PowerShell Classes 5.0

Examples

• 5

  Listing available constructors for a class

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  5

  5.0

  In PowerShell 5.0+ you can list available constructors by calling the static new-method without parentheses.

  PS> [DateTime]::new
  
  OverloadDefinitions
  -------------------
  datetime new(long ticks)
  datetime new(long ticks, System.DateTimeKind kind)
  datetime new(int year, int month, int day)
  datetime new(int year, int month, int day, System.Globalization.Calendar calendar)
  datetime new(int year, int month, int day, int hour, int minute, int second)
  datetime new(int year, int month, int day, int hour, int minute, int second, System.DateTimeKind kind)
  datetime new(int year, int month, int day, int hour, int minute, int second, System.Globalization.Calendar calendar)
  datetime new(int year, int month, int day, int hour, int minute, int second, int millisecond)
  datetime new(int year, int month, int day, int hour, int minute, int second, int millisecond, System.DateTimeKind kind)
  datetime new(int year, int month, int day, int hour, int minute, int second, int millisecond,
  System.Globalization.Calendar calendar)
  datetime new(int year, int month, int day, int hour, int minute, int second, int millisecond,
  System.Globalization.Calendar calendar, System.DateTimeKind kind)
  

  This is the same technique that you can use to list overload definitions for any method

  > 'abc'.CompareTo
  
  OverloadDefinitions
  -------------------
  int CompareTo(System.Object value)
  int CompareTo(string strB)
  int IComparable.CompareTo(System.Object obj)
  int IComparable[string].CompareTo(string other)
  

  For earlier versions you can create your own function to list available constructors:

  function Get-Constructor {
      [CmdletBinding()]
      param(
          [Parameter(ValueFromPipeline=$true)]
          [type]$type
      )
  
      Process {
          $type.GetConstructors() | 
          Format-Table -Wrap @{
              n="$($type.Name) Constructors"
              e={ ($_.GetParameters() | % { $_.ToString() }) -Join ", " }
          }
      }
  }
  

  Usage:

  Get-Constructor System.DateTime    
  #Or [datetime] | Get-Constructor
  
  DateTime Constructors
  ---------------------
  Int64 ticks
  Int64 ticks, System.DateTimeKind kind
  Int32 year, Int32 month, Int32 day
  Int32 year, Int32 month, Int32 day, System.Globalization.Calendar calendar
  Int32 year, Int32 month, Int32 day, Int32 hour, Int32 minute, Int32 second
  Int32 year, Int32 month, Int32 day, Int32 hour, Int32 minute, Int32 second, System.DateTimeKind kind
  Int32 year, Int32 month, Int32 day, Int32 hour, Int32 minute, Int32 second, System.Globalization.Calendar calendar
  Int32 year, Int32 month, Int32 day, Int32 hour, Int32 minute, Int32 second, Int32 millisecond
  Int32 year, Int32 month, Int32 day, Int32 hour, Int32 minute, Int32 second, Int32 millisecond, System.DateTimeKind kind
  Int32 year, Int32 month, Int32 day, Int32 hour, Int32 minute, Int32 second, Int32 millisecond, System.Globalization.Cal
  endar calendar
  Int32 year, Int32 month, Int32 day, Int32 hour, Int32 minute, Int32 second, Int32 millisecond, System.Globalization.Cal
  endar calendar, System.DateTimeKind kind
  

  edited Sep 11 at 9:45

  

  

  

  
• 1

  Constructor overloading

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  1

  class Person {
      [string] $Name
      [int] $Age
  
      Person([string] $Name) {
          $this.Name = $Name
      }
  
      Person([string] $Name, [int]$Age) {
          $this.Name = $Name
          $this.Age = $Age
      }
  }
  

  created Jul 21 at 16:20

  
• 1

  Methods and properties

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  1

  class Person {
      [string] $FirstName
      [string] $LastName
      [string] Greeting() {
          return "Greetings, {0} {1}!" -f $this.FirstName, $this.LastName
      }
  }
  
  $x = [Person]::new()
  $x.FirstName = "Jane"
  $x.LastName = "Doe"
  $greeting = $x.Greeting() # "Greetings, Jane Doe!"
  

  created Jul 21 at 16:20

  
• 0

  Basic Class Template

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  0

  # Define a class
  class TypeName
  {
     # Property with validate set
     [ValidateSet("val1", "Val2")]
     [string] $P1
  
     # Static property
     static [hashtable] $P2
  
     # Hidden property does not show as result of Get-Member
     hidden [int] $P3
  
     # Constructor
     TypeName ([string] $s)
     {
         $this.P1 = $s       
     }
  
     # Static method
     static [void] MemberMethod1([hashtable] $h)
     {
         [TypeName]::P2 = $h
     }
  
     # Instance method
     [int] MemberMethod2([int] $i)
     {
         $this.P3 = $i
         return $this.P3
     }
  }
  

  created Sep 5 at 20:27

  
• 0

  Get All Members of an Instance

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  0

  PS > Get-Member -InputObject $anObjectInstance
  

  This will return all members of the type instance. Here is a part of a sample output for String instance

     TypeName: System.String
  
  Name             MemberType            Definition
  ----             ----------            ----------
  Clone            Method                System.Object Clone(), System.Object ICloneable.Clone()
  CompareTo        Method                int CompareTo(System.Object value), int CompareTo(string strB), i...
  Contains         Method                bool Contains(string value)
  CopyTo           Method                void CopyTo(int sourceIndex, char[] destination, int destinationI...
  EndsWith         Method                bool EndsWith(string value), bool EndsWith(string value, System.S...
  Equals           Method                bool Equals(System.Object obj), bool Equals(string value), bool E...
  GetEnumerator    Method                System.CharEnumerator GetEnumerator(), System.Collections.Generic...
  GetHashCode      Method                int GetHashCode()
  GetType          Method                type GetType()
  ...
  

  created Jul 22 at 10:56