diff --git a/CloudCoder/src/org/cloudcoder/app/client/CloudCoder.java b/CloudCoder/src/org/cloudcoder/app/client/CloudCoder.java
index d425921a..810e5078 100644
--- a/CloudCoder/src/org/cloudcoder/app/client/CloudCoder.java
+++ b/CloudCoder/src/org/cloudcoder/app/client/CloudCoder.java
@@ -23,7 +23,6 @@
 import org.cloudcoder.app.client.model.Session;
 import org.cloudcoder.app.client.model.StatusMessage;
 import org.cloudcoder.app.client.page.CloudCoderPage;
-import org.cloudcoder.app.client.page.CoursesAndProblemsPage2;
 import org.cloudcoder.app.client.page.CoursesAndProblemsPage3;
 import org.cloudcoder.app.client.page.DevelopmentPage;
 import org.cloudcoder.app.client.page.EditProblemPage;
@@ -174,7 +173,7 @@ public void onSuccess(User result) {
 						changePage(page);
 					} else {
 						// Default behavior: navigate to the home page
-						changePage(new CoursesAndProblemsPage2());
+						changePage(createPageForPageId(PageId.COURSES_AND_PROBLEMS, ""));
 					}
 				}
 			}
@@ -271,7 +270,7 @@ private CloudCoderPage createPageForPageId(PageId pageId) {
 			// This shouldn't happen (can't find page for Activity),
 			// but if it does, go to the courses and problems page.
 			GWT.log("Don't know what kind of page to create for " + pageId);
-			page = new CoursesAndProblemsPage2();
+			page = new CoursesAndProblemsPage3();
 			break;
 		}
 		return page;
diff --git a/CloudCoder/src/org/cloudcoder/app/client/page/EditProblemPage.java b/CloudCoder/src/org/cloudcoder/app/client/page/EditProblemPage.java
index fd246d1b..77d9cc3a 100644
--- a/CloudCoder/src/org/cloudcoder/app/client/page/EditProblemPage.java
+++ b/CloudCoder/src/org/cloudcoder/app/client/page/EditProblemPage.java
@@ -23,14 +23,16 @@
 import org.cloudcoder.app.client.model.PageId;
 import org.cloudcoder.app.client.model.PageStack;
 import org.cloudcoder.app.client.model.Session;
-import org.cloudcoder.app.client.model.StatusMessage; 
+import org.cloudcoder.app.client.model.StatusMessage;
 import org.cloudcoder.app.client.rpc.RPC;
 import org.cloudcoder.app.client.view.ChoiceDialogBox;
 import org.cloudcoder.app.client.view.EditBooleanField;
 import org.cloudcoder.app.client.view.EditDateField;
 import org.cloudcoder.app.client.view.EditDateTimeField;
+import org.cloudcoder.app.client.view.EditDummyButton;
 import org.cloudcoder.app.client.view.EditEnumField;
 import org.cloudcoder.app.client.view.EditModelObjectField;
+import org.cloudcoder.app.client.view.EditOptionalStringFieldWithAceEditor;
 import org.cloudcoder.app.client.view.EditStringField;
 import org.cloudcoder.app.client.view.EditStringFieldWithAceEditor;
 import org.cloudcoder.app.client.view.PageNavPanel;
@@ -50,6 +52,7 @@
 import org.cloudcoder.app.shared.model.ProblemLicense;
 import org.cloudcoder.app.shared.model.ProblemType;
 import org.cloudcoder.app.shared.model.TestCase;
+import org.cloudcoder.app.shared.util.EvaluatorUtil;
 import org.cloudcoder.app.shared.util.SubscriptionRegistrar;
 
 import com.google.gwt.core.shared.GWT;
@@ -95,6 +98,7 @@ private class UI extends ResizeComposite implements SessionObserver {
 		private Button addTestCaseButton;
 		private FlowPanel addTestCaseButtonPanel;
 		private ProblemAndTestCaseList problemAndTestCaseListOrig;
+		EditOptionalStringFieldWithAceEditor<IProblem> evaluatorEditor;
 		
 		public UI() {
 			this.dockLayoutPanel = new DockLayoutPanel(Unit.PX);
@@ -278,6 +282,63 @@ private void setLanguage() {
 			skeletonEditor.setEditorTheme(AceEditorTheme.VIBRANT_INK);
 			problemFieldEditorList.add(skeletonEditor);
 			
+			// In the editor for the evaluator, we keep the editor mode in sync
+			// with the problem type, like for the skeleton.
+			evaluatorEditor =
+					new EditOptionalStringFieldWithAceEditor<IProblem>("Evaluator code (only Python)", "Use custom evaluator", ProblemData.EVALUATOR) {
+						@Override
+						public void update() {
+							super.update();
+							setLanguage();
+						}
+						@Override
+						public void onModelObjectChange() {
+							setLanguage();
+						}
+						private void setLanguage() {
+							AceEditorMode editorMode = ViewUtil.getModeForLanguage(getModelObject().getProblemType().getLanguage());
+							setEditorMode(editorMode);
+							
+							if(EvaluatorUtil.isEvaluatorUsedForProblemType(getModelObject().getProblemType())) {
+								setEnabled(true);
+							} else {
+								setEnabled(false);
+							}
+						}
+						
+					};
+			evaluatorEditor.setEditorThemes(AceEditorTheme.VIBRANT_INK, AceEditorTheme.SOLARIZED_DARK);
+			problemFieldEditorList.add(evaluatorEditor);
+			
+			EditDummyButton<IProblem, String> defaultEvaluatorButton =
+					new EditDummyButton<IProblem, String>("Reset to default evaluator", ProblemData.EVALUATOR) {
+						@Override
+						public void onButtonClick() {
+							setField(EvaluatorUtil.getDefaultEvaluator(getModelObject()));
+							evaluatorEditor.update();
+						}
+
+						@Override
+						public void update() {
+							super.update();
+							setLanguage();
+						}
+						
+						@Override
+						public void onModelObjectChange() {
+							setLanguage();
+						}
+						
+						private void setLanguage() {
+							if(EvaluatorUtil.isEvaluatorUsedForProblemType(getModelObject().getProblemType())) {
+								setEnabled(true);
+							} else {
+								setEnabled(false);
+							}
+						}
+					};
+
+			problemFieldEditorList.add(defaultEvaluatorButton);
 			// We don't need an editor for schema version - problems/testcases are
 			// automatically converted to the latest version when they are imported.
 			
