{"id":8903,"date":"2015-03-18T06:00:00","date_gmt":"2015-03-18T13:00:00","guid":{"rendered":"http:\/\/www.sapien.com\/blog\/?p=8903"},"modified":"2016-04-08T16:31:57","modified_gmt":"2016-04-08T23:31:57","slug":"hidden-sort-of-the-hidden-keyword-in-windows-powershell-5-0-preview","status":"publish","type":"post","link":"https:\/\/dev.sapien.com\/blog\/2015\/03\/18\/hidden-sort-of-the-hidden-keyword-in-windows-powershell-5-0-preview\/","title":{"rendered":"Hidden … sort of: The Hidden Keyword in PowerShell Classes"},"content":{"rendered":"

The Hidden<\/strong> keyword hides properties and methods (and other members, like events) in a PowerShell class. When a member is hidden, you can still view and change it, but the Get-Member<\/strong> cmdlet doesn’t display it without the Force<\/strong> parameter and the hidden members are not available to auto-completion features, such as PrimalSense and IntelliSense.<\/p>\n

You can apply the Hidden<\/strong> keyword to any member (property, method, event, etc), including static members. It is not case sensitive and it can appear anywhere in the member signature before the member name. As a best practice, I suggest placing it first to simplify troubleshooting.<\/p>\n

I’ve spent quite a bit of time playing with classes in the Windows PowerShell 5.0. The ability to create and script with your own classes, and to create subclasses of those classes, is extremely powerful. I consider it to be the final frontier in the dev-ops continuum, so I’m determined to make sure that everyone understands it, even people who have no development background.<\/p>\n

One of the little quirks of scripted classes in Windows PowerShell is that all properties of instances of the class are public, visible, and read-write. When you add properties to a class, Windows PowerShell automatically creates special methods called accessors<\/em> that let users of the class get and set (view and change) the property values.<\/p>\n

For example, I’ll create a little Tree\u00a0class\u00a0with a Species property. At this point, I haven’t created any methods, not even constructors.<\/p>\n

