Symbols are not variables, but a type of literal value, like numerals and quoted strings. Significantly, symbols are used to represent variables and other named values in the Ruby runtime. So when the Ruby interpreter sees the name foo used as a variable or method name, what it looks up in the Hash of runtime … Read more
From my perspective as sitting with 4 million lines of C++ code (and that’s just one project) from a maintenance perspective I would say: It’s ok to not use getters/setters if members are immutable (i.e. const) or simple with no dependencies (like a point class with members X and Y). If member is private only … Read more
In 0.15.0 you will be able to use the new .dt accessor to do this nice syntactically. In [36]: df = DataFrame(date_range(‘20000101′,periods=150000,freq=’H’),columns=[‘Date’]) In [37]: df.head(5) Out[37]: Date 0 2000-01-01 00:00:00 1 2000-01-01 01:00:00 2 2000-01-01 02:00:00 3 2000-01-01 03:00:00 4 2000-01-01 04:00:00 [5 rows x 1 columns] In [38]: %timeit f(df) 10 loops, best of … Read more
Without the self. notation, the instance variable is modified directly. With it, the property setter is called (and since you made it a retain property, the new pointer that it’s being set to will be sent a retain message). See Apple’s documentation on declaring and accessing properties.
foreach is a read only iterator that iterates dynamically classes that implement IEnumerable, each cycle in foreach will call the IEnumerable to get the next item, the item you have is a read only reference, you can not re-assign it, but simply calling item.Value is accessing it and assigning some value to a read/write attribute … Read more
Let’s go over the basics: “Accessor” and “Mutator” are just fancy names fot a getter and a setter. A getter, “Accessor”, returns a class’s variable or its value. A setter, “Mutator”, sets a class variable pointer or its value. So first you need to set up a class with some variables to get/set: public class … Read more
What you should do: Add a constructor to your super class: public Superclass { public SuperClass(String flavour) { // super class constructor this.flavour = flavour; } } In the Crisps class: public Crisps(String flavour, int quantity) { super(flavour); // send flavour to the super class constructor this.quantity = quantity; } Comments Some comments to … Read more
Here is a small trick that I use in JAVA to replicate C++ friend mechanism. Lets say I have a class Romeo and another class Juliet. They are in different packages (family) for hatred reasons. Romeo wants to cuddle Juliet and Juliet wants to only let Romeo cuddle her. In C++, Juliet would declare Romeo … Read more
There is also the point of view that most of the time, using setters still breaks encapsulation by allowing you to set values that are meaningless. As a very obvious example, if you have a score counter on the game that only ever goes up, instead of // Game private int score; public void setScore(int … Read more