diff --git a/CloudCoder/src/org/cloudcoder/app/client/page/LoginPage.java b/CloudCoder/src/org/cloudcoder/app/client/page/LoginPage.java
index 26c9fb1e..4573036f 100644
--- a/CloudCoder/src/org/cloudcoder/app/client/page/LoginPage.java
+++ b/CloudCoder/src/org/cloudcoder/app/client/page/LoginPage.java
@@ -176,7 +176,7 @@ public void setPubTextInstitution(String result) {
 	
 	/**
 	 * Default constructor.
-	 * Will take the user to the {@link CoursesAndProblemsPage2}
+	 * Will take the user to the {@link CoursesAndProblemsPage3}
 	 * upon a successful login.
 	 */
 	public LoginPage() {
diff --git a/CloudCoder/src/org/cloudcoder/app/client/view/EditDummyButton.java b/CloudCoder/src/org/cloudcoder/app/client/view/EditDummyButton.java
new file mode 100644
index 00000000..82609f8a
--- /dev/null
+++ b/CloudCoder/src/org/cloudcoder/app/client/view/EditDummyButton.java
@@ -0,0 +1,118 @@
+// CloudCoder - a web-based pedagogical programming environment
+// Copyright (C) 2015, Andras Eisenberger
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package org.cloudcoder.app.client.view;
+
+import org.cloudcoder.app.client.page.EditProblemPage;
+import org.cloudcoder.app.shared.model.ModelObjectField;
+
+import com.google.gwt.event.dom.client.ClickEvent;
+import com.google.gwt.event.dom.client.ClickHandler;
+import com.google.gwt.user.client.ui.Button;
+import com.google.gwt.user.client.ui.Composite;
+import com.google.gwt.user.client.ui.FlowPanel;
+import com.google.gwt.user.client.ui.IsWidget;
+
+/**
+ * Implementation of {@link EditModelObjectField} which does not edit any
+ * field. It extends {@link EditModelObjectField}, because only these can be
+ * on the {@link EditProblemPage} UI.
+ * 
+ * @author Andras Eisenberger
+ */
+public abstract class EditDummyButton<ModelObjectType, FieldType>
+		extends EditModelObjectField<ModelObjectType, FieldType> {
+	
+	private class UI extends Composite {
+		private Button button;
+
+		public UI() {
+			FlowPanel panel = new FlowPanel();
+			panel.setStyleName("cc-fieldEditor");
+			
+			this.button = new Button(getDescription(), new ClickHandler() {
+		      public void onClick(ClickEvent event) {
+		        onButtonClick();
+		      }
+			});
+			button.setStyleName("cc-emphButton");
+			panel.add(button);
+			
+			initWidget(panel);
+		}
+		
+		public void setEnabled(boolean enabled) {
+			button.setEnabled(enabled);
+		}
+	}
+
+	private UI ui;
+
+	/**
+	 * Constructor.
+	 * 
+	 * @param desc the human-readable description of the field, which is also
+	 * the text of the button
+	 * @param field any of the fields, it doesn't touch it by default
+	 */
+	public EditDummyButton(String desc, ModelObjectField<? super ModelObjectType, FieldType> field) {
+		super(desc, field);
+		ui = new UI();
+	}
+	
+	/* (non-Javadoc)
+	 * @see org.cloudcoder.app.client.view.EditModelObjectField#getUI()
+	 */
+	@Override
+	public IsWidget getUI() {
+		return ui;
+	}
+
+	/* (non-Javadoc)
+	 * @see org.cloudcoder.app.client.view.EditModelObjectField#commit()
+	 */
+	@Override
+	public void commit() {
+	}
+
+	/* (non-Javadoc)
+	 * @see org.cloudcoder.app.client.view.EditModelObjectField#update()
+	 */
+	@Override
+	public void update() {
+	}
+	
+	/* (non-Javadoc)
+	 * @see org.cloudcoder.app.client.view.EditModelObjectField#isCommitError()
+	 */
+	@Override
+	public boolean isCommitError() {
+		// It's connected to no field, so no
+		return false;
+	}
+	
+	/**
+	 * Do this when the button is clicked
+	 */
+	public abstract void onButtonClick();
+	
+	/**
+	 * @param enabled whether the button should be enabled
+	 */
+	public void setEnabled(boolean enabled) {
+		ui.setEnabled(enabled);
+	}
+}
diff --git a/CloudCoder/src/org/cloudcoder/app/client/view/EditOptionalStringFieldWithAceEditor.java b/CloudCoder/src/org/cloudcoder/app/client/view/EditOptionalStringFieldWithAceEditor.java
new file mode 100644
index 00000000..4ec3916f
--- /dev/null
+++ b/CloudCoder/src/org/cloudcoder/app/client/view/EditOptionalStringFieldWithAceEditor.java
@@ -0,0 +1,258 @@
+// CloudCoder - a web-based pedagogical programming environment
+// Copyright (C) 2011-2012, Jaime Spacco <jspacco@knox.edu>
+// Copyright (C) 2011-2012, David H. Hovemeyer <david.hovemeyer@gmail.com>
+// Copyright (C) 2015, Andras Eisenberger
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package org.cloudcoder.app.client.view;
+
+import org.cloudcoder.app.shared.model.ModelObjectField;
+
+import com.google.gwt.core.client.GWT;
+import com.google.gwt.event.logical.shared.ValueChangeEvent;
+import com.google.gwt.event.logical.shared.ValueChangeHandler;
+import com.google.gwt.user.client.ui.CheckBox;
+import com.google.gwt.user.client.ui.FlowPanel;
+import com.google.gwt.user.client.ui.IsWidget;
+import com.google.gwt.user.client.ui.Label;
+
+import edu.ycp.cs.dh.acegwt.client.ace.AceEditor;
+import edu.ycp.cs.dh.acegwt.client.ace.AceEditorMode;
+import edu.ycp.cs.dh.acegwt.client.ace.AceEditorTheme;
+
+/**
+ * Edit an optional string field of a model object using an {@link AceEditor}.
+ * 
+ * @author Andras Eisenberger
+ */
+public class EditOptionalStringFieldWithAceEditor<ModelObjectType>
+		extends EditModelObjectField<ModelObjectType, String> {
+	
+	private class UI extends EditModelObjectFieldUI {
+		private CheckBox checkBox;
+		private AceEditor editor;
+		private boolean editorStarted;
+		private AceEditorMode currentMode;
+
+		public UI(String checkboxLabel) {
+			FlowPanel panel = new FlowPanel();
+			panel.setStyleName("cc-fieldEditor", true);
+			
+			Label label = new Label(getDescription());
+			label.setStyleName("cc-fieldEditorLabel", true);
+			panel.add(label);
+			
+			panel.add(getErrorLabel());
+
+			this.checkBox = new CheckBox(checkboxLabel);
+
+			this.editor = new AceEditor();
+			editor.setSize("600px", "300px");
+			
+			checkBox.addValueChangeHandler(new ValueChangeHandler<Boolean>() {
+				
+				@Override
+				public void onValueChange(ValueChangeEvent<Boolean> event) {
+					if(event.getValue()) {
+						editor.setReadOnly(false);
+						editor.setTheme(editorEnabledTheme);
+					} else {
+						editor.setReadOnly(true);
+						editor.setTheme(editorDisabledTheme);
+					}
+					
+				}
+			});
+			
+			panel.add(checkBox);
