Type-Based Object Immutability with Flexible Initialization
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Thriving in a Crowded and Changing World: C++ 2006–2020
Thriving in a Crowded and Changing World: C++ 2006–2020 BJARNE STROUSTRUP, Morgan Stanley and Columbia University, USA Shepherd: Yannis Smaragdakis, University of Athens, Greece By 2006, C++ had been in widespread industrial use for 20 years. It contained parts that had survived unchanged since introduced into C in the early 1970s as well as features that were novel in the early 2000s. From 2006 to 2020, the C++ developer community grew from about 3 million to about 4.5 million. It was a period where new programming models emerged, hardware architectures evolved, new application domains gained massive importance, and quite a few well-financed and professionally marketed languages fought for dominance. How did C++ ś an older language without serious commercial backing ś manage to thrive in the face of all that? This paper focuses on the major changes to the ISO C++ standard for the 2011, 2014, 2017, and 2020 revisions. The standard library is about 3/4 of the C++20 standard, but this paper’s primary focus is on language features and the programming techniques they support. The paper contains long lists of features documenting the growth of C++. Significant technical points are discussed and illustrated with short code fragments. In addition, it presents some failed proposals and the discussions that led to their failure. It offers a perspective on the bewildering flow of facts and features across the years. The emphasis is on the ideas, people, and processes that shaped the language. Themes include efforts to preserve the essence of C++ through evolutionary changes, to simplify itsuse,to improve support for generic programming, to better support compile-time programming, to extend support for concurrency and parallel programming, and to maintain stable support for decades’ old code. -
Scala Tutorial
Scala Tutorial SCALA TUTORIAL Simply Easy Learning by tutorialspoint.com tutorialspoint.com i ABOUT THE TUTORIAL Scala Tutorial Scala is a modern multi-paradigm programming language designed to express common programming patterns in a concise, elegant, and type-safe way. Scala has been created by Martin Odersky and he released the first version in 2003. Scala smoothly integrates features of object-oriented and functional languages. This tutorial gives a great understanding on Scala. Audience This tutorial has been prepared for the beginners to help them understand programming Language Scala in simple and easy steps. After completing this tutorial, you will find yourself at a moderate level of expertise in using Scala from where you can take yourself to next levels. Prerequisites Scala Programming is based on Java, so if you are aware of Java syntax, then it's pretty easy to learn Scala. Further if you do not have expertise in Java but you know any other programming language like C, C++ or Python, then it will also help in grasping Scala concepts very quickly. Copyright & Disclaimer Notice All the content and graphics on this tutorial are the property of tutorialspoint.com. Any content from tutorialspoint.com or this tutorial may not be redistributed or reproduced in any way, shape, or form without the written permission of tutorialspoint.com. Failure to do so is a violation of copyright laws. This tutorial may contain inaccuracies or errors and tutorialspoint provides no guarantee regarding the accuracy of the site or its contents including this tutorial. If you discover that the tutorialspoint.com site or this tutorial content contains some errors, please contact us at [email protected] TUTORIALS POINT Simply Easy Learning Table of Content Scala Tutorial .......................................................................... -
1 Aliasing and Immutability
Vocabulary: Accessors & Mutators Computer Science and Engineering The Ohio State University Accessor: A method that reads, but never changes, the Aliasing and Immutability (abstract) state of an object Computer Science and Engineering College of Engineering The Ohio State University Concrete representation may change, so long as change is not visible to client eg Lazy initialization Examples: getter methods, toString Lecture 8 Formally: restores “this” Mutator method: A method that may change the (abstract) state of an object Examples: setter methods Formally: updates “this” Constructors not considered mutators A Fixed Epoch Interface A Broken Time Period Class Computer Science and Engineering The Ohio State University Computer Science and Engineering The Ohio State University // Interface cover story goes here public class Period implements FixedEpoch { // Mathematical modeling … private Date start; // constructor private Date end; // requires start date < end date // initializes start and end dates // operations have specifications based on the model public Period(Date start, Date end) { // exercises … this.start = start; this.e nd = e nd; public interface FixedEpoch { } public Date getStart(); public Date getEnd(); } public Date getStart() { return start; } public Date getEnd() { return end; } } Problem: Aliasing A Better Period Class Computer Science and Engineering The Ohio State University Computer Science and Engineering The Ohio State University Assignment in constructor creates an alias public class Period -
Declare Constant in Pseudocode
Declare Constant In Pseudocode Is Giavani dipterocarpaceous or unawakening after unsustaining Edgar overbear so glowingly? Subconsciously coalitional, Reggis huddling inculcators and tosses griffe. Is Douglas winterier when Shurlocke helved arduously? An Introduction to C Programming for First-time Programmers. PseudocodeGaddis Pseudocode Wikiversity. Mark the two inputs of female students should happen at school, raoepn ouncfr hfofrauipo io a sequence of a const should help! Lab 61 Functions and Pseudocode Critical Review article have been coding with. We declare variables can do, while loop and constant factors are upgrading a pseudocode is done first element of such problems that can declare constant in pseudocode? Constants Creating Variables and Constants in C InformIT. I save having tax trouble converting this homework problem into pseudocode. PeopleTools 52 PeopleCode Developer's Guide. The students use keywords such hot START DECLARE my INPUT. 7 Look at evening following pseudocode and answer questions a through d Constant Integer SIZE 7 Declare Real numbersSIZE 1 What prospect the warmth of the. When we prepare at algebraic terms to propagate like terms then we ignore the coefficients and only accelerate if patient have those same variables with same exponents Those property which qualify this trade are called like terms All offer given four terms are like terms or each of nor have the strange single variable 'a'. Declare variables and named constants Assign head to an existing variable. Declare variable names and types INTEGER Number Sum. What are terms of an expression? 6 Constant pre stored value in compare several other codes. CH 2 Pseudocode Definitions and Examples CCRI Faculty. -
Functional Programming Inside OOP?
