BREAKING: V2 candidate, add caching of properties not in desired state (#39)

dan-hughes · web-flow · commit d7c5fbe1a43e · 2025-07-06T21:29:29.000+02:00
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -10,6 +10,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `azure-pipelines.yml`
   - Remove `windows-2019` images fixes [#43](https://github.com/dsccommunity/DscResource.Base/issues/43)
   - Move individual tasks to `windows-latest`.
+- `ResourceBase`
+  - Cache properties not in desired state.
+  - Make `Set()` call `Test()` and `Test()` call `Get()`.
+
+### Removed
+
+- `ResourceBase`
+  - Remove `Compare()` method as not used.
+  - Removed feature flags and alternate behavior.
 
 ## [1.4.0] - 2025-05-24
 
diff --git a/source/Classes/010.ResourceBase.ps1 b/source/Classes/010.ResourceBase.ps1
@@ -19,8 +19,14 @@ class ResourceBase
     # Property for derived class to set properties that should not be enforced.
     hidden [System.String[]] $ExcludeDscProperties = @()
 
-    # Property for derived class to enable Enums to be used as optional properties. The usable Enum values should start at value 1.
-    hidden [System.Boolean] $FeatureOptionalEnums = $false
+    # Property for holding the properties that are not in desired state.
+    hidden [System.Collections.Hashtable[]] $PropertiesNotInDesiredState = @()
+
+    # Property for holding the desired state.
+    hidden [System.Collections.Hashtable] $CachedDesiredState = $null
+
+    # Property for holding the key properties.
+    hidden [System.Collections.Hashtable] $CachedKeyProperties = $null
 
     # Default constructor
     ResourceBase()
@@ -58,16 +64,17 @@ class ResourceBase
 
     [ResourceBase] Get()
     {
+        $this.SetCachedKeyProperties()
+
+        $this.CachedDesiredState = $this.GetDesiredState()
+
         $this.Normalize()
 
         $this.Assert()
 
-        # Get all key properties.
-        $keyProperty = $this | Get-DscProperty -Attribute 'Key'
-
-        Write-Verbose -Message ($this.localizedData.GetCurrentState -f $this.GetType().Name, ($keyProperty | ConvertTo-Json -Compress))
+        Write-Verbose -Message ($this.localizedData.GetCurrentState -f $this.GetType().Name, ($this.CachedKeyProperties | ConvertTo-Json -Compress))
 
-        $getCurrentStateResult = $this.GetCurrentState($keyProperty)
+        $getCurrentStateResult = $this.GetCurrentState($this.CachedKeyProperties)
 
         $dscResourceObject = [System.Activator]::CreateInstance($this.GetType())
 
@@ -83,12 +90,13 @@ class ResourceBase
         $keyPropertyAddedToCurrentState = $false
 
         # Set key property values unless it was returned from the derived class' GetCurrentState().
-        foreach ($propertyName in $keyProperty.Keys)
+        foreach ($propertyName in $this.CachedKeyProperties.Keys)
         {
             if ($propertyName -notin @($getCurrentStateResult.Keys))
             {
                 # Add the key value to the instance to be returned.
                 $dscResourceObject.$propertyName = $this.$propertyName
+                $getCurrentStateResult.$propertyName = $this.$propertyName
 
                 $keyPropertyAddedToCurrentState = $true
             }
@@ -117,7 +125,7 @@ class ResourceBase
             Returns all enforced properties not in desired state, or $null if
             all enforced properties are in desired state.
         #>
-        $propertiesNotInDesiredState = $this.Compare($getCurrentStateResult, @())
+        $this.PropertiesNotInDesiredState = $this.Compare($getCurrentStateResult, @())
 
         <#
             Return the correct values for Reasons property if the derived DSC resource
@@ -126,7 +134,7 @@ class ResourceBase
         if (($this | Test-DscProperty -Name 'Reasons') -and -not $getCurrentStateResult.ContainsKey('Reasons'))
         {
             # Always return an empty array if all properties are in desired state.
-            $dscResourceObject.Reasons = $propertiesNotInDesiredState |
+            $dscResourceObject.Reasons = $this.PropertiesNotInDesiredState |
                 Resolve-Reason -ResourceName $this.GetType().Name |
                 ConvertFrom-Reason
         }
@@ -137,53 +145,38 @@ class ResourceBase
 
     [void] Set()
     {
-        # Get all key properties.
-        $keyProperty = $this | Get-DscProperty -Attribute 'Key'
-
-        Write-Verbose -Message ($this.localizedData.SetDesiredState -f $this.GetType().Name, ($keyProperty | ConvertTo-Json -Compress))
+        Write-Verbose -Message ($this.localizedData.SetDesiredState -f $this.GetType().Name)
 
-        <#
-            Returns all enforced properties not in desires state, or $null if
-            all enforced properties are in desired state.
-        #>
-        $propertiesNotInDesiredState = $this.Compare()
-
-        if ($propertiesNotInDesiredState)
-        {
-            $propertiesToModify = $propertiesNotInDesiredState | ConvertFrom-CompareResult
-
-            $propertiesToModify.Keys |
-                ForEach-Object -Process {
-                    Write-Verbose -Message ($this.localizedData.SetProperty -f $_, $propertiesToModify.$_)
-                }
-
-            <#
-                Call the Modify() method with the properties that should be enforced
-                and are not in desired state.
-            #>
-            $this.Modify($propertiesToModify)
-        }
-        else
+        if ($this.Test())
         {
             Write-Verbose -Message $this.localizedData.NoPropertiesToSet
+            return
         }
-    }
 