+			panel.add(editor);
+			editorStarted = false;
+			
+			initWidget(panel);
+		}
+
+		public boolean isEditorStarted() {
+			return editorStarted;
+		}
+
+		public void startEditor() {
+			editor.startEditor();
+			if (editorMode != null) {
+				editor.setMode(editorMode);
+				currentMode = editorMode;
+			}
+			
+			resetEditorTheme();
+			
+			if(checkBox.getValue()) {
+				editor.setReadOnly(false);
+			} else {
+				editor.setReadOnly(true);
+			}
+			
+			editor.setFontSize("14px");
+			editorStarted = true;
+		}
+
+		/**
+		 * @param editorReadOnly whether the editor should be read-only now
+		 */
+		public void resetEnabled() {
+			checkBox.setEnabled(enabled);
+		}
+
+		public void setText(String text) {
+			editor.setText(text);
+		}
+
+		public String getText() {
+			return editor.getText();
+		}
+
+		public void setCheckBox(boolean value) {
+			checkBox.setValue(value, true);
+		}
+
+		public boolean getCheckBox() {
+			return checkBox.getValue();
+		}
+
+		public void resetEditorMode() {
+			if (editorMode != null && editorMode != currentMode) {
+				editor.setMode(editorMode);
+				currentMode = editorMode;
+				GWT.log("Changing editor mode to " + editorMode);
+			}
+		}
+
+		public void resetEditorTheme() {
+			if(getCheckBox()) {
+				if (editorEnabledTheme != null) {
+					editor.setTheme(editorEnabledTheme);
+				}
+			} else {
+				if (editorDisabledTheme != null) {
+					editor.setTheme(editorDisabledTheme);
+				}
+			}
+		}
+	}
+
+	private AceEditorMode editorMode;
+	private AceEditorTheme editorEnabledTheme;
+	private AceEditorTheme editorDisabledTheme;
+	private boolean enabled = true;
+	private UI ui;
+
+	/**
+	 * Constructor.
+	 * 
+	 * @param desc human-readable description of field being edited
+	 * @param checkboxLabel label to display next to checkbox
+	 * @param field the {@link ModelObjectField} being edited
+	 */
+	public EditOptionalStringFieldWithAceEditor(String desc, String checkboxLabel, ModelObjectField<? super ModelObjectType, String> field) {
+		super(desc, field);
+		this.ui = new UI(checkboxLabel);
+	}
+	
+	/**
+	 * Set the editor mode.
+	 * 
+	 * @param editorMode the editorMode to set
+	 */
+	public void setEditorMode(AceEditorMode editorMode) {
+		this.editorMode = editorMode;
+		if (ui.isEditorStarted()) {
+			ui.resetEditorMode();
+		}
+	}
+	
+	/**
+	 * Set the editor theme.
+	 * 
+	 * @param editorTheme the editorTheme to set
+	 */
+	public void setEditorThemes(AceEditorTheme editorEnabledTheme, AceEditorTheme editorDisabledTheme) {
+		this.editorEnabledTheme = editorEnabledTheme;
+		this.editorDisabledTheme = editorDisabledTheme;
+		if (ui.isEditorStarted()) {
+			ui.resetEditorTheme();
+		}
+	}
+	
+	/**
+	 * @param enabled whether the editor should be enabled. Also unticks the
+	 * checkbox when disabled.
+	 */
+	public void setEnabled(boolean enabled) {
+		if(this.enabled != enabled) {
+			this.enabled = enabled;
+			ui.resetEnabled();
+			if(enabled) {
+				if(!ui.getText().trim().isEmpty()) {
+					ui.setCheckBox(true);
+				}
+			} else {
+				ui.setCheckBox(false);
+			}
+		}
+	}
+	
+	/* (non-Javadoc)
+	 * @see org.cloudcoder.app.client.view.EditModelObjectField#getUI()
+	 */
+	@Override
+	public IsWidget getUI() {
+		return ui;
+	}
+
+	/* (non-Javadoc)
+	 * @see org.cloudcoder.app.client.view.EditModelObjectField#commit()
+	 */
+	@Override
+	public void commit() {
+		String text;
+		if(ui.getCheckBox()) {
+			text = ui.getText();
+		} else {
+			text = "";
+		}
+		
+		if (text.length() > getModelObjectField().getSize()) {
+			setCommitError(true);
+			ui.setError("Value cannot be longer than " + getModelObjectField().getSize() + " characters");
+		} else {
+			setCommitError(false);
+			ui.clearError();
+			setField(text);
+		}
+	}
+
+	@Override
+	public void update() {
+		if (!ui.isEditorStarted()) {
+			// At this point, we'll assume that the UI has been added to the page DOM,
+			// so it's safe to start the AceEditor.
+			ui.startEditor();
+		}
+		
+		String field = getField();
+		ui.setText(getField());
+		if(!field.isEmpty()) {
+			ui.setCheckBox(true);
+		}
+	}
+}
diff --git a/CloudCoderBuilder2/.classpath b/CloudCoderBuilder2/.classpath
index 59a773ea..29fc9517 100644
--- a/CloudCoderBuilder2/.classpath
+++ b/CloudCoderBuilder2/.classpath
@@ -17,7 +17,7 @@
 	</classpathentry>
 	<classpathentry kind="con" path="org.eclipse.jdt.junit.JUNIT_CONTAINER/4"/>
 	<classpathentry combineaccessrules="false" kind="src" path="/CloudCoderModelClassesJSON"/>
-	<classpathentry kind="lib" path="lib/jython-standalone-2.5.3.jar"/>
+	<classpathentry kind="lib" path="lib/jython-standalone-2.7.0.jar"/>
 	<classpathentry kind="lib" path="lib/daemon-0.7.jar"/>
 	<classpathentry kind="output" path="bin"/>
 </classpath>
diff --git a/CloudCoderBuilder2/src/org/cloudcoder/builder2/pythonfunction/AddPythonFunctionScaffoldingBuildStep.java b/CloudCoderBuilder2/src/org/cloudcoder/builder2/pythonfunction/AddPythonFunctionScaffoldingBuildStep.java
index d2d8e226..26d36600 100644
--- a/CloudCoderBuilder2/src/org/cloudcoder/builder2/pythonfunction/AddPythonFunctionScaffoldingBuildStep.java
+++ b/CloudCoderBuilder2/src/org/cloudcoder/builder2/pythonfunction/AddPythonFunctionScaffoldingBuildStep.java
@@ -23,6 +23,7 @@
 import org.cloudcoder.app.shared.model.Problem;
 import org.cloudcoder.app.shared.model.ProblemType;
 import org.cloudcoder.app.shared.model.TestCase;
+import org.cloudcoder.app.shared.util.EvaluatorUtil;
 import org.cloudcoder.builder2.model.BuilderSubmission;
 import org.cloudcoder.builder2.model.IBuildStep;
 import org.cloudcoder.builder2.model.InternalBuilderException;
@@ -70,7 +71,15 @@ private ProgramSource addScaffolding(ProgramSource programSource, Problem proble
 		String programText = programSource.getProgramText();
 		test.append(programText + "\n");
 		programTextLength=StringUtil.countLines(programText);
-		int spaces=getIndentationIncrementFromPythonCode(programText);
+		
+		// Add code for evaluator
+		String evalText = problem.getEvaluator();
+		if(evalText.trim().isEmpty()) {
+			// Default evaluator if no evaluator is given
+			evalText = EvaluatorUtil.getDefaultPythonFunctionEvaluator(problem);
+		}
+		
+		test.append(evalText + "\n");
 