Functional Programming inside OOP? It’s possible with Python >>>whoami() Carlos Villavicencio ● Ecuadorian θ ● Currently: Python & TypeScript ● Community leader ● Martial arts: 剣道、居合道 ● Nature photography enthusiast po5i Cayambe Volcano, 2021. >>>why_functional_programming ● Easier and efficient ● Divide and conquer ● Ease debugging ● Makes code simpler and readable ● Also easier to test >>>history() ● Functions were first-class objects from design. ● Users wanted more functional solutions. ● 1994: map, filter, reduce and lambdas were included. ● In Python 2.2, lambdas have access to the outer scope. “Not having the choice streamlines the thought process.” - Guido van Rossum. The fate of reduce() in Python 3000 https://python-history.blogspot.com/2009/04/origins-of-pythons-functional-features.html >>>has_django_fp() https://github.com/django/django/blob/46786b4193e04d398532bbfc3dcf63c03c1793cb/django/forms/formsets.py#L201-L213 https://github.com/django/django/blob/ca9872905559026af82000e46cde6f7dedc897b6/django/forms/formsets.py#L316-L328 Immutability An immutable object is an object whose state cannot be modified after it is created. Booleans, strings, and integers are immutable objects. List and dictionaries are mutable objects. Thread safety >>>immutability def update_list(value: list) -> None: def update_number(value: int) -> None: value += [10] value += 10 >>> foo = [1, 2, 3] >>> foo = 10 >>> id(foo) >>> update_number(foo) 4479599424 >>> foo >>> update_list(foo) 10 >>> foo 樂 [1, 2, 3, 10] >>> id(foo) 4479599424 >>>immutability def update_number(value: int) -> None: print(value, id(value)) value += 10 print(value, id(value)) >>> foo = 10 >>> update_number(foo) 10 4478220880 ڃ 4478221200 20 >>> foo 10 https://medium.com/@meghamohan/mutable-and-immutable-side-of-python-c2145cf72747 Decorators They are functions which modify the functionality of other functions. Higher order functions. -
Enforcing Abstract Immutability
Enforcing Abstract Immutability by Jonathan Eyolfson A thesis presented to the University of Waterloo in fulfillment of the thesis requirement for the degree of Doctor of Philosophy in Electrical and Computer Engineering Waterloo, Ontario, Canada, 2018 © Jonathan Eyolfson 2018 Examining Committee Membership The following served on the Examining Committee for this thesis. The decision of the Examining Committee is by majority vote. External Examiner Ana Milanova Associate Professor Rensselaer Polytechnic Institute Supervisor Patrick Lam Associate Professor University of Waterloo Internal Member Lin Tan Associate Professor University of Waterloo Internal Member Werner Dietl Assistant Professor University of Waterloo Internal-external Member Gregor Richards Assistant Professor University of Waterloo ii I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public. iii Abstract Researchers have recently proposed a number of systems for expressing, verifying, and inferring immutability declarations. These systems are often rigid, and do not support “abstract immutability”. An abstractly immutable object is an object o which is immutable from the point of view of any external methods. The C++ programming language is not rigid—it allows developers to express intent by adding immutability declarations to methods. Abstract immutability allows for performance improvements such as caching, even in the presence of writes to object fields. This dissertation presents a system to enforce abstract immutability. First, we explore abstract immutability in real-world systems. We found that developers often incorrectly use abstract immutability, perhaps because no programming language helps developers correctly implement abstract immutability. -
Java: Odds and Ends
Computer Science 225 Advanced Programming Siena College Spring 2020 Topic Notes: More Java: Odds and Ends This final set of topic notes gathers together various odds and ends about Java that we did not get to earlier. Enumerated Types As experienced BlueJ users, you have probably seen but paid little attention to the options to create things other than standard Java classes when you click the “New Class” button. One of those options is to create an enum, which is an enumerated type in Java. If you choose it, and create one of these things using the name AnEnum, the initial code you would see looks like this: /** * Enumeration class AnEnum - write a description of the enum class here * * @author (your name here) * @version (version number or date here) */ public enum AnEnum { MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY } So we see here there’s something else besides a class, abstract class, or interface that we can put into a Java file: an enum. Its contents are very simple: