I am trying to instrument constructors to print out something when they are called. I do this by using insertAfter. I also wanted to print out the object reference. I tried using $_ but that was just set to 0. Is printing out the object reference of the newly newed object possible?
I ended finding a solution to what i wanted. It consisted of using an ExprEditor like this:
public CtClass instrumentMethods() throws CannotCompileException, IOException {
ClassPool cp = ClassPool.getDefault();
cp.insertClassPath(new LoaderClassPath(loader));
CtClass ctKlazz = cp.makeClass(instream);
CtMethod[] methods = ctKlazz.getMethods();
for (CtMethod method : methods) {
final CtBehavior method = methods[ind];
method.instrument(
new ExprEditor() {
// Instrument new expressions:
public void edit(NewExpr expr) throws CannotCompileException {
final int allocSiteId = getAllocSiteId(className, expr.indexOfBytecode());
expr.replace( "{ $_ = $proceed($$); someCodeHere($_); }");
}
}
);
method.insertBefore("{ someInstrumentationAtStart(); }");
}
return ctKlazz;
}
Related
I have created below JUnit5 parameterized test with ArgumentsSource for loading arguments for the test:
public class DemoModelValidationTest {
public ParamsProvider paramsProvider;
public DemoModelValidationTest () {
try {
paramsProvider = new ParamsProvider();
}
catch (Exception iaex) {
}
}
#ParameterizedTest
#ArgumentsSource(ParamsProvider.class)
void testAllConfigurations(int configIndex, String a) throws Exception {
paramsProvider.executeSimulation(configIndex);
}
}
and the ParamsProvider class looks like below:
public class ParamsProvider implements ArgumentsProvider {
public static final String modelPath = System.getProperty("user.dir") + File.separator + "demoModels";
YAMLDeserializer deserializedYAML;
MetaModelToValidationModel converter;
ValidationRunner runner;
List<Configuration> configurationList;
List<Arguments> listOfArguments;
public ParamsProvider() throws Exception {
configurationList = new ArrayList<>();
listOfArguments = new LinkedList<>();
deserializedYAML = new YAMLDeserializer(modelPath);
deserializedYAML.load();
converter = new MetaModelToValidationModel(deserializedYAML);
runner = converter.convert();
configurationList = runner.getConfigurations();
for (int i = 0; i < configurationList.size(); i++) {
listOfArguments.add(Arguments.of(i, configurationList.get(i).getName()));
}
}
public void executeSimulation(int configListIndex) throws Exception {
final Configuration config = runner.getConfigurations().get(configListIndex);
runner.run(config);
runner.getReporter().consolePrintReport();
}
#Override
public Stream<? extends Arguments> provideArguments(ExtensionContext context) {
return listOfArguments.stream().map(Arguments::of);
// return Stream.of(Arguments.of(0, "Actuator Power"), Arguments.of(1, "Error Logging"));
}}
In the provideArguments() method, the commented out code is working fine, but the first line of code
listOfArguments.stream().map(Arguments::of)
is returning the following error:
org.junit.platform.commons.PreconditionViolationException: Configuration error: You must configure at least one set of arguments for this #ParameterizedTest
I am not sure whether I am having a casting problem for the stream in provideArguments() method, but I guess it somehow cannot map the elements of listOfArguments to the stream, which can finally take the form like below:
Stream.of(Arguments.of(0, "Actuator Power"), Arguments.of(1, "Error Logging"))
Am I missing a proper stream mapping of listOfArguments?
provideArguments(…) is called before your test is invoked.
Your ParamsProvider class is instantiated by JUnit. Whatever you’re doing in desiralizeAndCreateValidationRunnerInstance should be done in the ParamsProvider constructor.
Also you’re already wrapping the values fro deserialised configurations to Arguments and you’re double wrapping them in providesArguments.
Do this:
#Override
public Stream<? extends Arguments> provideArguments(ExtensionContext context) {
return listOfArguments.stream();
}}
I want to use javassist (version 3.19-GA) to generate bytecode of a static initializer of a class that starts a thread. For some reason I cannot understand javassist expects a ";" somewhere even though I believe the code I provide is syntactically correct. Does someone see more than I do? Here is the code. What is the problem?
