>>> def f(): … return {‘a’ : 1, ‘b’ : 2} … >>> def g(): … return dict(a=1, b=2) … >>> g() {‘a’: 1, ‘b’: 2} >>> f() {‘a’: 1, ‘b’: 2} >>> import dis >>> dis.dis(f) 2 0 BUILD_MAP 0 3 DUP_TOP 4 LOAD_CONST 1 (‘a’) 7 LOAD_CONST 2 (1) 10 ROT_THREE 11 STORE_SUBSCR … Read more
They are equivalent. If you are not coding by any code convention, use which you like better. Personally, I like to leave it out, as it is really just clutter to me.
You can circumvent __init__ by calling __new__ directly. Then you can create a object of the given type and call an alternative method for __init__. This is something that pickle would do. However, first I’d like to stress very much that it is something that you shouldn’t do and whatever you’re trying to achieve, there … Read more
obj = type(‘obj’, (object,), {‘propertyName’ : ‘propertyValue’}) there are two kinds of type function uses.
This seems to explain it well: Instance initializers are a useful alternative to instance variable initializers whenever: initializer code must catch exceptions, or perform fancy calculations that can’t be expressed with an instance variable initializer. You could, of course, always write such code in constructors. But in a class that had multiple constructors, you would … Read more
klass = Object.const_get “ClassName” about class methods class KlassExample def self.klass_method puts “Hello World from Class method” end end klass = Object.const_get “KlassExample” klass.klass_method irb(main):061:0> klass.klass_method Hello World from Class method
You can’t use references here, since as soon as you’d get out of the scope, the reference would point to a object that would be deleted. Really, you have two choices here: 1- Go with pointers: Animal* a; if( happyDay() ) a = new Animal( “puppies” ); //constructor call else a = new Animal( “toads” … Read more
The Java API documentation explains why (http://java.sun.com/javase/6/docs/api/java/lang/Class.html#newInstance()): Note that this method propagates any exception thrown by the nullary constructor, including a checked exception. Use of this method effectively bypasses the compile-time exception checking that would otherwise be performed by the compiler. The Constructor.newInstance method avoids this problem by wrapping any exception thrown by the constructor … Read more
: base(…) If you omit the call to a base constructor it will call the default base constructor automatically. It is mandatory to call a base constructor explicitly if there is no default constructor. Even if there is a default constructor you may still wish to call a different constructor than the default constructor. In … Read more
I originally posted this answer here, but here is a reprint since this isn’t the exact same question but has the same answer: FormatterServices.GetUninitializedObject() will create an instance without calling a constructor. I found this class by using Reflector and digging through some of the core .Net serialization classes. I tested it using the sample … Read more