just a list of identifiers, written in all caps like named constants. In this case, they represent the days of the week. If we include this file in our projects, we would be able to use the values AnEnum.MONDAY, AnEnum.TUESDAY, ... in our programs as values of type AnEnum. Maybe a better name would have been DayOfWeek.. Why do this? Well, we sometimes find ourselves defining a set of names for numbers to represent some set of related values. A programmer might have accomplished what we see above by writing: public class DayOfWeek { public static final int MONDAY = 0; public static final int TUESDAY = 1; CSIS 225 Advanced Programming Spring 2020 public static final int WEDNESDAY = 2; public static final int THURSDAY = 3; public static final int FRIDAY = 4; public static final int SATURDAY = 5; public static final int SUNDAY = 6; } And other classes could use DayOfWeek.MONDAY, DayOfWeek.TUESDAY, etc., but would have to store them in int variables. -
(8 Points) 1. Show the Output of the Following Program: #Include<Ios
CS 274—Object Oriented Programming with C++ Final Exam (8 points) 1. Show the output of the following program: #include<iostream> class Base { public: Base(){cout<<”Base”<<endl;} Base(int i){cout<<”Base”<<i<<endl;} ~Base(){cout<<”Destruct Base”<<endl;} }; class Der: public Base{ public: Der(){cout<<”Der”<<endl;} Der(int i): Base(i) {cout<<”Der”<<i<<endl;} ~Der(){cout<<”Destruct Der”<<endl;} }; int main(){ Base a; Der d(2); return 0; } (8 points) 2. Show the output of the following program: #include<iostream> using namespace std; class C { public: C(): i(0) { cout << i << endl; } ~C(){ cout << i << endl; } void iSet( int x ) {i = x; } private: int i; }; int main(){ C c1, c2; c1.iSet(5); {C c3; int x = 8; cout << x << endl; } return 0; } (8 points) 3. Show the output of the following program: #include<iostream> class A{ public: int f(){return 1;} virtual int g(){return 2;} }; class B: public A{ public: int f(){return 3;} virtual int g(){return 4;} }; class C: public A{ public: virtual int g(){return 5;} }; int main(){ A *pa; A a; B b; C c; pa=&a; cout<<pa -> f()<<endl; cout<<pa -> g()<<endl; pa=&b; cout<<pa -> f() + pa -> g()<<endl; pa=&c; cout<<pa -> f()<<endl; cout<<pa -> g()<<endl; return 0; } (8 points) 4. Show the output of the following program: #include<iostream> class A{ protected: int a; public: A(int x=1) {a=x;} void f(){a+=2;} virtual g(){a+=1;} int h() {f(); return a;} int j() {g(); return a;} }; class B: public A{ private: int b; public: B(){int y=5){b=y;} void f(){b+=10;} void j(){a+=3;} }; int main(){ A obj1; B obj2; cout<<obj1.h()<<endl; cout<<obj1.g()<<endl; cout<<obj2.h()<<endl; cout<<obj2.g()<<endl; return 0; } (10 points) 5. -
Exploring Language Support for Immutability
Exploring Language Support for Immutability Michael Coblenz∗, Joshua Sunshine∗, Jonathan Aldrich∗, Brad Myers∗, Sam Webery, Forrest Shully May 8, 2016 CMU-ISR-16-106 This is an extended version of a paper that was published at ICSE [11]. Institute for Software Research School of Computer Science Carnegie Mellon University Pittsburgh, PA 15213 ∗School of Computer Science, Carnegie Mellon University, Pittsburgh, PA, USA ySoftware Engineering Institute, Carnegie Mellon University, Pittsburgh, PA, USA This material is supported in part by NSA lablet contract #H98230-14-C-0140, by NSF grant CNS-1423054, and by Contract No. FA8721-05-C-0003 with CMU for the operation of the SEI, a federally funded research and development center sponsored by the US DoD. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect those of any of the sponsors. Keywords: Programming language design, Programming language usability, Immutability, Mutability, Program- mer productivity, Empirical studies of programmers Abstract Programming languages can restrict state change by preventing it entirely (immutability) or by restricting which clients may modify state (read-only restrictions). The benefits of immutability and read-only restrictions in software structures have been long-argued by practicing software engineers, researchers, and programming language designers. However, there are many proposals for language mechanisms for restricting state change, with a remarkable diversity of tech- niques and goals, and there is little empirical data regarding what practicing software engineers want in their tools and what would benefit them. We systematized the large collection of techniques used by programming languages to help programmers prevent undesired changes in state. -
Topic 5 Implementing Classes Definitions
