Here’s a little love for class decorators. I think the syntax is slightly simpler than that required for metaclasses. def class_register(cls): cls._propdict = {} for methodname in dir(cls): method = getattr(cls, methodname) if hasattr(method, ‘_prop’): cls._propdict.update( {cls.__name__ + ‘.’ + methodname: method._prop}) return cls def register(*args): def wrapper(func): func._prop = args return func return wrapper … Read more
As per the comment on your question: I’ve a properties file containing some keys value pairs, which is need across the application, that is why I was thinking about a singleton class. This class will load the properties from a file and keep it and you can use it from anywhere in the application Don’t … Read more
The problem is not the ‘if’ statement, it is the programmers who write bad code. EDIT: Also, as others have pointed out, you should be using polymorphism (if available) when you are using if statements to check the type of an object, but if statements in and of themselves are very useful and fundamental constructs.
The Streams in Java – subclasses of InputStream and OutputStream are perfect examples of the decorator pattern. As an example, writing a file to disk: File toWriteTo = new File(“C:\\temp\\tempFile.txt”); OutputStream outputStream = new FileOutputStream(toWriteTo); outputStream.write(“Sample text”.getBytes()); Then should you require some extra functionality regarding the writing to disk: File toWriteTo = new File(“C:\\temp\\tempFile.txt”); OutputStream … Read more
When you construct an object Python calls its __new__ method to create the object then calls __init__ on the object that is returned. When you create the object from inside __new__ by calling Triangle() that will result in further calls to __new__ and __init__. What you should do is: class Shape(object): def __new__(cls, desc): if … Read more
Singleton is ugly but… public class Singleton { private static Singleton _instance = null; private static Object _mutex = new Object(); private Singleton(object arg1, object arg2) { // whatever } public static Singleton GetInstance(object arg1, object arg2) { if (_instance == null) { lock (_mutex) // now I can claim some form of thread safety… … Read more
The traditional builder pattern already handles this: simply take the mandatory parameters in the constructor. Of course, nothing prevents a caller from passing null, but neither does your method. The big problem I see with your method is that you either have a combinatorical explosion of classes with the number of mandatory parameters, or force … Read more
Another popular method is to associate the strings by their Jaccard index. Start with http://en.wikipedia.org/wiki/Jaccard_index. Here’s a article about using the Jaccard-index (and a couple of other methods) to solve a problem like yours: http://matpalm.com/resemblance/
If you’re targeting 1.6 or later, you can use the android:onClick xml attribute to remove some of the repetitive code. See this blog post by Romain Guy. <Button android:height=”wrap_content” android:width=”wrap_content” android:onClick=”myClickHandler” /> And in the Java class, use these below lines of code: class MyActivity extends Activity { public void myClickHandler(View target) { // Do … Read more
I would opt for AutoMapper, an open source and free mapping library which allows to map one type into another, based on conventions (i.e. map public properties with the same names and same/derived/convertible types, along with many other smart ones). Very easy to use, will let you achieve something like this: Model model = Mapper.Map<Model>(dto); … Read more