Strings in Ruby Are Mutable
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
18-Variables.Pdf
Mehran Sahami Handout #18 CS 106A October 12, 2007 Variables, variables, everywhere… Based on a handout by Patrick Young. Local Variables Local variables are created local to the method (or the block—see “Block Scope” section below) in which they are defined. They are destroyed when execution of the method has been completed. Local variables can only be accessed from within the method in which they are declared. Because of their transient nature, local variables cannot store persistent information about an object between method calls. Local Variables Example Consider, for example, the following snippet of code. class AnExample extends ConsoleProgram { public void methodOne { int a = readInt("Enter a: "); println("a = " + a); } public void methodTwo { int b = a; // BUG!: cannot refer to variable a in methodOne println("b = " + b); } } The variables a and b are local variables declared within different methods in the class AnExample . Because these variables are local variables, a can only be referred to within methodOne and variable b can only be accessed within methodTwo . Our attempt to initialize b using the value of a is illegal, as code in methodTwo cannot access local variables from methodOne or any other method. Because local variable values do not persist after their containing method has completed, the variable a will be destroyed when methodOne has completed execution. The next time methodOne is called, a new variable a will be created. Block Scope While we typically think of local variables as local to a particular method, in Java local variables are actually local to a block of code. While a method defines a block of code (since the opening and closing braces of the method define a block), for and while loops, if -statements, and other constructs are also considered blocks of code. -
Java Static Keyword
This page was exported from - TechnicalStack Export date: Sun Sep 26 13:56:23 2021 / +0000 GMT Java static keyword Java static keyword The static keyword in java is used for memory management mainly. We can apply java static keyword with variables, methods, blocks and nested class. The static keyword belongs to the class than instance of the class. The static can be: - variable (also known as class variable) - method (also known as class method) - block - nested class 1) Java static variable If you declare any variable as static, it is known static variable. - The static variable can be used to refer the common property of all objects (that is not unique for each object) e.g. company name of employees,college name of students etc. - The static variable gets memory only once in class area at the time of class loading. Advantage of static variable It makes your program memory efficient (i.e it saves memory). Understanding problem without static variable class Student{ int rollno; String name; String college="ITS"; } Suppose there are 500 students in my college, now all instance data members will get memory each time when object is created.All student have its unique rollno and name so instance data member is good.Here, college refers to the common property of all objects.If we make it static,this field will get memory only once. Java static property is shared to all objects. Example of static variable //Program of static variable class Student8{ int rollno; String name; static String college ="ITS"; Student8(int r,String n){ -
CS 61A A&S Section 3.0 Object-Oriented Programming
CS 61A A&S Section 3.0 Object-Oriented Programming | Above the line view This document should be read before Section 3.1 of the text. A second document, \Object-Oriented Programming | Below the line view," should be read after Section 3.1 and perhaps after Section 3.2; the idea is that you first learn how to use the object-oriented programming facility, then you learn how it's implemented. Object-oriented programming is a metaphor. It expresses the idea of several independent agents inside the computer, instead of a single process manipulating various data. For example, the next programming project is an adventure game, in which several people, places, and things interact. We want to be able to say things like \Ask Fred to pick up the potstickers." (Fred is a person object, and the potstickers are a thing object.) Programmers who use the object metaphor have a special vocabulary to describe the components of an object-oriented programming (OOP) system. In the example just above, \Fred" is called an instance and the general category \person" is called a class. Programming languages that support OOP let the programmer talk directly in this vocabulary; for example, every OOP language has a “define class" command in some form. For this course, we have provided an extension to Scheme that supports OOP in the style of other OOP languages. Later we shall see how these new features are implemented using Scheme capabilities that you already understand. OOP is not magic; it's a way of thinking and speaking about the structure of a program. -