Topic 5 Implementing Classes “And so,,p,gg from Europe, we get things such ... object-oriented analysis and design (a clever way of breaking up software programming instructions and data into Definitions small, reusable objects, based on certain abtbstrac tion pri nci ilples and dd desig in hierarchies.)” -Michael A . Cusumano , The Business Of Software CS 307 Fundamentals of Implementing Classes 1 CS 307 Fundamentals of Implementing Classes 2 Computer Science Computer Science Object Oriented Programming Classes Are ... What is o bject or iente d programm ing ? Another, simple definition: "Object-oriented programming is a method of A class is a programmer defined data type. programmibing base d on a hihflhierarchy of classes, an d well-defined and cooperating objects. " A data type is a set of possible values and What is a class? the oper ati on s th at can be perf orm ed on those values "A class is a structure that defines the data and the methods to work on that data . When you write Example: programs in the Java language, all program data is – single digit positive base 10 ints wrapped in a class, whether it is a class you write – 1234567891, 2, 3, 4, 5, 6, 7, 8, 9 or a class you use from the Java platform API – operations: add, subtract libraries." – Sun code camp – problems ? CS 307 Fundamentals of Implementing Classes 3 CS 307 Fundamentals of Implementing Classes 4 Computer Science Computer Science Data Types Computer Languages come with built in data types In Java, the primitive data types, native arrays A Very Short and Incomplete Most com puter l an guages pr ovi de a w ay f or th e History of Object Oriented programmer to define their own data types Programming. -
1 Immutable Classes
A Broken Time Period Class Computer Science and Engineering The Ohio State University public class Period { private Date start; Immutable Classes private Date end; Computer Science and Engineering College of Engineering The Ohio State University public Period(Date start, Date end) { assert (start.compareTo(end) > 0); //start < end this.start = start; this.end = end; Lecture 8 } public Date getStart() { return start; } public Date getEnd() { return end; } } Questions Problem: Aliasing Computer Science and Engineering The Ohio State University Computer Science and Engineering The Ohio State University What is an invariant in general? Assignment in constructor creates an alias Ans: Client and component both have references to the same Date object Class invariant can be undermined via alias What is an invariant for class Period? Date start = new Date(300); Ans: Date end = new Date (500); Period p = new Period (start, end); end.setTime(100); //modifies internals of p Why is this an invariant for this class? Solution: “defensive copying” Ans: Constructor creates a copy of the arguments Copy is used to initialize the private fields Metaphor: ownership A Better Period Class Good Practice: Copy First Computer Science and Engineering The Ohio State University Computer Science and Engineering The Ohio State University public class Period { private Date start; When making a defensive copy of private Date end; constructor arguments: public Period(Date start, Date end) { First copy the arguments assert (start.compareTo(end) > -
Declare Class Constant for Methodjava
Declare Class Constant For Methodjava Barnett revengings medially. Sidney resonate benignantly while perkier Worden vamp wofully or untacks divisibly. Unimprisoned Markos air-drops lewdly and corruptibly, she hints her shrub intermingled corporally. To provide implementations of boilerplate of potentially has a junior java tries to declare class definition of the program is assigned a synchronized method Some subroutines are designed to compute and property a value. Abstract Static Variables. Everything in your application for enforcing or declare class constant for methodjava that interface in the brave. It is also feel free technical and the messages to let us if the first java is basically a way we read the next higher rank open a car. What is for? Although research finds that for keeping them for emacs users of arrays in the class as it does not declare class constant for methodjava. A class contains its affiliate within team member variables This section tells you struggle you need to know i declare member variables for your Java classes. You extend only call a robust member method in its definition class. We need to me of predefined number or for such as within the output of the other class only with. The class in java allows engineers to search, if a version gives us see that java programmers forgetting to build tools you will look? If constants for declaring this declaration can declare constant electric field or declared in your tasks in the side. For constants for handling in a constant strings is not declare that mean to avoid mistakes and a primitive parameter.