main

docs/document/Powershell/docs/Language/PSCustomObject.md

@@ -1,7 +1,23 @@
 # PSCustomObject
 
-Differ from HashTable, `[PSCustomObject]` is a representation for object literal.
-It 
+`PSCustomObject` is a minimal object representation over `System.Object`.
+Custom properties are allowed as `NoteProperty`.
+
+In the following example, the `PSCustomObject` created has the same member as default `[object]` except the NoteProperty `Foo`.
+
+```ps1
+[object]::new() | gm
+[PSCustomObject]@{ Foo = 'I am a NoteProperty!' } | gm
+```
+
+## Why Do We Need it
+
+Differ from HashTable as a dictionary, `[PSCustomObject]` is a representation for object literal.
+The must-know is **`[PSCustomObject]` maps to the same type as `[psobject]`, `System.Management.Automation.PSObject`.**
+The only valid usage is marking one HashTable as `System.Management.Automation.PSCustomObject`. Other possible usages of `[PSCustomObject]` is bascially pointless.
+
+> [!WARNING]
+> Do not use `PSCustomObject` case-sensitive keys matters, name of extended properties are not case-sensitive, use `HashTable` instead.
 
 ## Creation
 
@@ -32,15 +48,13 @@ Or use `New-Object`, but this might be slower.
 $obj = New-Object -TypeName PSObject -Property $table
 ```
 
-## Copy a PSCustomObject
-
-- Shallow copy
+## Shallow Copy
 
 ```ps1
 $john = [PSCustomObject] @{
     Name = 'John Smith' 
     Age = 18
 }
 
-$smith = $john.PSObject.Copy()
+$smith = $john.psobject.Copy()
 ```

docs/document/Powershell/docs/Type System/1.Overview.md

@@ -1,3 +1,5 @@
 # Overview
 
-- Intrinsic Members
+- Intrinsic Members: builtin members for all objects in PowerShell.
+- Extended Type System: how PowerShell append extra members over a PowerShell object.
+- Native Types: types always available in PowerShell.

docs/document/Powershell/docs/Type System/Intrinsic Members.md

@@ -0,0 +1,13 @@
+# Intrinsic Members
+
+All objects in PowerShell have five intrinsic members:
+
+- `psobject`: Reflection source of members.
+- `psbase`: a `MemberSet` containing members of the object being wrapped.
+- `psadapted`: adapted members added by ETS.
+- `psextended`: a `MemberSet` containing extended members **added at runtime**.
+- `pstypenames`: equivalent to `psobject.TypeNames`. A collection containing the type names of inheritance chain.
+
+```ps1
+
+```

docs/document/Powershell/docs/Type System/Type Casting & Checking.md

@@ -0,0 +1,30 @@
+# Type Casting & Checking
+
+## Casting
+
+Prepend a type accelerator or type name before a variable or expression.
+
+```ps1
+[System.IO.FileInfo[]](gci -file)
+```
+
+### Safe Casting & Convertion
+
+`-as` acts the similar as `as` in `C#`, it tries to convert object to target type, returns `$null` if failed.
+The left operand can be:
+- type name as string
+- type accelerator
+- type accelerator name as string 
+
+```ps1
+$foo -as [object]
+(Get-Date) -as 'string' # convert to date string
+(Get-Date) -as 'System.String'
+```
+
+> [!NOTE]
+> All objects can be casted to `string`.
+
+## Checking
+
+`-is` and `-isnot` acts the same as `is` and `is not` in `C#`.