ClassPool pool = ClassPool.getDefault();
final CtClass clazz = pool.get(somename);
clazz.makeClassInitializer().insertAfter(
"try{Runnable r=new Runnable () {public void run () { System.out.println (\"hello!!!!\"); }}; " +
"new Thread(r).start(); } catch(Exception e){}");
I'm getting the following exception:
javassist.CannotCompileException: [source error] ; is missing
at javassist.CtBehavior.insertAfter(CtBehavior.java:877)
at javassist.CtBehavior.insertAfter(CtBehavior.java:792)
at my.code(myclass.java:111)
Thanks for any hint.
Most probably javassist compiler does not support anonymous inner classes like new Runnable () {...}
You have to create new class, inherit it from Runnable, implement method run and create object of this class in your constructor.
package hello;
import javassist.*;
class Test{
}
class Main {
public static void main(String[] args) throws Exception {
ClassPool pool = ClassPool.getDefault();
final CtClass clazz = pool.get(Test.class.getCanonicalName());
CtClass runnable = pool.makeClass("my.custom.RunnableImpl");
runnable.addInterface(pool.get("java.lang.Runnable"));
CtMethod method = CtNewMethod.make("public void run() { System.out.println(\"hello!!!!\"); }", runnable);
runnable.addMethod(method);
// load class
runnable.toClass();
clazz.setName("newTest");
CtConstructor ctConstructor = clazz.makeClassInitializer();
ctConstructor.insertAfter("try{ new Thread( new my.custom.RunnableImpl() ).start(); } catch(Exception e){}");
Class aClass = clazz.toClass();
// call initializer
Class.forName(aClass.getCanonicalName());
Thread.sleep(1000);
}
}
From the official documentation of void insertAfter(String src):
Parameters:
src - the source code representing the inserted bytecode. It must be a
single statement or block.
In your src String parameter, you don't provide a single statement or a block.
A block is "{}".
Try insertBefore(String src) method with global enclosing "{}":
ClassPool pool = ClassPool.getDefault();
final CtClass clazz = pool.get(somename);
clazz.makeClassInitializer().insertBefore(
"{try{Runnable r = new Runnable () {public void run () { System.out.println (\"hello!!!!\"); }}; " +
"new Thread(r).start(); } catch(Exception e){}}");
Considering this IronPython script
def SensorEvent(d):
print d
print d.Message
... how do I access properties of d?
First line of the SensorEvent method successfully prints
{ Message = blah blubb }
however second line throws an exception:
'<>f_anonymousType[str]' object has no attribute 'Message'
Explanation
d is an instance of an anonymous type provided by an invoke from a C# method. I'm invoking it like this:
public static async void ExecutePyFunc(string name, dynamic data)
{
try
{
var f = strategyScope.GetVariable<Action<object>>(name);
if (f != null)
{
await Task.Run(() => f((object)data));
}
}
catch (Exception x)
{
StaticLog("[Callback Exception] Fehler beim Ausführen einer Python Funktion: {0}", x.Message);
}
}
d is a dictionary. Access it like so:
d['Message']
My solution using DynamicObject: I've introduced a class that converts an anonymous type into a known type by copying its properties via reflection (I don't need anything but the properties but it could probably be enhanced for use with fields, methods, functions as well).
Here's what I've come up with:
public class IronPythonKnownType : DynamicObject
{
public IronPythonKnownType(dynamic obj)
{
var properties = obj.GetType().GetProperties();
foreach (PropertyInfo prop in properties)
{
var val = prop.GetValue(obj);
this.Set(prop.Name, val);
}
}
private Dictionary<string, object> _dict = new Dictionary<string, object>();
public override bool TryGetMember(GetMemberBinder binder, out object result)
{
if (_dict.ContainsKey(binder.Name))
{
result = _dict[binder.Name];
return true;
}
return base.TryGetMember(binder, out result);
}
private void Set(string name, object value)
{
_dict[name] = value;
}
public override bool TrySetMember(SetMemberBinder binder, object value)
{
_dict[binder.Name] = value;
return true;
}
}
which effectively converts the anonymous object into something IronPython can handle.
Now I can do that:
def Blubb(a):
print a.Message
without getting the mentioned exception.