Rubabel: Wrapping Open Babel with Ruby Rob Smith1*, Ryan Williamson1, Dan Ventura1 and John T Prince2*
Smith et al. Journal of Cheminformatics 2013, 5:35 http://www.jcheminf.com/content/5/1/35 SOFTWARE Open Access Rubabel: wrapping open Babel with Ruby Rob Smith1*, Ryan Williamson1, Dan Ventura1 and John T Prince2* Abstract Background: The number and diversity of wrappers for chemoinformatic toolkits suggests the diverse needs of the chemoinformatic community. While existing chemoinformatics libraries provide a broad range of utilities, many chemoinformaticians find compiled language libraries intimidating, time-consuming, arcane, and verbose. Although high-level language wrappers have been implemented, more can be done to leverage the intuitiveness of object-orientation, the paradigms of high-level languages, and the extensibility of languages such as Ruby. We introduce Rubabel, an intuitive, object-oriented suite of functionality that substantially increases the accessibily of the tools in the Open Babel chemoinformatics library. Results: Rubabel requires fewer lines of code than any other actively developed wrapper, providing better object organization and navigation, and more intuitive object behavior than extant solutions. Moreover, Rubabel provides a convenient interface to the many extensions currently available in Ruby, greatly streamlining otherwise onerous tasks such as creating web applications that serve up Rubabel functionality. Conclusions: Rubabel is powerful, intuitive, concise, freely available, cross-platform, and easy to install. We expect it to be a platform of choice for new users, Ruby users, and some users of current solutions. Keywords: Chemoinformatics, Open Babel, Ruby Background tasks. Though it allows the user to access the functionality Despite the fact that chemoinformatics tools have been of the component libraries from one Python script, Cin- developed since the late 1990s [1], the field has yet to fony does not automatically manage underlying data types rally in support of a single library. -
10. Classes: an Initial Example
10. Classes: An Initial Example This is the first chapter about classes. It is also the first chapter in the first lecture about classes. Our basic coverage of classes runs until Chapter 13. 10.1. The Die Class Lecture 3 - slide 2 In this section we encounter a number of important OOP ideas, observations, and principles. We will very briefly preview many of these in a concrete way in the context of a simple initial class. Later we will discuss the ideas in depth. We use the example of a die , which is the singular form of "dice", see Program 10.1. One of the teaching assistants in 2006 argued that the class Die is a sad beginning of the story about classes. Well, it is maybe right. I think, however, that the concept of a die is a good initial example. So we will go for it! On purpose, we are concerned with use of either the singular or the plural forms of class names. The singular form is used when we wish to describe and program a single phenomenon/thing/object. The plural form is most often used for collections, to which we can add or delete (singular) objects. Notice that we can make multiple instances of a class, such as the Die class. In this way we can create a number of dice. The class Die in Program 10.1 is programmed in C#. We program a die such that each given die has a fixed maximum number of eyes, determined by the constant maxNumberOfEyes . The class encapsulates the instance variables : numberOfEyes , randomNumberSupplier , and the constant maxNumberOfEyes . -
C++ Fundamentals
C++ Fundamentals Only what you need to know Outline • Part 1 – Basic Syntax Review – C++ Definitions, Source Code Organization, Building your Code • Part 2 – Scope – Pointers and References – Dynamic Memory Allocation – Const-ness – Function Overloading • Part 3 – Type System – Brief Intro to Using Templates – C++ Data Structures – Standard Template Library Containers • Part 4 – Object Oriented Design – Classes in C++ 2 / 82 Typeface Conventions • Key concepts • Special attention required! • Code • // Comments • int x;// Language keywords 3 / 82 MOOSE Coding Standards • Capitalization –ClassName –methodName – member variable – local variable • FileNames – src/ClassName.C – include/ClassName.h • Spacing – Two spaces for each indentation level – Four spaces for initialization lists – Braces should occupy their own line – Spaces around all binary operators and declaration symbols + - * & ... • No Trailing Whitespace! • Documentation for each method (Doxygen keywords) – @param – @return – ///Doxygen Style Comment • See our wiki page for a comprehensive list https://hpcsc.inl.gov/moose/wiki/CodeStandards 4 / 82 Part 1 • Basic Syntax Review • C++ Definitions • Source Code Organization • Building your Code 5 / 82 Review: C Preprocessor Commands • “#” Should be the first character on the line – #include <iostream> – #include "myheader.h" – #define SOMEWORD value – #ifdef, #ifndef, #endif • Some predefined Macros – FILE – LINE – cplusplus 6 / 82 Review: Intrinsic Data Types Basic Type Variant(s) bool char unsigned int unsigned, long, short float double -
