added way to store userInfo in DataStack and in transactions

Sources/Setup/DataStack.swift

@@ -442,6 +442,43 @@ public final class DataStack: Equatable {
     }
     
     
+    // MARK: 3rd Party Utilities
+    
+    /**
+     Allow external libraries to store custom data in the `DataStack`. App code should rarely have a need for this.
+     ```
+     enum Static {
+        static var myDataKey: Void?
+     }
+     CoreStore.defaultStack[userInfoKey: &Static.myDataKey] = myObject
+     ```
+     - Important: Do not use this method to store thread-sensitive data.
+     - parameter userInfoKey: the key for custom data. Make sure this is a static pointer that will never be changed.
+     - returns: A custom data identified by  `userInfoKey`
+     */
+    public subscript(userInfoKey key: UnsafeRawPointer) -> Any? {
+        
+        get {
+            
+            self.userInfoLock.lock()
+            defer {
+                
+                self.userInfoLock.unlock()
+            }
+            return self.userInfo[key]
+        }
+        set {
+            
+            self.userInfoLock.lock()
+            defer {
+                
+                self.userInfoLock.unlock()
+            }
+            self.userInfo[key] = newValue
+        }
+    }
+    
+    
     // MARK: Equatable
     
     public static func == (lhs: DataStack, rhs: DataStack) -> Bool {
@@ -571,6 +608,8 @@ public final class DataStack: Equatable {
     
     private var persistentStoresByFinalConfiguration = [String: NSPersistentStore]()
     private var finalConfigurationsByEntityIdentifier = [EntityIdentifier: Set<String>]()
+    private var userInfo: [UnsafeRawPointer: Any] = [:]
+    private let userInfoLock = NSRecursiveLock()
     
     deinit {
         

Sources/Transactions/BaseDataTransaction.swift

@@ -438,6 +438,43 @@ public /*abstract*/ class BaseDataTransaction {
     }
     
     
+    // MARK: 3rd Party Utilities
+    
+    /**
+     Allow external libraries to store custom data in the transaction. App code should rarely have a need for this.
+     ```
+     enum Static {
+     static var myDataKey: Void?
+     }
+     transaction[userInfoKey: &Static.myDataKey] = myObject
+     ```
+     - Important: Do not use this method to store thread-sensitive data.
+     - parameter userInfoKey: the key for custom data. Make sure this is a static pointer that will never be changed.
+     - returns: A custom data identified by  `userInfoKey`
+     */
+    public subscript(userInfoKey key: UnsafeRawPointer) -> Any? {
+        
+        get {
+            
+            self.userInfoLock.lock()
+            defer {
+                
+                self.userInfoLock.unlock()
+            }
+            return self.userInfo[key]
+        }
+        set {
+            
+            self.userInfoLock.lock()
+            defer {
+                
+                self.userInfoLock.unlock()
+            }
+            self.userInfo[key] = newValue
+        }
+    }
+    
+    
     // MARK: Internal
     
     internal let context: NSManagedObjectContext
@@ -476,4 +513,10 @@ public /*abstract*/ class BaseDataTransaction {
         
         return self.bypassesQueueing || self.transactionQueue.cs_isCurrentExecutionContext()
     }
+    
+    
+    // MARK: Private
+    
+    private var userInfo: [UnsafeRawPointer: Any] = [:]
+    private let userInfoLock = NSRecursiveLock()
 }