SPARKNLP-835: Introduce ProtectedParam

src/main/scala/com/johnsnowlabs/nlp/HasProtectedParams.scala

@@ -0,0 +1,57 @@
+package com.johnsnowlabs.nlp
+
+import org.apache.spark.ml.param.{Param, Params}
+
+/** Enables a class to protect a parameter, which means that it can only be set once.
+  *
+  * This trait will enable a implicit conversion from Param to ProtectedParam. In addition, the
+  * new set for ProtectedParam will then check, whether or not the value was already set. If so,
+  * then a warning will be output and the value will not be set again.
+  */
+trait HasProtectedParams {
+  this: Params =>
+  implicit class ProtectedParam[T](private val param: Param[T])
+      extends Param[T](param.parent, param.name, param.doc, param.isValid) {
+
+    var isProtected = false
+
+    /** Sets this parameter to be protected, which means that it can only be set once.
+      *
+      * Default values do not count as a set value and can be overridden.
+      *
+      * @return
+      *   This object
+      */
+    def setProtected(): this.type = {
+      isProtected = true
+      this
+    }
+
+    def toParam: Param[T] = this.asInstanceOf[Param[T]]
+  }
+
+  /** Sets the value for a protected Param.
+    *
+    * If the parameter was already set, it will not be set again. Default values do not count as a
+    * set value and can be overridden.
+    *
+    * @param param
+    *   Protected parameter to set
+    * @param value
+    *   Value for the parameter
+    * @tparam T
+    *   Type of the parameter
+    * @return
+    *   This object
+    */
+  def set[T](param: ProtectedParam[T], value: T): this.type = {
+    if (param.isProtected && get(param).isDefined)
+      println(
+        s"Warning: The parameter ${param.name} is protected and can only be set once." +
+          " For a pretrained model, this was done during the initialization process." +
+          " If you are trying to train your own model, please check the documentation.")
+    else
+      set(param.toParam, value)
+    this
+  }
+}

src/main/scala/com/johnsnowlabs/nlp/embeddings/BertSentenceEmbeddings.scala

@@ -155,7 +155,8 @@ class BertSentenceEmbeddings(override val uid: String)
     with HasEmbeddingsProperties
     with HasStorageRef
     with HasCaseSensitiveProperties
-    with HasEngine {
+    with HasEngine
+    with HasProtectedParams {
 
   def this() = this(Identifiable.randomUID("BERT_SENTENCE_EMBEDDINGS"))
 
@@ -180,7 +181,7 @@ class BertSentenceEmbeddings(override val uid: String)
     * @group param
     */
   val maxSentenceLength =
-    new IntParam(this, "maxSentenceLength", "Max sentence length to process")
+    new IntParam(this, "maxSentenceLength", "Max sentence length to process").setProtected()
 
   /** Use Long type instead of Int type for inputs (Default: `false`)
     *
@@ -190,15 +191,14 @@ class BertSentenceEmbeddings(override val uid: String)
     parent = this,
     name = "isLong",
     "Use Long type instead of Int type for inputs buffer - Some Bert models require Long instead of Int.")
+    .setProtected()
 
   /** set isLong
     *
     * @group setParam
     */
   def setIsLong(value: Boolean): this.type = {
-    if (get(isLong).isEmpty)
-      set(this.isLong, value)
-    this
+    set(this.isLong, value)
   }
 
   /** get isLong
@@ -223,9 +223,7 @@ class BertSentenceEmbeddings(override val uid: String)
     * @group setParam
     */
   override def setDimension(value: Int): this.type = {
-    if (get(dimension).isEmpty)
-      set(this.dimension, value)
-    this
+    set(this.dimension, value)
 
   }
 
@@ -234,9 +232,7 @@ class BertSentenceEmbeddings(override val uid: String)
     * @group setParam
     */
   override def setCaseSensitive(value: Boolean): this.type = {
-    if (get(caseSensitive).isEmpty)
-      set(this.caseSensitive, value)
-    this
+    set(this.caseSensitive, value)
   }
 
   /** Vocabulary used to encode the words to ids with WordPieceEncoder
@@ -262,9 +258,7 @@ class BertSentenceEmbeddings(override val uid: String)
       value <= 512,
       "BERT models do not support sequences longer than 512 because of trainable positional embeddings")
 
-    if (get(maxSentenceLength).isEmpty)
-      set(maxSentenceLength, value)
-    this
+    set(maxSentenceLength, value)
   }
 
   /** ConfigProto from tensorflow, serialized into byte array. Get with

src/test/scala/com/johnsnowlabs/nlp/HasFeaturesTestSpec.scala

@@ -18,7 +18,7 @@ class HasFeaturesTestSpec extends AnyFlatSpec {
 
   behavior of "HasFeatures"
 
-  it should "set protected params only once" taggedAs FastTest in {
+  it should "set protected features only once" taggedAs FastTest in {
     model.setProtectedMockFeature("first")
     assert(model.getProtectedMockFeature == "first")
 

src/test/scala/com/johnsnowlabs/nlp/HasProtectedParamsTestSpec.scala

@@ -0,0 +1,42 @@
+package com.johnsnowlabs.nlp
+
+import com.johnsnowlabs.nlp.serialization.StructFeature
+import com.johnsnowlabs.tags.FastTest
+import com.johnsnowlabs.util.TestUtils.captureOutput
+import org.apache.spark.ml.param.Param
+import org.scalatest.flatspec.AnyFlatSpec
+class HasProtectedParamsTestSpec extends AnyFlatSpec {
+  class MockModel extends AnnotatorModel[MockModel] with HasProtectedParams {
+    override val uid: String = "MockModel"
+    override val outputAnnotatorType: AnnotatorType = AnnotatorType.DUMMY
+    override val inputAnnotatorTypes: Array[AnnotatorType] = Array(AnnotatorType.DUMMY)
+
+    val protectedParam =
+      new Param[String](this, "MockString", "Mock protected Param").setProtected()
+    def setProtectedParam(value: String): this.type = {
+      set(protectedParam, value)
+    }
+
+    def getProtectedParam: String = {
+      $(protectedParam)
+    }
+
+  }
+
+  val model = new MockModel
+
+  behavior of "HasProtectedParams"
+
+  it should "set protected params only once" taggedAs FastTest in {
+    model.setProtectedParam("first")
+
+    assert(model.getProtectedParam == "first")
+
+    val output = captureOutput {
+      model.setProtectedParam("second")
+
+    }
+    assert(output.contains("is protected and can only be set once"))
+    assert(model.getProtectedParam == "first")
+  }
+}