Chapter 4 Methods
Chapter 4 Methods Hello! Today we will focus on the static keyword, calling conventions of methods, and what scope and lifetime mean in Java. Now that our chapters will tend to generate multiple files, I strongly suggest you create a folder for each lab, and then just add files to that folder. Naming Things. Quick note on names: when we create a variable in a class – whether we make it static or not – we can refer to it as a field. We may refer to both fields and methods as members of the class. Although we have strived to use the same names for things, these words are commonly used to refer to the variables and methods in a class. Methods – Static Methods The way in Java to name a block of code, and then be able to call it elsewhere, is to write a method. A method always goes in a class definition. We have one major distinction to make, though: should the method be static or not? A static method can be called all by itself (no object of the enclosing class needed), much like a function in Python. A non-static method in Java is written in a class and associated with a particular object and thus can use the object's instance variables. Being non-static is the default behavior in Java, specified by the absence of the static modifier. We focus first in this tutorial on writing static methods. Non-static Method Example Here is an example of a non-static method, in the Square class: look at the perimeter method below. -
Hbase: the Definitive Guide
HBase: The Definitive Guide HBase: The Definitive Guide Lars George Beijing • Cambridge • Farnham • Köln • Sebastopol • Tokyo HBase: The Definitive Guide by Lars George Copyright © 2011 Lars George. All rights reserved. Printed in the United States of America. Published by O’Reilly Media, Inc., 1005 Gravenstein Highway North, Sebastopol, CA 95472. O’Reilly books may be purchased for educational, business, or sales promotional use. Online editions are also available for most titles (http://my.safaribooksonline.com). For more information, contact our corporate/institutional sales department: (800) 998-9938 or [email protected]. Editors: Mike Loukides and Julie Steele Indexer: Angela Howard Production Editor: Jasmine Perez Cover Designer: Karen Montgomery Copyeditor: Audrey Doyle Interior Designer: David Futato Proofreader: Jasmine Perez Illustrator: Robert Romano Printing History: September 2011: First Edition. Nutshell Handbook, the Nutshell Handbook logo, and the O’Reilly logo are registered trademarks of O’Reilly Media, Inc. HBase: The Definitive Guide, the image of a Clydesdale horse, and related trade dress are trademarks of O’Reilly Media, Inc. Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those designations appear in this book, and O’Reilly Media, Inc., was aware of a trademark claim, the designations have been printed in caps or initial caps. While every precaution has been taken in the preparation of this book, the publisher and author assume no responsibility for errors or omissions, or for damages resulting from the use of the information con- tained herein. ISBN: 978-1-449-39610-7 [LSI] 1314323116 For my wife Katja, my daughter Laura, and son Leon. -
Classes & Objects
CLASSES AND OBJECTS Summer 2019 OBJECT BASICS • Everything in Java is part of a class • This includes all methods (functions) • Even the main() method is part of a class • Classes are declared similar to C++ • This includes the ability to categorize members as public or private, but the qualifiers are placed before each individual member • With no access level, a class member is considered package-private (accessible only to other classes in the same package, a concept discussed later) • These two categories have the same meaning as in C++: public means accessible from anywhere, private means only accessible from within the class • Follow the same guidelines as in C++ (member data usually private, member functions at an appropriate level based on access requirements) OBJECT BASICS • Class Declaration, continued • In Java, classes themselves have access levels. • Normal classes are usually declared public, so they can be accessed anywhere • Other access levels are usually reserved for specific types of classes (such as inner classes, discussed later) • Circle.java – class declaration example CREATING OBJECTS • Objects are created from a class using the new operator and they must be attached to a reference variable. This takes two steps: 1. Declare the object reference variable 2. Create the object with new and attach it to the reference variable • This means every object is dynamically created. CREATING OBJECTS • The Format: ClassName objectReference; objectReference = new ClassName(); OR ClassName objectReference = new ClassName(); • Examples: -
Declaring Variables in Class Python
