SmartCalc v3.0

Implementation of SmartCalc v3.0 in Python.

Contents

1. Chapter I
   1.1. Introduction
2. Chapter II
   2.1. MVP pattern
   2.2. MVVM pattern
3. Chapter III
   3.1. Part 1
   3.2. Part 2
   3.3. Part 3
   3.4. Part 4
   3.5. Part 5
4. Chapter IV

Chapter I

Thomas was standing outside the painfully familiar club, which now looked completely abandoned. Seb hasn't been seen in months and that's probably why.
When Thomas received a text message with no name but a familiar address, at first he thought it was Sebastian and jumped on the first flight to California. And even now he hopes that it is Seb who will show up at the time given in the message. However, the hopes began to fade.

- "I thought this was a popular place, a voice behind him brought Thomas out of his musings."

- "What? Yes, it used to be like that," - Thomas replied confusedly to the stranger.

- "A guy I know was bragging about it. Said his Dad used to run the place and serve the best non-alcoholic mojitos in Compton. I wish I'd had time to get here earlier when it still worked. I'm John, by the way."

- "I’m Thomas. So, you knew Sebastian?"

- "Yes, he and I worked in the same department. Well, he was interning there, until one day he suddenly disappeared without any word. And you?"

- "We grew up in the same neighborhood. I haven't heard from him lately either. I got a message with a familiar address, so I thought it might be from him."

- "A message, you say? With an address and time?" - John raised an eyebrow.

- "And a promise of answers to all questions, yes," Thomas replied. "It looks like we are here for a reason. And it looks like we're not the only ones," Thomas turned back and noticed a girl looking around the square in front of the jazz club. "Let me guess, a mysterious text message with the promise of answers to all your questions led you here, too?" Thomas asked the girl.

- "Yes, exactly," she answered after a little thought.

- "Well, now there's three of us!" John exclaimed. "Instead of answers, we only get more questions. I'm John, by the way, and this is Thomas. We literally just got here and met. And you are...?"

- "Eve."

- "Well, nice to meet you, Eve," said John. "I'm curious to hear your guesses about why we're here and what we're expecting," he hadn't finished talking when another cab pulled up next to them, and a young guy jumped out, dropping his bag on the way.

- "Chuck?! And you're here, too?" - Eve said, slightly surprised.

- "Oh, hi, Eve! What a far-off place to meet. How small the world is! And what do you mean, here? Did you get that weird text message, too?" Chuck seemed to be out of breath, constantly looking around for either potential dangers or something interesting. "I hope I'm not too late."

- "We all got this text here," John interjected. "I'm John, it's Thomas."

- "I'm Chuck. Never thought it would be such a mysterious meeting in the middle of nowhere," Chuck said in response, looking around.

- "It's not exactly nothing here, though," Thomas replied. "Until a few months ago there was a nice lively jazz club here, owned by the father of a good friend of mine. Who, as it turned out, was an acquaintance of John's. He was a colleague of yours, wasn't he? Except neither John nor I had heard from him in over three months. And the club... Well, you can see how it's turned out," Thomas looked sadly at the building.

- "Where did you work?" - Eve asked John.

- "A local division of SIS," John muttered back. "Administration of network applications and configuration of computer hardware."

- "Chuck and I are also from SIS. Different departments and the Eastern division, but still," Eve said thoughtfully. "And where do you work, Thomas?"

- "Advanced Solutions Inc. Daughter of SIS, transferred there quite recently. I had to take a vacation to get here, but I was seriously worried about Seb, and apparently not for nothing. Turns out we're all related to SIS in one way or another."

- "And not only to it, right, Eve?" Chuck said. "I've got some documents here that I think you might find interesting, so where are they..."
Who knows where this conversation would have gone if not for the simultaneous beeping and vibrating of smartphones in everyone's pockets that occurred at that moment.

Greetings to all! I'm very happy that you were interested and were able to get to your destination right in time. You are gathered here for a reason and will indeed get all the answers. But only after a little test. There is one task that they liked to test me on. But now it's time to switch places a little bit. Prove that you are ready and able to handle the tasks ahead, and then I will answer all of your questions. A test with details is already waiting for you in your personal repositories. Please begin immediately. Thank you.

Thomas thoughtfully reread the text over and over again, and only Chuck's quiet whisper broke the silence:

- "The Terminator..." he whispered.

Introduction

In this project you will implement an extended version of the usual calculator in the Python programming language, which implements the same functions as the previously developed application in the SmartCalc v2.0 project. You will improve your skills in the new programming language, learn the MVP or MVVM pattern, and add the help and history functionality to the application.

Chapter II

MVP pattern

The MVP pattern has two components in common with MVC: the model and the view. But it replaces the controller with a presenter.

The presenter implements the interaction between the model and the view. When the view notifies the presenter that the user has done something (e.g., pressed a button), the presenter decides to update the model and synchronizes all changes between the model and the view. However, the presenter does not interact with the view directly. Instead, it uses an interface to communicate. This allows all components of the application to be tested individually afterwards.

MVVM pattern

MVVM is a more modern update of MVC. The main purpose of MVVM is to provide a clear separation between the presentation and model layers. MVVM supports two-way data binding between View and ViewModel components.