 		for (TestCase t : testCaseList) {
 			// each test case is a function that invokes the function being tested
@@ -92,11 +101,8 @@ private ProgramSource addScaffolding(ProgramSource programSource, Problem proble
 			// the test case passed, and a String containing the 
 			// actual output.  
 			//
-			test.append(indent(spaces)+"_output="+problem.getTestname() + 
-					"(" +t.getInput()+ ")\n");
-			test.append(indent(spaces)+"_expected=" + t.getOutput() + "\n");
-			test.append(indent(spaces)+"_result=(_expected == _output) if (type(_output) != float and type(_expected) != float) else (math.fabs(_output-_expected) < 0.00001)\n");
-			test.append(indent(spaces)+"return (_result, _output)\n");
+			String in = t.getInput();
+			test.append("  return _eval((" + in + (in.trim().isEmpty() ? "" : ",") + "), " + t.getOutput() + ")\n");
 		}
 		
 		// Convert to string, determine epilogue length
@@ -107,17 +113,4 @@ private ProgramSource addScaffolding(ProgramSource programSource, Problem proble
 		// Done!
 		return new ProgramSource(result, prologueLength, epilogueLength);
 	}
-
-	private int getIndentationIncrementFromPythonCode(String programText) {
-		//TODO: Figure out the indentation scheme of the student submitted programTest
-		return 2;
-	}
-
-	private String indent(int n) {
-		StringBuilder b=new StringBuilder();
-		for (int i=0; i<n; i++) {
-			b.append(' ');
-		}
-		return b.toString();
-	}
 }
diff --git a/CloudCoderBuilder2/tests/junit/org/cloudcoder/builder2/tests/res/compute_sum.json b/CloudCoderBuilder2/tests/junit/org/cloudcoder/builder2/tests/res/compute_sum.json
index bfadc332..bdaad343 100644
--- a/CloudCoderBuilder2/tests/junit/org/cloudcoder/builder2/tests/res/compute_sum.json
+++ b/CloudCoderBuilder2/tests/junit/org/cloudcoder/builder2/tests/res/compute_sum.json
@@ -1 +1 @@
-{"problem_data":{"problem_type":1,"testname":"compute_sum","brief_description":"compute the sum of two numbers","description":"<p>Write a function called <code>compute_sum<\/code> that\n    takes two parameters and returns their sum.<\/p>\n<p>Example calls:<\/p>\n<ul>\n    <li><code>compute_sum(2, 3)<\/code> =&gt; <code>5<\/code><\/li>\n    <li><code>compute_sum(4, -11)<\/code> =&gt; <code>-7<\/code><\/li>\n    <li><code>compute_sum(42, 0)<\/code> =&gt; <code>42<\/code><\/li>\n<\/ul>","skeleton":"","schema_version":4,"author_name":"David Hovemeyer","author_email":"dhovemey@ycp.edu","author_website":"http:\/\/faculty.ycp.edu\/~dhovemey","timestamp_utc":1377615525510,"license":1,"parent_hash":"","external_library_url":"","external_library_md5":""},"test_case_data_list":[{"test_case_name":"twoPlusThree","input":"2, 3","output":"5","secret":false},{"test_case_name":"fourPlusMinusEleven","input":"4, -11","output":"-7","secret":false},{"test_case_name":"fortyTwoPlusZero","input":"42, 0","output":"42","secret":false}]}
\ No newline at end of file
+{"problem_data":{"problem_type":1,"testname":"compute_sum","brief_description":"compute the sum of two numbers","description":"<p>Write a function called <code>compute_sum<\/code> that\n    takes two parameters and returns their sum.<\/p>\n<p>Example calls:<\/p>\n<ul>\n    <li><code>compute_sum(2, 3)<\/code> =&gt; <code>5<\/code><\/li>\n    <li><code>compute_sum(4, -11)<\/code> =&gt; <code>-7<\/code><\/li>\n    <li><code>compute_sum(42, 0)<\/code> =&gt; <code>42<\/code><\/li>\n<\/ul>","skeleton":"","schema_version":4,"author_name":"David Hovemeyer","author_email":"dhovemey@ycp.edu","author_website":"http:\/\/faculty.ycp.edu\/~dhovemey","timestamp_utc":1377615525510,"license":1,"parent_hash":"","external_library_url":"","external_library_md5":"","evaluator":""},"test_case_data_list":[{"test_case_name":"twoPlusThree","input":"2, 3","output":"5","secret":false},{"test_case_name":"fourPlusMinusEleven","input":"4, -11","output":"-7","secret":false},{"test_case_name":"fortyTwoPlusZero","input":"42, 0","output":"42","secret":false}]}
\ No newline at end of file
diff --git a/CloudCoderBuilder2/tests/junit/org/cloudcoder/builder2/tests/res/gravity.json b/CloudCoderBuilder2/tests/junit/org/cloudcoder/builder2/tests/res/gravity.json
index 19cced23..3adf1054 100644
--- a/CloudCoderBuilder2/tests/junit/org/cloudcoder/builder2/tests/res/gravity.json
+++ b/CloudCoderBuilder2/tests/junit/org/cloudcoder/builder2/tests/res/gravity.json
@@ -1 +1 @@
