PowerShell (4) Object

终于把Object有关的看完了。下面将是script的syntax。再然后是一些更advanced的topic。不过明天我就要happy去了。等回来咱们再一起学习。今天头还问我夏天什么打算，她还觉得我干的挺好，生怕夏天就走人了，唉，在SQL Server的时候比这忙多了，也不见什么人说声好。vendor和全职的区别呀。

8. Creating a New Object

Using New-Object

New_Object will call the proper constructor to create the object.

Get list of constructors for a type/class:

[System.String].GetConstructors() |   ForEach-Object { $_.toString() }

You can create an object on the fly:

  • First you need a new and empty object: $pocketknife = New-Object Object
  • # Adding a new property: describe the object

Add-Member -memberType NoteProperty -name Color -valueRed -inputObject $pocketknife

  • Adding Methods: define actions that the objectcan take

Add-Member -memberTypeScriptMethod -In $pocketknife -name cut -Value { “I’m whittling now”}

 

Tricks:

  • Specify arguments without parameter names by position data:

Most PowerShell cmdlets canreceive their input objects either by parameter (-inputObject) or via thepipeline, so you can add properties to your object in yet another way:

Add-Member -inputObject$pocketknife NoteProperty Manufacturer Idera

Add-Member -in $pocketknifeScriptMethod screw { “Phew…it’s in!” }

  • Specify “inputObject” through the pipeline:

$pocketknife | Add-MemberNoteProperty Blades 3

$pocketknife | Add-MemberScriptMethod corkscrew { “Pop! Cheers!” }

 

To use any of the methods, add a dot and then the method name followed by two parentheses,which are what distinguish properties from methods.

$objname.methodName()

Without (), it will list the description of methodName.

Type conversion

[System.DateTime]$date = “November1, 2007”

This willconvert String(default type) to DateTime.

 

Query object

Object property

Object type

MemberType Description
AliasProperty Alternative name for a property that already exists
CodeProperty Static .NET method returns property contents, such as get_ method
Property Genuine property
NoteProperty Subsequently added property with set data value
ScriptProperty Subsequently added property whose value is calculated by a script
ParameterizedProperty Property requiring additional arguments

 

List all properties

  • $host | Get-Member -memberType property
  • $host.ui.RawUI | Get-Member -memberType Property

 

List Enum values:

  • [System.Enum]::GetNames([System.ConsoleColor])

 

Object method

Method type

MemberType Description
CodeMethod Method mapped to a static .NET method
Method Genuine method
ScriptMethod Method invokes PowerShell code

List all method

$object | Get-Member -memberType *method

List static methods

[System.DateTime] | Get-Member -static -memberType *method

Several Method “Signatures”

 

Some methods accept different argument types or evendifferent numbers of arguments. To find out which “signatures” a methodsupports, use Get-Member again and look at the Definition property:

 

$info = $host.UI | Get-MemberWriteLine

$info.Definition

 

Every single PowerShell command returns objects. Storethe result in variable for easy access later.

 

Using method

Static method

[object type]::methodname()

For example:

  • [System.DateTime]::get_Now()
  • [System.DateTime]::Now
  • [System.DateTime]::isLeapYear(2010)
  • [Math]::Sqrt(64)

Operator

If a method begins with “op_”, it’s an operator, you can usethe method name or use corresponding operator:

Operator method Cooresponding operator
op_Addition +
op_Subtraction –
op_LessThanOrEqual -le
op_LessThan -lt
op_Inequality -eq
op_GreaterThanOrEqual -ge
op_GreaterThan -gt

 

Dynamic object instance members

$objName.method(paralist)

Example:

#Download address of a file:
$address = “http://powershell.com/cs/media/p/467/download.aspx”

#Save the file to this location:
$target = “$home\chart_drive_space.V2.ps1”

#Carry out download:
$object = New-Object Net.WebClient
$object.DownloadFile($address, $target)
“Filewas downloaded!”

List asymblies to search forinteresting types

Current application domain

[AppDomain]::CurrentDomain

Find intresting classes/types

$searchtext = “*Environment*”
[AppDomain]::CurrentDomain.GetAssemblies() |
ForEach-Object { $_.GetExportedTypes() } |
Where-Object { $_ -like $searchtext } |
ForEach-Object { $_.FullName }

 

Load more assembly

[void][reflection.assembly]::LoadWithPartialName(“Microsoft.VisualBasic”)

Using COM object

What are available?

Dir REGISTRY::HKEY_CLASSES_ROOT\CLSID -include PROGID -recurse |
foreach {$_.GetValue(“”)}

COM object issimilar to .Net object. It has properties and methods.

Following examplecreate a shortcut on Desktop:

# Create an object:
$wshell = New-Object -comObject WScript.Shell

# Assign a path to Desktop to the variable$path
$path = [system.Environment]::GetFolderPath(‘Desktop’)

# Create a link object
$link = $wshell.CreateShortcut(“$path\PowerShell.lnk”)

# $link is an object and has the propertiesand methods

$link.TargetPath = ‘powershell.exe’
$link.Description = ‘LaunchWindows PowerShell console’
$link.WorkingDirectory = $profile
$link.IconLocation = ‘powershell.exe’

# And save the changes using Save() method
$link.Save()