I'm using a HeaderColumnNameMappingStrategy to map a csv file with a header into a JavaBean. String values parse fine but any "true" or "false" value in csv doesn't map to JavaBean and I get the following exception from the PropertyDescriptor:
java.lang.IllegalArgumentException: argument type mismatch
The code where it occurs is in CsvToBean, line 64:
protected T processLine(MappingStrategy<T> mapper, String[] line) throws
IllegalAccessException, InvocationTargetException, InstantiationException, IntrospectionException {
T bean = mapper.createBean();
for(int col = 0; col < line.length; col++) {
String value = line[col];
PropertyDescriptor prop = mapper.findDescriptor(col);
if (null != prop) {
Object obj = convertValue(value, prop);
// this is where exception is thrown for a "true" value in csv
prop.getWriteMethod().invoke(bean, new Object[] {obj});
}
}
return bean;
}
protected PropertyEditor getPropertyEditor(PropertyDescriptor desc) throws
InstantiationException, IllegalAccessException {
Class<?> cls = desc.getPropertyEditorClass();
if (null != cls) return (PropertyEditor) cls.newInstance();
return getPropertyEditorValue(desc.getPropertyType());
}
I can confirm (via debugger) that the setter method id correctly retrieved at this point.
The problem occurs in desc.getPropertyEditorClass() since it returns null. I assumed primitive types and its wrappers are supported. Are they not?
I've run into this same issue. The cleanest way is probably to override getPropertyEditor like pritam did above and return a custom PropertyEditor for your particular object. The quick and dirty way would be to override convertValue in anonymous class form, like this:
CsvToBean<MyClass> csvToBean = new CsvToBean<MyClass>(){
#Override
protected Object convertValue(String value, PropertyDescriptor prop) throws InstantiationException,IllegalAccessException {
if (prop.getName().equals("myWhatever")) {
// return an custom object based on the incoming value
return new MyWhatever((String)value);
}
return super.convertValue(value, prop);
}
};
This is working fine for me with OpenCSV 2.3. Good luck!
I resolved this by extending CsvToBean and adding my own PropertyEditors. Turns out opencsv just supports primitive types and no wrappers.
Pritam's answer is great and this is a sample for dealing with datetime format.
PropertyEditorManager.registerEditor(java.util.Date.class, DateEditor.class);
You should write your own editor class like this:
public class DateEditor extends PropertyEditorSupport{
public static final SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
#Override
public void setAsText(String text){
setValue(sdf.parse(text));}
}
I'm wanting to have a simple duck typing example in C# using dynamic objects. It would seem to me, that a dynamic object should have HasValue/HasProperty/HasMethod methods with a single string parameter for the name of the value, property, or method you are looking for before trying to run against it. I'm trying to avoid try/catch blocks, and deeper reflection if possible. It just seems to be a common practice for duck typing in dynamic languages (JS, Ruby, Python etc.) that is to test for a property/method before trying to use it, then falling back to a default, or throwing a controlled exception. The example below is basically what I want to accomplish.
If the methods described above don't exist, does anyone have premade extension methods for dynamic that will do this?
Example: In JavaScript I can test for a method on an object fairly easily.
//JavaScript
function quack(duck) {
if (duck && typeof duck.quack === "function") {
return duck.quack();
}
return null; //nothing to return, not a duck
}
How would I do the same in C#?
//C# 4
dynamic Quack(dynamic duck)
{
//how do I test that the duck is not null,
//and has a quack method?
//if it doesn't quack, return null
}
If you have control over all of the object types that you will be using dynamically, another option would be to force them to inherit from a subclass of the DynamicObject class that is tailored to not fail when a method that does not exist is invoked:
A quick and dirty version would look like this:
public class DynamicAnimal : DynamicObject
{
public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result)
{
bool success = base.TryInvokeMember(binder, args, out result);
// If the method didn't exist, ensure the result is null
if (!success) result = null;
// Always return true to avoid Exceptions being raised
return true;
}
}
You could then do the following:
public class Duck : DynamicAnimal
{
public string Quack()
{
return "QUACK!";
}
}
public class Cow : DynamicAnimal
{
public string Moo()
{
return "Mooooo!";
}
}
class Program
{
static void Main(string[] args)
{
var duck = new Duck();
var cow = new Cow();
Console.WriteLine("Can a duck quack?");
Console.WriteLine(DoQuack(duck));
Console.WriteLine("Can a cow quack?");
Console.WriteLine(DoQuack(cow));
Console.ReadKey();
}
public static string DoQuack(dynamic animal)
{
string result = animal.Quack();
return result ?? "... silence ...";
}
}
And your output would be:
Can a duck quack?
QUACK!
Can a cow quack?
... silence ...
Edit: I should note that this is the tip of the iceberg if you are able to use this approach and build on DynamicObject. You could write methods like bool HasMember(string memberName) if you so desired.