-{"problem_data":{"problem_type":1,"testname":"gravity","brief_description":"How far do objects travel when thrown off a building?","description":"<p>\nConsider the problem of trying to determine how far an object\nfalls when thrown from the top of a very tall building. Because\nthe building is on Earth, accelaration due to gravity should be \npart of your calculations (i.e., assume 9.8 m\/s^2 as the <em>G<\/em> \nconstant). To make the calculation reasonable, assume the \nbuilding is infinitely tall and located in a vacuum on Earth\n(i.e., ignore any forces due to friction, air-resistance, etc.).\n<\/p>\n\n<p>\nReturn the number of meters the object has fallen after \n<code>time<\/code> seconds have elapsed when the object is \nthrown with given initial velocity.\n<\/p>\n","skeleton":"def gravity (time, initalVelocity):\n    \"\"\"\n    return float indicating number of meters an object has fallen \n    after being thrown with an initial velocity (given in meters per\n    second) and after falling for time seconds\n    \"\"\"\n    # TODO: complete code here\n    ","schema_version":4,"author_name":"Kannan Raju","author_email":"kr88@duke.edu","author_website":"","timestamp_utc":1378456148639,"license":1,"parent_hash":"","external_library_url":"","external_library_md5":""},"test_case_data_list":[{"test_case_name":"t0","input":"0, 0","output":"0","secret":false},{"test_case_name":"t1","input":"1, 1","output":"5.9","secret":false},{"test_case_name":"t2","input":"1, 5","output":"9.9","secret":false},{"test_case_name":"t3","input":"3, 5","output":"59.1","secret":false},{"test_case_name":"t4","input":"3, 0","output":"44.1","secret":false},{"test_case_name":"t5","input":"3200, 0","output":"50176000.0","secret":false},{"test_case_name":"t6","input":"86400, 0","output":"36578304000.0","secret":false},{"test_case_name":"t7","input":"12.5, 20","output":"1015.625","secret":false},{"test_case_name":"t8","input":"12.5, 200","output":"3265.625","secret":false},{"test_case_name":"t9","input":"12.5, 2000","output":"25765.625","secret":false}]}
\ No newline at end of file
+{"problem_data":{"problem_type":1,"testname":"gravity","brief_description":"How far do objects travel when thrown off a building?","description":"<p>\nConsider the problem of trying to determine how far an object\nfalls when thrown from the top of a very tall building. Because\nthe building is on Earth, accelaration due to gravity should be \npart of your calculations (i.e., assume 9.8 m\/s^2 as the <em>G<\/em> \nconstant). To make the calculation reasonable, assume the \nbuilding is infinitely tall and located in a vacuum on Earth\n(i.e., ignore any forces due to friction, air-resistance, etc.).\n<\/p>\n\n<p>\nReturn the number of meters the object has fallen after \n<code>time<\/code> seconds have elapsed when the object is \nthrown with given initial velocity.\n<\/p>\n","skeleton":"def gravity (time, initalVelocity):\n    \"\"\"\n    return float indicating number of meters an object has fallen \n    after being thrown with an initial velocity (given in meters per\n    second) and after falling for time seconds\n    \"\"\"\n    # TODO: complete code here\n    ","schema_version":4,"author_name":"Kannan Raju","author_email":"kr88@duke.edu","author_website":"","timestamp_utc":1378456148639,"license":1,"parent_hash":"","external_library_url":"","external_library_md5":"","evaluator":""},"test_case_data_list":[{"test_case_name":"t0","input":"0, 0","output":"0","secret":false},{"test_case_name":"t1","input":"1, 1","output":"5.9","secret":false},{"test_case_name":"t2","input":"1, 5","output":"9.9","secret":false},{"test_case_name":"t3","input":"3, 5","output":"59.1","secret":false},{"test_case_name":"t4","input":"3, 0","output":"44.1","secret":false},{"test_case_name":"t5","input":"3200, 0","output":"50176000.0","secret":false},{"test_case_name":"t6","input":"86400, 0","output":"36578304000.0","secret":false},{"test_case_name":"t7","input":"12.5, 20","output":"1015.625","secret":false},{"test_case_name":"t8","input":"12.5, 200","output":"3265.625","secret":false},{"test_case_name":"t9","input":"12.5, 2000","output":"25765.625","secret":false}]}
\ No newline at end of file
diff --git a/CloudCoderBuilder2/tests/junit/org/cloudcoder/builder2/tests/res/skip3.json b/CloudCoderBuilder2/tests/junit/org/cloudcoder/builder2/tests/res/skip3.json
index fb4b5652..7ff1df8e 100644
--- a/CloudCoderBuilder2/tests/junit/org/cloudcoder/builder2/tests/res/skip3.json
+++ b/CloudCoderBuilder2/tests/junit/org/cloudcoder/builder2/tests/res/skip3.json
@@ -1 +1 @@
-{"problem_data":{"problem_type":3,"testname":"skip 3","brief_description":"print integers in range, skipping by increments of 3","description":"<p>\n    The program will receive two integer input values,\n    <i>start<\/i> and <i>end<\/i>.  The\n    output of the program should be a line of text\n    with all of the integer values between\n    <i>start<\/i> and <i>end<\/i>, inclusive, such that\n    each successive integer is 3 greater than the previous\n    integer.