Declaring Variables In Class Python Corky whinings her floorwalkers backstage, desiccated and ecaudate. Unchary Cy leverages falsely and creakily, she taunt her spermatocele vanned soulfully. Sigfrid remains plaintive: she rusticated her exclusivists jutted too respectfully? Global name an error and assign a derived class itself is that points describing the same way as a variable in python variables in class python. If to declare a class named Device and initialize a variable dev to plumbing new. The grab to porter this are nonlocal definitions, should be pleasure in the global namespace. This class contains a single constructor. It is faster and more add to attend the real Python course outside a classroom. Make sure your community account class, this allows multiple pieces of an interface, and how to take in class but the collection, known as spam! PHP because when are less structure than the traditional languages with your fancy features. Each tutorial at Real Python is created by a soft of developers so leaving it meets our incredible quality standards. Object Oriented Programming in Python Stack Abuse. The special function are not create an input data type object oriented programming languages often think of m_value: if we are. Python class Objects and classes Python Tutorial Pythonspot. Objects can be a double underscores when you define what are in order for. Understanding Class and Instance Variables in Python 3. For example also it in which makes up! Instances of a Class Python Like root Mean It. This stage notice provides an overturn of our commitment to privacy and describes how we color, and undo some applications that might achieve a real choice. -
A Uniform Model for Object-Oriented Languages Using the Class Abstraction
A Uniform Model for Object-Oriented Languages Using The Class Abstraction Jean-Pierre BRIOT Pierre COINTE LITP, University Paris-6 Rank Xerox France 4 Place Jussieu 12 Place de l'IRIS Paris, 75005 La Defense, 92071 mcvax!inria!litp!jpb mcvax!inria!litp!pc Abstract Object-oriented programming is built from the class model, introduced in the language Simula-67. In Simula, One of the main goals of object-oriented languages is to a class is a way to describe an abstract data structure. unify their universe: "every entity of the language is an ob• Active objects may be dynamically created from the class ject.* The class concept, however, usually does not follow description by instantiating the variables specified by the this wish: a class being not a real object, i.e., created from class. Such objects are called instances of the class. a class. The metaclass concept introduced in Smalltalk- B. Is a Class an Object? 80, attempts to give classes a first class citizenship but "With respect to Simula, Smalltalk abandons static scoping, to complicates the instantiation scheme without solving its gain flexibility in interactive use, and strong typing, allowing it fundamental limitations: the only partial specification of to implement system introspection and to introduce the notion of the class at the metaclass level, and the fixed number of metaclasses9 [4]. meta-levels. The object paradigm is set, and is now distinct from Some more recent approaches, as in Loops and then abstract data types systems. The Smalltalk language has CommonLoops, tend towards a better unification, but re• evolved from Smalltalk-72 [7] to Smalltalk-80 in order to veal the same limitations. -
Specialising Dynamic Techniques for Implementing the Ruby Programming Language
SPECIALISING DYNAMIC TECHNIQUES FOR IMPLEMENTING THE RUBY PROGRAMMING LANGUAGE A thesis submitted to the University of Manchester for the degree of Doctor of Philosophy in the Faculty of Engineering and Physical Sciences 2015 By Chris Seaton School of Computer Science This published copy of the thesis contains a couple of minor typographical corrections from the version deposited in the University of Manchester Library. [email protected] chrisseaton.com/phd 2 Contents List of Listings7 List of Tables9 List of Figures 11 Abstract 15 Declaration 17 Copyright 19 Acknowledgements 21 1 Introduction 23 1.1 Dynamic Programming Languages.................. 23 1.2 Idiomatic Ruby............................ 25 1.3 Research Questions.......................... 27 1.4 Implementation Work......................... 27 1.5 Contributions............................. 28 1.6 Publications.............................. 29 1.7 Thesis Structure............................ 31 2 Characteristics of Dynamic Languages 35 2.1 Ruby.................................. 35 2.2 Ruby on Rails............................. 36 2.3 Case Study: Idiomatic Ruby..................... 37 2.4 Summary............................... 49 3 3 Implementation of Dynamic Languages 51 3.1 Foundational Techniques....................... 51 3.2 Applied Techniques.......................... 59 3.3 Implementations of Ruby....................... 65 3.4 Parallelism and Concurrency..................... 72 3.5 Summary............................... 73 4 Evaluation Methodology 75 4.1 Evaluation Philosophy