Try this:
using System.Linq;
using System.Reflection;
//...
public dynamic Quack(dynamic duck, int i)
{
Object obj = duck as Object;
if (duck != null)
{
//check if object has method Quack()
MethodInfo method = obj.GetType().GetMethods().
FirstOrDefault(x => x.Name == "Quack");
//if yes
if (method != null)
{
//invoke and return value
return method.Invoke((object)duck, null);
}
}
return null;
}
Or this (uses only dynamic):
public static dynamic Quack(dynamic duck)
{
try
{
//invoke and return value
return duck.Quack();
}
//thrown if method call failed
catch (RuntimeBinderException)
{
return null;
}
}
Implementation of the HasProperty method for every IDynamicMetaObjectProvider WITHOUT throwing RuntimeBinderException.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Dynamic;
using Microsoft.CSharp.RuntimeBinder;
using System.Linq.Expressions;
using System.Runtime.CompilerServices;
namespace DynamicCheckPropertyExistence
{
class Program
{
static void Main(string[] args)
{
dynamic testDynamicObject = new ExpandoObject();
testDynamicObject.Name = "Testovaci vlastnost";
Console.WriteLine(HasProperty(testDynamicObject, "Name"));
Console.WriteLine(HasProperty(testDynamicObject, "Id"));
Console.ReadLine();
}
private static bool HasProperty(IDynamicMetaObjectProvider dynamicProvider, string name)
{
var defaultBinder = Binder.GetMember(CSharpBinderFlags.None, name, typeof(Program),
new[]
{
CSharpArgumentInfo.Create(
CSharpArgumentInfoFlags.None, null)
}) as GetMemberBinder;
var callSite = CallSite<Func<CallSite, object, object>>.Create(new NoThrowGetBinderMember(name, false, defaultBinder));
var result = callSite.Target(callSite, dynamicProvider);
if (Object.ReferenceEquals(result, NoThrowExpressionVisitor.DUMMY_RESULT))
{
return false;
}
return true;
}
}
class NoThrowGetBinderMember : GetMemberBinder
{
private GetMemberBinder m_innerBinder;
public NoThrowGetBinderMember(string name, bool ignoreCase, GetMemberBinder innerBinder) : base(name, ignoreCase)
{
m_innerBinder = innerBinder;
}
public override DynamicMetaObject FallbackGetMember(DynamicMetaObject target, DynamicMetaObject errorSuggestion)
{
var retMetaObject = m_innerBinder.Bind(target, new DynamicMetaObject[] {});
var noThrowVisitor = new NoThrowExpressionVisitor();
var resultExpression = noThrowVisitor.Visit(retMetaObject.Expression);
var finalMetaObject = new DynamicMetaObject(resultExpression, retMetaObject.Restrictions);
return finalMetaObject;
}
}
class NoThrowExpressionVisitor : ExpressionVisitor
{
public static readonly object DUMMY_RESULT = new DummyBindingResult();
public NoThrowExpressionVisitor()
{
}
protected override Expression VisitConditional(ConditionalExpression node)
{
if (node.IfFalse.NodeType != ExpressionType.Throw)
{
return base.VisitConditional(node);
}
Expression<Func<Object>> dummyFalseResult = () => DUMMY_RESULT;
var invokeDummyFalseResult = Expression.Invoke(dummyFalseResult, null);
return Expression.Condition(node.Test, node.IfTrue, invokeDummyFalseResult);
}
private class DummyBindingResult {}
}
}
impromptu-interface seems to be a nice Interface mapper for dynamic objects... It's a bit more work than I was hoping for, but seems to be the cleanest implementation of the examples presented... Keeping Simon's answer as correct, since it is still the closest to what I wanted, but the Impromptu interface methods are really nice.
The shortest path would be to invoke it, and handle the exception if the method does not exist. I come from Python where such method is common in duck-typing, but I don't know if it is widely used in C#4...
I haven't tested myself since I don't have VC 2010 on my machine
dynamic Quack(dynamic duck)
{
try
{
return duck.Quack();
}
catch (RuntimeBinderException)
{ return null; }
}
Have not see a correct answer here, MS provides an example now with casting to a dictionary
dynamic employee = new ExpandoObject();
employee.Name = "John Smith";
employee.Age = 33;
foreach (var property in (IDictionary<String, Object>)employee)
{
Console.WriteLine(property.Key + ": " + property.Value);
}
// This code example produces the following output:
// Name: John Smith
// Age: 33