\n<\/p>\n<p>\n    For example, if the input is <b>1 10<\/b>, then the output\n    should be\n<\/p>\n<blockquote><pre>1 4 7 10<\/pre><\/blockquote>\n<p>\n    Another example: if the input is <b>19 35<\/b>, then the\n    output should be\n<\/p>\n<blockquote><pre>19 22 25 28 31 34<\/pre><\/blockquote>\n<p>Hints:<\/p>\n<ul>\n    <li>The program already declares variables for <i>start<\/i>\n        and <i>end<\/i>, and uses <code>scanf<\/code> to read\n        their values<\/li>\n    <li>Make sure to print a space after each integer<\/li>\n    <li>Think about how to generate only every third integer;\n        <i>planning<\/i> the loop will be helpful<\/li>\n<\/ul>","skeleton":"#include <stdio.h>\n\nint main(void) {\n    \/\/ Declare variables for input (start and end)\n    int start, end;\n    \n    \/\/ Read input values\n    scanf(\"%i\", &start);\n    scanf(\"%i\", &end);\n    \n    \/\/ Use a loop to print the output values\n    \/\/ TODO\n    \n    return 0;\n}","schema_version":1,"author_name":"David Hovemeyer","author_email":"dhovemey@ycp.edu","author_website":"http:\/\/faculty.ycp.edu\/~dhovemey\/","timestamp_utc":1360782949618,"license":1,"parent_hash":"","external_library_url":"","external_library_md5":""},"test_case_data_list":[{"test_case_name":"OneToTenByThree","input":"1 10","output":"^(.*[^0-9])?1\\s+4\\s+7\\s+10([^0-9]*)?$","secret":false},{"test_case_name":"OneToTenPartialCredit","input":"1 10","output":"^(.*[^0-9])?1\\s+(2(\\s+3\\s+)?)?4\\s+(5(\\s+6\\s+)?)?7\\s+(8(\\s+9\\s+)?)?10([^0-9]*)?$","secret":false},{"test_case_name":"NineteenToThirtyFive","input":"19 35","output":"^(.*[^0-9])?19\\s+22\\s+25\\s+28\\s+31\\s+34([^0-9]*)?$","secret":false},{"test_case_name":"NineteenToThirtyFivePartialCredit","input":"19 35","output":"^(.*[^0-9])?19\\s+(20(\\s+21\\s+)?)?22\\s+(23(\\s+24\\s+)?)?25\\s+(26(\\s+27\\s+)?)?28\\s+(29(\\s+30\\s+)?)?31\\s+(32(\\s+33\\s+)?)?34(\\s+35)?([^0-9]*)?$","secret":false},{"test_case_name":"Just42","input":"42 42","output":"^(.*[^0-9])?42([^0-9]*)$","secret":false}]}
\ No newline at end of file
+{"problem_data":{"problem_type":3,"testname":"skip 3","brief_description":"print integers in range, skipping by increments of 3","description":"<p>\n    The program will receive two integer input values,\n    <i>start<\/i> and <i>end<\/i>.  The\n    output of the program should be a line of text\n    with all of the integer values between\n    <i>start<\/i> and <i>end<\/i>, inclusive, such that\n    each successive integer is 3 greater than the previous\n    integer.\n<\/p>\n<p>\n    For example, if the input is <b>1 10<\/b>, then the output\n    should be\n<\/p>\n<blockquote><pre>1 4 7 10<\/pre><\/blockquote>\n<p>\n    Another example: if the input is <b>19 35<\/b>, then the\n    output should be\n<\/p>\n<blockquote><pre>19 22 25 28 31 34<\/pre><\/blockquote>\n<p>Hints:<\/p>\n<ul>\n    <li>The program already declares variables for <i>start<\/i>\n        and <i>end<\/i>, and uses <code>scanf<\/code> to read\n        their values<\/li>\n    <li>Make sure to print a space after each integer<\/li>\n    <li>Think about how to generate only every third integer;\n        <i>planning<\/i> the loop will be helpful<\/li>\n<\/ul>","skeleton":"#include <stdio.h>\n\nint main(void) {\n    \/\/ Declare variables for input (start and end)\n    int start, end;\n    \n    \/\/ Read input values\n    scanf(\"%i\", &start);\n    scanf(\"%i\", &end);\n    \n    \/\/ Use a loop to print the output values\n    \/\/ TODO\n    \n    return 0;\n}","schema_version":1,"author_name":"David Hovemeyer","author_email":"dhovemey@ycp.edu","author_website":"http:\/\/faculty.ycp.edu\/~dhovemey\/","timestamp_utc":1360782949618,"license":1,"parent_hash":"","external_library_url":"","external_library_md5":"","evaluator":""},"test_case_data_list":[{"test_case_name":"OneToTenByThree","input":"1 10","output":"^(.*[^0-9])?1\\s+4\\s+7\\s+10([^0-9]*)?$","secret":false},{"test_case_name":"OneToTenPartialCredit","input":"1 10","output":"^(.*[^0-9])?1\\s+(2(\\s+3\\s+)?)?4\\s+(5(\\s+6\\s+)?)?7\\s+(8(\\s+9\\s+)?)?10([^0-9]*)?$","secret":false},{"test_case_name":"NineteenToThirtyFive","input":"19 35","output":"^(.*[^0-9])?19\\s+22\\s+25\\s+28\\s+31\\s+34([^0-9]*)?$","secret":false},{"test_case_name":"NineteenToThirtyFivePartialCredit","input":"19 35","output":"^(.*[^0-9])?19\\s+(20(\\s+21\\s+)?)?22\\s+(23(\\s+24\\s+)?)?25\\s+(26(\\s+27\\s+)?)?28\\s+(29(\\s+30\\s+)?)?31\\s+(32(\\s+33\\s+)?)?34(\\s+35)?([^0-9]*)?$","secret":false},{"test_case_name":"Just42","input":"42 42","output":"^(.*[^0-9])?42([^0-9]*)$","secret":false}]}
\ No newline at end of file
diff --git a/CloudCoderBuilderWebService/src/org/cloudcoder/builderwebservice/servlets/ProblemBuilder.java b/CloudCoderBuilderWebService/src/org/cloudcoder/builderwebservice/servlets/ProblemBuilder.java
index 77a93bea..84d4c8be 100644
--- a/CloudCoderBuilderWebService/src/org/cloudcoder/builderwebservice/servlets/ProblemBuilder.java
+++ b/CloudCoderBuilderWebService/src/org/cloudcoder/builderwebservice/servlets/ProblemBuilder.java
@@ -62,6 +62,7 @@ public Problem build() throws BadRequestException {
 		problem.setTimestampUtc(0L);
 		problem.setLicense(ProblemLicense.NOT_REDISTRIBUTABLE);
 		problem.setParentHash("");
+		problem.setEvaluator("");
 		
