just getting into PowerShell. Trying to get back into the swing of things for 2020 now that I'm mostly settled in at my new job. Well, it's certainly been a while since I posted on here.

Icollections