-    [System.Boolean] Test()
-    {
-        # Get all key properties.
-        $keyProperty = $this | Get-DscProperty -Attribute 'Key'
+        # $this.PropertiesNotInDesiredState was set by the Get() method.
+        # The Get() method is called by Test().
+        $propertiesToModify = $this.PropertiesNotInDesiredState | ConvertFrom-CompareResult
 
-        Write-Verbose -Message ($this.localizedData.TestDesiredState -f $this.GetType().Name, ($keyProperty | ConvertTo-Json -Compress))
+        $propertiesToModify.Keys |
+            ForEach-Object -Process {
+                Write-Verbose -Message ($this.localizedData.SetProperty -f $_, $propertiesToModify.$_)
+            }
 
         <#
-            Returns all enforced properties not in desired state, or $null if
-            all enforced properties are in desired state.
-            Will call Get().
+            Call the Modify() method with the properties that should be enforced
+            and are not in desired state.
         #>
-        $propertiesNotInDesiredState = $this.Compare()
+        $this.Modify($propertiesToModify)
+    }
 
-        if ($propertiesNotInDesiredState)
+    [System.Boolean] Test()
+    {
+        Write-Verbose -Message ($this.localizedData.TestDesiredState -f $this.GetType().Name)
+
+        $null = $this.Get()
+
+        # $this.PropertiesNotInDesiredState was set by the Get() method.
+        if ($this.PropertiesNotInDesiredState)
         {
             Write-Verbose -Message $this.localizedData.NotInDesiredState
             return $false
@@ -199,30 +192,16 @@ class ResourceBase
         desired state.
 
         This method should normally not be overridden.
-    #>
-    hidden [System.Collections.Hashtable[]] Compare()
-    {
-        # Get the current state, all properties except Read properties .
-        $currentState = $this.Get() | Get-DscProperty -Attribute @('Key', 'Mandatory', 'Optional')
-
-        return $this.Compare($currentState, @())
-    }
-
-    <#
-        Returns a hashtable containing all properties that should be enforced and
-        are not in desired state, or $null if all enforced properties are in
-        desired state.
 
-        This method should normally not be overridden.
+        This method is only used by Get().
     #>
     hidden [System.Collections.Hashtable[]] Compare([System.Collections.Hashtable] $currentState, [System.String[]] $excludeProperties)
     {
-        $desiredState = $this.GetDesiredState()
-
+        # $this.CachedDesiredState was set by the Get() method.
         $CompareDscParameterState = @{
             CurrentValues     = $currentState
-            DesiredValues     = $desiredState
-            Properties        = $desiredState.Keys
+            DesiredValues     = $this.CachedDesiredState
+            Properties        = $this.CachedDesiredState.Keys
             ExcludeProperties = ($excludeProperties + $this.ExcludeDscProperties) | Select-Object -Unique
             IncludeValue      = $true
             # This is needed to sort complex types.
@@ -239,30 +218,26 @@ class ResourceBase
     # This method should normally not be overridden.
     hidden [void] Assert()
     {
-        $this.AssertProperties($this.GetDesiredState())
+        $this.AssertProperties($this.CachedDesiredState)
     }
 
     # This method should normally not be overridden.
     hidden [void] Normalize()
     {
-        $this.NormalizeProperties($this.GetDesiredState())
+        $this.NormalizeProperties($this.CachedDesiredState)
     }
 
     # This is a private method and should normally not be overridden.
     hidden [System.Collections.Hashtable] GetDesiredState()
     {
         $getDscPropertyParameters = @{
-            Attribute = @(
+            Attribute           = @(
                 'Key'
                 'Mandatory'
                 'Optional'
             )
-            HasValue  = $true
-        }
-
-        if ($this.FeatureOptionalEnums)
-        {
-            $getDscPropertyParameters.IgnoreZeroEnumValue = $true
+            HasValue            = $true
+            IgnoreZeroEnumValue = $true
         }
 
         # Get the properties that has a non-null value and is not of type Read.
@@ -271,6 +246,13 @@ class ResourceBase
         return $desiredState
     }
 
+    # This is a private method and should normally not be overridden.
+    hidden [void] SetCachedKeyProperties()
+    {
+        # Sets the key properties of the resource.
+        $this.CachedKeyProperties = $this | Get-DscProperty -Attribute 'Key'
+    }
+
     <#
         This method can be overridden if resource specific property asserts are
         needed. The parameter properties will contain the properties that are
diff --git a/source/en-US/ResourceBase.strings.psd1 b/source/en-US/ResourceBase.strings.psd1
@@ -6,8 +6,8 @@
 
 ConvertFrom-StringData @'
     GetCurrentState = Getting the current state for resource '{0}' using the key property '{1}'. (RB0001)
-    TestDesiredState = Determining the current state for resource '{0}' using the key property '{1}'. (RB0002)
-    SetDesiredState = Setting the desired state for resource '{0}' using the key property '{1}'. (RB0003)
+    TestDesiredState = Determining the current state for resource '{0}'. (RB0002)
+    SetDesiredState = Setting the desired state for resource '{0}'. (RB0003)
     NotInDesiredState = The current state is not the desired state. (RB0004)
     InDesiredState = The current state is the desired state. (RB0005)
     SetProperty = The property '{0}' will be set to '{1}'. (RB0006)
diff --git a/tests/Unit/Classes/ResourceBase.Tests.ps1 b/tests/Unit/Classes/ResourceBase.Tests.ps1