 		// None of the Problem-specific fields are significant
 		// Important: the builder must ignore the problem id.
diff --git a/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/EditProblemAdapter.java b/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/EditProblemAdapter.java
index 8d6e1a9a..e8b58b46 100644
--- a/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/EditProblemAdapter.java
+++ b/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/EditProblemAdapter.java
@@ -88,6 +88,17 @@ public String getSkeleton() {
 		return delegate.getSkeleton();
 	}
 
+	@Override
+	public void setEvaluator(String evaluator) {
+		delegate.setEvaluator(evaluator);
+		onChange();
+	}
+
+	@Override
+	public String getEvaluator() {
+		return delegate.getEvaluator();
+	}
+
 	@Override
 	public void setSchemaVersion(int schemaVersion) {
 		delegate.setSchemaVersion(schemaVersion);
diff --git a/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/HashProblemAndTestCaseData.java b/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/HashProblemAndTestCaseData.java
index 8bef07e7..0844a695 100644
--- a/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/HashProblemAndTestCaseData.java
+++ b/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/HashProblemAndTestCaseData.java
@@ -84,9 +84,11 @@ private void hashProblemData(IProblemData problemData) {
 		updateString(problemData.getLicense().toString());
 		*/
 		
-		// Digest external library URL and MD5 if they are present
+		// Digest external library URL, MD5 and problem evaluator if they are present
 		updateStringIfNonEmpty(problemData.getExternalLibraryUrl());
 		updateStringIfNonEmpty(problemData.getExternalLibraryMD5());
+		
+		updateStringIfNonEmpty(problemData.getEvaluator());
 	}
 
 	private void hashTestCaseData(ITestCaseData testCaseData) {
diff --git a/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/IProblemData.java b/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/IProblemData.java
index 675d06a6..101eab5a 100644
--- a/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/IProblemData.java
+++ b/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/IProblemData.java
@@ -2,6 +2,7 @@
 // Copyright (C) 2011-2013, Jaime Spacco <jspacco@knox.edu>
 // Copyright (C) 2011-2013, David H. Hovemeyer <david.hovemeyer@gmail.com>
 // Copyright (C) 2013, York College of Pennsylvania
+// Copyright (C) 2015, Eisenberger Andras <csirkeee@gmail.com>
 //
 // This program is free software: you can redistribute it and/or modify
 // it under the terms of the GNU Affero General Public License as published by
@@ -68,6 +69,16 @@ public interface IProblemData {
 	 */
 	public abstract String getSkeleton();
 
+	/**
+	 * @param evaluator the evaluator to set
+	 */
+	public abstract void setEvaluator(String evaluator);
+
+	/**
+	 * @return the evaluator, the code used to evaluate tests for a submission
+	 */
+	public abstract String getEvaluator();
+
 	/**
 	 * Set the schema version.
 	 * 
diff --git a/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/Problem.java b/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/Problem.java
index d815bb22..2970fa66 100644
--- a/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/Problem.java
+++ b/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/Problem.java
@@ -219,10 +219,20 @@ public class Problem extends ProblemData implements IProblem, IModelObject<Probl
 	public static final ModelObjectSchema<IProblem> SCHEMA_V11 = ModelObjectSchema.basedOn(SCHEMA_V10)
 		.finishDelta();
 	
+	/**
+	 * Description of fields (schema version 12).
+	 * This version incorporates schema changes from version 8
+	 * of {@link IProblemData}'s schema.
+	 */
+	public static final ModelObjectSchema<IProblem> SCHEMA_V12 =
+			ModelObjectSchema.basedOn(SCHEMA_V11)
+			.addDeltasFrom(ProblemData.SCHEMA_V8)
+			.finishDelta();
+	
 	/**
 	 * Description of fields (current schema version).
 	 */
-	public static final ModelObjectSchema<IProblem> SCHEMA = SCHEMA_V11;
+	public static final ModelObjectSchema<IProblem> SCHEMA = SCHEMA_V12;
 	
 	/**
 	 * Number of fields.
diff --git a/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/ProblemData.java b/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/ProblemData.java
index d50d8810..b0c0a3b0 100644
--- a/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/ProblemData.java
+++ b/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/ProblemData.java
@@ -50,6 +50,7 @@ public class ProblemData implements Serializable, IProblemData {
 	private String parentHash;
 	private String externalLibraryUrl;
 	private String externalLibraryMD5;
+	private String evaluator;
 
 	// Schema version 0 fields
 	
@@ -156,6 +157,14 @@ public class ProblemData implements Serializable, IProblemData {
 		public String get(IProblemData obj) { return obj.getExternalLibraryMD5(); }
 	};
 	
+	// Schema version 8 fields
+
+	public static final ModelObjectField<IProblemData, String> EVALUATOR =
+			new ModelObjectField<IProblemData, String>("evaluator", String.class, 2000, ModelObjectIndexType.NONE, ModelObjectField.LITERAL) {
+		public void set(IProblemData obj, String value) { obj.setEvaluator(value); }
+		public String get(IProblemData obj) { return obj.getEvaluator(); }
+	};
+	
 	/**
 	 * Description of fields (version 0 schema).
 	 */
@@ -228,11 +237,18 @@ public class ProblemData implements Serializable, IProblemData {
 	 */
 	public static final ModelObjectSchema<IProblemData> SCHEMA_V7 = ModelObjectSchema.basedOn(SCHEMA_V6)
 		.finishDelta();
+	
+	/**
+	 * Description of fields (schema version 8).
+	 */
+	public static final ModelObjectSchema<IProblemData> SCHEMA_V8 = ModelObjectSchema.basedOn(SCHEMA_V7)
+		.addAfter(EXTERNAL_LIBRARY_MD5, EVALUATOR)
+		.finishDelta();
 
 	/**
 	 * Description of fields (current schema).
 	 */
-	public static final ModelObjectSchema<IProblemData> SCHEMA = SCHEMA_V7;
+	public static final ModelObjectSchema<IProblemData> SCHEMA = SCHEMA_V8;
 
 	/**
 	 * Constructor.
@@ -338,6 +354,22 @@ public boolean hasSkeleton() {
 		return skeleton != null;
 	}
 
+	/* (non-Javadoc)
+	 * @see org.cloudcoder.app.shared.model.ProblemData#setEvaluator(java.lang.String)
+	 */
+	@Override
+	public void setEvaluator(String evaluator) {
+		this.evaluator = evaluator;
+	}
+
+	/* (non-Javadoc)
+	 * @see org.cloudcoder.app.shared.model.ProblemData#getEvaluator()
+	 */
+	@Override
+	public String getEvaluator() {
+		return evaluator;
+	}
+
 	/* (non-Javadoc)
 	 * @see org.cloudcoder.app.shared.model.ProblemData#setSchemaVersion(int)
 	 */
@@ -484,6 +516,7 @@ public void copyFrom(ProblemData other) {
 		this.parentHash = other.parentHash;
 		this.externalLibraryUrl = other.externalLibraryUrl;
 		this.externalLibraryMD5 = other.externalLibraryMD5;
+		this.evaluator = other.evaluator;
 	}
 	
 	@Override
@@ -505,7 +538,8 @@ public boolean equals(Object obj) {
 				&& ModelObjectUtil.equals(this.license, other.license)
 				&& ModelObjectUtil.equals(this.parentHash, other.parentHash)
 				&& ModelObjectUtil.equals(this.externalLibraryUrl, other.externalLibraryUrl)
-				&& ModelObjectUtil.equals(this.externalLibraryMD5, other.externalLibraryMD5);
+				&& ModelObjectUtil.equals(this.externalLibraryMD5, other.externalLibraryMD5)
+				&& ModelObjectUtil.equals(this.evaluator, other.evaluator);
 	}
 