The view acts as a subscriber to property value change events provided by the view model (ViewModel). If a property has changed in the view model, it notifies all subscribers about it, and the view, in turn, requests the updated property value from the view model. If the user interacts with an interface element, the view calls the corresponding command provided by the view model.

A view model is on the one hand an abstraction of a view, and on the other hand a wrapper of data from the model to be bound. In other words, it contains the model transformed to the view, as well as the commands the view can use to affect the model.

Chapter III

Part 1. SmartCalc v3.0 implementation

You need to implement SmartCalc v3.0:

• The program must be developed in Python 3.11
• The program code must be in the src folder
• You must stick to Google Code Style when writing code
• You need to develop a desktop application
• Prepare the installer, which will install the application to the system with the standard settings (installation path, creating shortcut)
• Prepare an implementation with a graphical user interface for Mac OS, based on any GUI library or framework (GUI layer implementation in HTML/CSS/JS is acceptable)
• The program must be implemented using the MVVM or MVP pattern, and
  • there should be no business logic code in the view code
  • there must be no interface code in the model, presenter and view model
• The "core" of the calculator in the form of an algorithm for the formation and calculation of the Polish notation and various computational functions connect as a dynamic library in C/C++ from the SmartCalc v1.0 or SmartCalc v2.0 projects
• The model should be a "core" with a wrapper in Python
• The model must have all the calculator's functionality so that it can be used in the future without the other layers
• Prepare full coverage of methods in the model layer with unit tests
• The application should have a help section with a description of the program interface in random form
• The program must save the history of operations, allow loading expressions from the history and clear the entire history
• History must be saved between runs of the application
• Both integers and real numbers, written either via a point or in exponential form, can be input to the program
• Calculation should be performed after the complete entry of the calculated expression and pressing the symbol =
• Calculation of arbitrary bracketed arithmetic expressions in infix notation
• Calculation of arbitrary bracketed arithmetic expressions in infix notation with substitution of x variable as a number
• Plotting a function defined using an expression in infix notation with the variable x (with coordinate axes, scale marker, and grid with adaptive step)
  • It is not necessary to provide the user with the ability to change the scale
• The range of definition and the range of value of the functions are at least limited to numbers from -1000000 to 1000000
• To plot a function it is necessary to additionally specify the displayed area of definition and area of value
• Checked accuracy of the fractional part is at least 7 decimal places
• The user must be able to enter up to 255 characters
• Bracketed arithmetic expressions in infix notation must support the following arithmetic operations and mathematical functions:

  • Arithmetic operators:

    Operator name	Infix Notation (Classic)	Prefix notation (Polish notation)	Postfix notation (Reverse Polish notation)
    Parentheses	(a + b)	(+ a b)	a b +
    Addition	a + b	+ a b	a b +
    Subtraction	a - b	- a b	a b -
    Multiplication	a * b	* a b	a b *
    Division	a / b	/ a b	a b \
    Rasing to the power	a ^ b	^ a b	a b ^
    Remainder of division	a mod b	mod a b	a b mod
    Unary plus	+a	+a	a+
    Unary minus	-a	-a	a-

    Please note that the multiplication operator contains a mandatory * sign. Processing an expression with the * sign omitted is optional and left to the developer's discretion

    Function description	Function
    Calculates cosine	cos(x)
    Calculates sine	sin(x)
    Calculates tangent	tan(x)
    Calculates arc cosine	acos(x)
    Calculates the arcsine	asin(x)
    Calculates arctangent	atan(x)
    Calculates square root	sqrt(x)
    Calculates natural logarithm	ln(x)
    Calculates decimal logarithm	log(x)

Part 2. Bonus. Loan сalculator

Provide a special mode "loan calculator" (you can take websites like banki.ru and calcus.ru as an example):

• Input: total loan amount, term, interest rate, type (annuity, differentiated)
• Output: monthly payment, overpayment for the loan, total repayment

Part 3. Bonus. Deposit calculator

Provide a special mode "deposit calculator" (you can take websites like banki.ru and calcus.ru as an example):

• Input: deposit amount, deposit term, interest rate, tax rate, periodicity of payments, capitalization of interest, list of additions, list of partial withdrawals
• Output: accrued interest, tax amount, amount on deposit by the end of the term

Part 4. Bonus. Configuration and logging

Add settings to the app:

• Add reading of settings from configuration file when the program runs
• Include in the configuration file 3 or more parameters to choose from, such as background color, font size, etc.
• Add descriptions of editable parameters to help

Add logging to the application:

• Store operation history in logs
• Save logs in the logs folder, one file per rotation period
• It should be possible to set the period of logs rotation (hour/day/month)
• Files must be named according to the following pattern: logs_dd-MM-yy-hh-mm-ss ( the time of file creation )

Part 5. Bonus. Cross-platform

Make your app cross-platform:

• Add support for Linux
• Add support for Windows
• The installer should also be available for Linux and Windows (several different installers are allowed)

Chapter IV

Thomas finished the calculator without too much trouble. He already knew Python, so he quickly put together a simple desktop application. The other guys seemed to be finishing their work, too.
As soon as everyone had finished their work, new messages from an anonymous person popped up on their phones:

Thank you. I see you all did well. That's great, even though the algorithms predicted it from the beginning. Please set up a secure connection to the server specified in the following message and connect to the specified chat room. There we will be able to talk freely and calmly. I also have some special information for Thomas and John regarding your friend, Seb. I will expect you in the chat room!

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