class Tree\r\n{\r\n    [String] $Species\r\n}<\/pre>\n
When I create an instance of the Tree class…<\/p>\n
$myTree = [Tree]::new()<\/pre>\n
… Windows PowerShell\u00a0adds get_Species<\/strong> and set_Species<\/strong> accessor methods so you can view and change the Species<\/strong> property value. These methods are hidden, but you can see them when you use the Force parameter of Get-Member.<\/p>\n
PS C:\\> $myTree | Get-Member -Name \"*Species*\"\r\n\r\n   TypeName: Tree\r\n\r\nName    MemberType Definition               \r\n----    ---------- ----------               \r\nSpecies Property   string Species {get;set;}\r\n\r\n\r\n\r\nPS C:\\> $myTree | Get-Member -Name \"*Species*\" -Force\r\n\r\n   TypeName: Tree\r\n\r\nName        MemberType Definition               \r\n----        ---------- ----------               \r\nget_Species Method     string get_Species()     \r\nset_Species Method     void set_Species(string )\r\nSpecies     Property   string Species {get;set;}<\/pre>\n
In fact, every variable that you create in a class outside of a method becomes a property of that class with accessor methods to view and change it.<\/p>\n
For example, I’ve added a Height<\/strong> property and a Grow<\/strong> method to the Tree class, and a grow_times<\/strong> variable to hold the number of times that I’ve called the Grow<\/strong> method on my tree. But Windows PowerShell considers the grow_times<\/strong> variable to be a property, and adds get\/set methods for it to the class.<\/p>\n
class Tree\r\n{\r\n    # Properties\r\n    [String] $Species\r\n    [double] $Height\r\n\r\n    # Methods\r\n    [int] Grow ([int]$inches)\r\n    {\r\n        $this.Height += $inches\r\n        $this.grow_times++\r\n        return $this.Height\r\n    }\r\n\r\n    # Variables -- these are properties, too.\r\n    [int] $grow_times = 0\r\n}<\/pre>\n
When I create an instance of the Tree class, grow_times<\/strong> is a property with get and set accessor methods, just like Species<\/strong> and Height<\/strong>.<\/p>\n
PS C:\\> $myTree | Get-Member\r\n\r\nTypeName: Tree\r\n\r\nName\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 MemberType Definition\r\n----\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 ---------- ----------\r\nEquals\u00a0\u00a0\u00a0\u00a0\u00a0 Method\u00a0\u00a0\u00a0\u00a0 bool Equals(System.Object obj)\r\nGetHashCode Method\u00a0\u00a0\u00a0\u00a0 int GetHashCode()\r\nGetType\u00a0\u00a0\u00a0\u00a0 Method\u00a0\u00a0\u00a0\u00a0 type GetType()\r\nGrow\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Method\u00a0\u00a0\u00a0\u00a0 int Grow(int inches)\r\nToString\u00a0\u00a0\u00a0 Method\u00a0\u00a0\u00a0\u00a0 string ToString()\r\ngrow_times\u00a0 Property\u00a0\u00a0 int grow_times {get;set;}\r\nHeight\u00a0\u00a0\u00a0\u00a0\u00a0 Property\u00a0\u00a0 int Height {get;set;}\r\nSpecies\u00a0\u00a0\u00a0\u00a0 Property\u00a0\u00a0 string Species {get;set;}<\/pre>\n
 <\/p>\n
And, when I type $myTree<\/strong> and a dot, IntelliSense suggest the grow_times<\/strong> property, along with the other properties of the tree.<\/p>\n
\n
\"image\"<\/a><\/p>\n<\/blockquote>\n
I can’t make my variable completely private to the class \u2013 there is no Private keyword — but there is a Hidden<\/strong> keyword that hides members from auto-complete features and from Get-Member without \u2013Force.<\/p>\n
In this example, I add the Hidden<\/strong> keyword to the grow_times<\/strong> property. I can place\u00a0“Hidden”\u00a0anywhere in the statement before the name, that is, it can go before or after “[int]” or an attribute, but I think it’s best to place it first, especially for troubleshooting.<\/p>\n
class Tree\r\n{\r\n    # Properties\r\n    [String] $Species\r\n    [double] $Height\r\n\r\n    # Methods\r\n    [int] Grow ([int]$inches)\r\n    {\r\n        $this.Height += $inches\r\n        $this.grow_times++\r\n        return $this.Height\r\n    }\r\n\r\n    # Hidden properties\r\n    hidden [int] $grow_times = 0\r\n}<\/pre>\n
 <\/p>\n
Now, when I create a tree object and run Get-Member, the grow_times<\/strong> property is not displayed.<\/p>\n
\n
\"image\"<\/a><\/p>\n<\/blockquote>\n
The property is visible to Get-Member only with \u2013Force.<\/p>\n
PS C:\\> $myTree | Get-Member -MemberType Property\r\n\r\nTypeName: Tree\r\n\r\nName\u00a0\u00a0\u00a0 MemberType Definition\r\n----\u00a0\u00a0\u00a0 ---------- ----------\r\nHeight\u00a0 Property\u00a0\u00a0 int Height {get;set;}\r\nSpecies Property\u00a0\u00a0 string Species {get;set;}\r\n\r\n\r\nPS C:\\> $myTree | Get-Member -MemberType Property -Force\r\n\r\nTypeName: Tree\r\n\r\nName\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 MemberType Definition\r\n----\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 ---------- ----------\r\ngrow_times Property\u00a0\u00a0 int grow_times {get;set;}\r\nHeight\u00a0\u00a0\u00a0\u00a0 Property\u00a0\u00a0 int Height {get;set;}\r\nSpecies\u00a0\u00a0\u00a0 Property\u00a0\u00a0 string Species {get;set;}\r\n<\/pre>\n
 <\/p>\n
Users of the class can get and set the grow_times<\/strong> property, but only if they know about it. It is not advertised to them.\u00a0(You cannot override or redefine the property accessors.)<\/p>\n
PS C:\\> $myTree.grow_times\r\n0\r\n\r\nPS C:\\ps-test> $myTree.grow_times++\r\n\r\nPS C:\\ps-test> $myTree.grow_times\r\n1<\/pre>\n
 <\/p>\n
And, even though it is hidden, grow_times<\/strong> is available to all members of the class, including the Grow() method that increments it.<\/p>\n
PS C:\\> $myTree.Height = 10\r\n\r\nPS C:\\> $myTree.grow_times\r\n0\r\n\r\nPS C:\\> $myTree.Grow(2)\r\n12\r\n\r\nPS C:\\> $myTree.grow_times\r\n1<\/pre>\n
Windows PowerShell classes give you a whole new level of power. And, the Hidden keyword is a handy tool for making classes work the way you designed them.<\/p>\n
Update 4\/08\/2016<\/strong>: Bruce Payette, the PowerShell team language developer, explained that we don’t have a Private<\/strong> keyword because PowerShell uses PowerShell for debugging. If you were able to create a property that was invisible to PowerShell, you couldn’t debug it.<\/p>\n
June Blender is a technology evangelist at SAPIEN Technologies, Inc. You can reach her at <\/em>juneb@sapien.com<\/em><\/a> or follow her on Twitter at <\/em>@juneb_get_help<\/em><\/a>.<\/em><\/p>\n
——————————<\/p>\n
More SAPIEN blog posts about the Windows PowerShell 5.0 classes:<\/p>\n
Beyond custom objects- Create a .NET class<\/a>
\nEnumerated Types in Windows PowerShell 5.0<\/a>
\nFind variables with class<\/a>
\nCreating Objects in Windows PowerShell<\/a>
\nWhy Do We Need Constructors?<\/a>
\nInheritance in PowerShell Classes<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
The Hidden keyword hides properties and methods (and other members, like events) in a PowerShell class. When a member is hidden, you can still view and change it, but the Get-Member cmdlet doesn’t display it without the Force parameter and the hidden members are not available to auto-completion features, such as PrimalSense and IntelliSense. You […]<\/p>\n","protected":false},"author":31,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[1033,941,1092,25],"tags":[934,28,962],"class_list":["post-8903","post","type-post","status-publish","format-standard","hentry","category-classes-in-powershell-5-0","category-powershell-5-0","category-powershell-5-0-14279-1000","category-windows-powershell","tag-juneb","tag-powershell","tag-powershell5-0"],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/posts\/8903","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/users\/31"}],"replies":[{"embeddable":true,"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/comments?post=8903"}],"version-history":[{"count":22,"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/posts\/8903\/revisions"}],"predecessor-version":[{"id":11766,"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/posts\/8903\/revisions\/11766"}],"wp:attachment":[{"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/media?parent=8903"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/categories?post=8903"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dev.sapien.com\/blog\/wp-json\/wp\/v2\/tags?post=8903"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}