 	/*
@@ -527,5 +561,6 @@ public static void initEmpty(ProblemData empty) {
 		empty.setTimestampUtc(System.currentTimeMillis());
 		empty.setLicense(ProblemLicense.NOT_REDISTRIBUTABLE);
 		empty.setParentHash("");
+		empty.setEvaluator("");
 	}
 }
\ No newline at end of file
diff --git a/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/RepoProblem.java b/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/RepoProblem.java
index 5009beb4..edfceee1 100644
--- a/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/RepoProblem.java
+++ b/CloudCoderModelClasses/src/org/cloudcoder/app/shared/model/RepoProblem.java
@@ -127,10 +127,20 @@ public class RepoProblem extends ProblemData implements IModelObject<RepoProblem
 	public static final ModelObjectSchema<RepoProblem> SCHEMA_V7 = ModelObjectSchema.basedOn(SCHEMA_V6)
 		.finishDelta();
 	
+	/**
+	 * Description of fields (schema version 8).
+	 * This version incorporates schema changes from version 8
+	 * of {@link IProblemData}'s schema.
+	 */
+	public static final ModelObjectSchema<RepoProblem> SCHEMA_V8 =
+			ModelObjectSchema.basedOn(SCHEMA_V7)
+			.addDeltasFrom(ProblemData.SCHEMA_V8)
+			.finishDelta();
+	
 	/**
 	 * Description of fields (current schema version).
 	 */
-	public static final ModelObjectSchema<RepoProblem> SCHEMA = SCHEMA_V7;
+	public static final ModelObjectSchema<RepoProblem> SCHEMA = SCHEMA_V8;
 	
 	/** Number of fields. */
 	public static final int NUM_FIELDS = SCHEMA.getNumFields();
diff --git a/CloudCoderModelClasses/src/org/cloudcoder/app/shared/util/EvaluatorUtil.java b/CloudCoderModelClasses/src/org/cloudcoder/app/shared/util/EvaluatorUtil.java
new file mode 100644
index 00000000..5dc4581d
--- /dev/null
+++ b/CloudCoderModelClasses/src/org/cloudcoder/app/shared/util/EvaluatorUtil.java
@@ -0,0 +1,65 @@
+// CloudCoder - a web-based pedagogical programming environment
+// Copyright (C) 2015, Andras Eisenberger 
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package org.cloudcoder.app.shared.util;
+
+import org.cloudcoder.app.shared.model.IProblem;
+import org.cloudcoder.app.shared.model.ProblemType;
+
+/**
+ * Utility methods problem evaluators
+ * 
+ * @author Andras Eisenberger
+ */
+public class EvaluatorUtil {
+	/**
+	 * Determine whether custom evaluators can be used for {@link ProblemType}.
+	 * 
+	 * @param problemType the problem type
+	 * @return the AceEditorMode for the Language, or null if the Language is not known
+	 */
+	public static boolean isEvaluatorUsedForProblemType(ProblemType problemType) {
+		switch (problemType) {
+		case PYTHON_FUNCTION:
+			return true;
+		default:
+			return false;
+		}
+	}
+	
+	/**
+	 * Generate the default evaluator for the given problem. Returns empty
+	 * {@link String} for problem types which don't use custom evaluators. 
+	 */
+	public static String getDefaultEvaluator(IProblem problem) {
+		switch (problem.getProblemType()) {
+		case PYTHON_FUNCTION:
+			return getDefaultPythonFunctionEvaluator(problem);
+		default:
+			return "";
+		}
+	}
+	
+	/**
+	 * Generate the default evaluator for a python problem
+	 */
+	public static String getDefaultPythonFunctionEvaluator(IProblem problem) {
+		return "def _eval(_input, _expected):\n" +
+		       "  _output=" + problem.getTestname() + "(*_input)\n" +
+		       "  _result=(_expected == _output) if (type(_output) != float and type(_expected) != float) else (math.fabs(_output-_expected) < 0.00001)\n" +
+		       "  return (_result, _output)\n";
+	}
+}
diff --git a/CloudCoderModelClassesPersistence/src/org/cloudcoder/app/server/persist/CreateSampleData.java b/CloudCoderModelClassesPersistence/src/org/cloudcoder/app/server/persist/CreateSampleData.java
index 9b931582..014a711c 100644
--- a/CloudCoderModelClassesPersistence/src/org/cloudcoder/app/server/persist/CreateSampleData.java
+++ b/CloudCoderModelClassesPersistence/src/org/cloudcoder/app/server/persist/CreateSampleData.java
@@ -105,6 +105,7 @@ public static void populateSampleProblemData(IProblemData problemData) {
 		problemData.setParentHash("");
 		problemData.setExternalLibraryUrl("");
 		problemData.setExternalLibraryMD5("");
+		problemData.setEvaluator("");
 	}
 	
 	public static void populateSampleCFunctionProblem(IProblem problem, int courseId) {
@@ -140,6 +141,7 @@ private static void populateSampleCFunctionProblemData(IProblemData problemData)
 		problemData.setParentHash("");
 		problemData.setExternalLibraryUrl("");
 		problemData.setExternalLibraryMD5("");
+		problemData.setEvaluator("");
 	}
 	
 	public static void populateSampleCFunctionTestCases(ITestCase[] testCases, int problemId) {
diff --git a/default.deps b/default.deps
index 3b779d6f..0a82d47e 100644
--- a/default.deps
+++ b/default.deps
@@ -21,8 +21,8 @@ http://repo1.maven.org/maven2/commons-io/commons-io/2.1/commons-io-2.1.jar
   CloudCoderLoadTester/lib/commons-io-2.1.jar
   CloudCoderLogging/lib/commons-io-2.1.jar
   CloudCoderAnalysis/lib/commons-io-2.1.jar
-http://repo1.maven.org/maven2/org/python/jython-standalone/2.5.3/jython-standalone-2.5.3.jar
-  CloudCoderBuilder2/lib/jython-standalone-2.5.3.jar
+http://repo1.maven.org/maven2/org/python/jython-standalone/2.7.0/jython-standalone-2.7.0.jar
+  CloudCoderBuilder2/lib/jython-standalone-2.7.0.jar
 https://s3.amazonaws.com/org.cloudcoder.daemon.binaries/daemon-${daemon_version}.jar
   CloudCoderJetty/lib/daemon/daemon-${daemon_version}.jar
   CloudCoderBuilder2/lib/daemon-${daemon_version}.jar