Questions

• What tools do you use for developing code?
• How do you compile or execute the code?
• How do you debug the code?
• How do you rename a function or variable across the entire project?
• How do you search for files that uses a function or class?
• Is choosing right tools important?

General workflow in developing code

• Writing the code
• Compiling the code
• Executing the code
• Debugging the code
• Tracking the code with version control
• Searching files, functions, classes, etc

Tools available for developing code

• Terminal-based text editors for writing code (e.g. vi/vim, nano, emacs, etc)
• Command line tools
  • for compiling code (e.g. gcc, GFortran, javac, etc)
  • for executing code (e.g. python and java command line interpreters, etc )
  • for debugging code (e.g. gdb, pdb, jdb, etc)
  • for version control (e.g. git)

• Text-based code editors (e.g. sublime text, Atom, Visual Studio Code)

• Integrated development environments (IDEs) brings you “everything” you need to be a productive programmer to your finger tips
  • IDEs are developed to maximize programmer productivity
  • IDE is a self-contained package that allow you to write, compile, execute and debug code in the same place
  • IDE examples: Netbeans, Eclipse, PyCharm, Ruby Mine, Visual Studio

  

Terminal-based editors vs code editors vs IDEs

Terminal-based editors

• Terminal editors like Emacs and Vim are quite famous in Linux environments
• Steep learning curve
• Many terminal editors are limited to writing code/text, but you can customize them as needed
• General purpose editors and can be used for writing code in various programming languages
• One need to switch between a terminal editor, command line tools, compilers or interpreters for compiling and executing the code
• One need to switch between multiple tools for developing the code

Code editors

• Code editors are light-weight IDEs
• Mainly developed for writing code
• General purpose editors and can be used for writing code in various programming languages
• Support auto-completion, terminal integration, version control integration, etc

IDEs

• IDE is generally focused on a single language and contains the compiler/interpreter and debugger specific to the language
  • (e.g. not easy to use RStudio for developing code in Python and R)
• IDEs are developed to make software development faster and usually offer
  • code auto-completion, refactoring support
  • fast find of files, function, class
  • debug support, integrated build tools, source control management
• One IDE may not be fit for all programming languages
• IDEs do a lot of things on behalf of us
• The pro is that an IDE really integrates features you need. The cons is that you need to learn the in-and-outs of the IDE, especially the keyboard shortcuts, to reap the benefits.

Choosing between Terminal editor - code editor - IDE

• Choosing between a terminal editor or code editor or IDE largely depends on the personal preference, the particular programming language and the workflows

Demonstrating terminal editor (no need to type along)

• For demonstrating terminal editor we have selected Vim
• Vim is pre-installed on many operating systems
• Vim can be customized as needed, please check here

We are using a simple program that asks user input (integers) and prints the product of the given input.

def multiplication(first_number, second_number):
    return first_number * second_number

first_number = int(input("enter first number :"))
second_number = int(input("enter second number :"))

product_of_numbers = multiplication(first_number, second_number)

print("product of %s and %s is : %s" % (first_number,second_number,product_of_numbers))

• To open a file: vim filename
• To add text: Press i
• To save and exit vim: Hit Escape, then type :wq and hit Enter
• Multiple CLI tools have to be used
  • for executing: python interpreter
  • for debugging: python pdb module
  • version control: git
  • search and replacing code: grep and sed utilities

Demonstrating code editor

In this lesson we will give overview of a code editor and its functionality. We have selected Visual Studio Code (VS Code) to demonstrate the use of a code editor.

Note: Other code editors also offer similar features and support the functionality that we discuss in this lesson.

We start by opening VS Code.

• Start VS Code
• In the welcome dialog, choose “Open folder”
• Create new folder and give an appropriate name, e.g “Code_editor”

VS Code environment

The UI is divided into multiple areas.

• Editor - The main area to edit your files. You can open multiple editors side by side (up to 3)
• Activity Bar - Located on the far left-hand side, this lets you switch between views and gives you additional context-specific indicators
• Side Bar - Contains different views to assist you while working on your project
• Status Bar - Information about the opened project and the files you edit
• Panels - Displays integrated terminal, output or debug information, errors and warnings, etc

Activity Bar

• Explorer - to explore the current workspace/work folders or add
• Search - to search for files and replace variables
• Version Control - to track the code - e.g. git
• Debug - debugging window
• Extensions - for installing extensions (e.g. programming language specific plugins)

Command palette

• Keyboard can be used to access VS Code features
• Pressing Ctrl + Shift + P (Windows, Linux) brings up the Command Palette. ⇧⌘P (Mac)
  • you can access all the functionality of VS Code, including keyboard shortcuts for the most common operations.
  • e.g. new file, new folder, git commands

VS Code Settings/Preferences dialog

• Windows and Linux - File -> Preferences -> Settings (⌘,)
• macOS - Code -> Preferences -> Settings (⌘,)

• You can add your settings to user settings tab to override default settings e.g. add “editor.fontSize” to user settings and adjust it as needed

• Note: As you make modifications, the settings for current folder will be stored under the .vscode folder in your current folder
• You can use the keyboard shortcuts of your old editor (such as Sublime Text, Atom, and Vim) in VS Code. Plese check here for details

Windows users

• You can also attach your git bash to VS Code
• Open settings
• Add “terminal.integrated.shell.windows”: “C:\Program Files\Git\bin\bash.exe” to user settings
• Adjust the path based on your git bash

Using VS Code editor

We can use the code editors for writing code in multiple programming languages, let’s see how:

For demonstrating VS Code we are using a simple program that asks user input (integers) and prints the product of the given input.

For Python users

• Create a file by right clicking in explorer and select “New File”. Call the file multiplication.py
• VS Code shows the appropriate extensions to install
  • Alternatively you can “click extensions icon” -> “Search for Python”
• Install the Python extension
• The Python extension automatically detects Python interpreters that are installed in standard locations.

• You can also use the python.pythonPath in settings to point to an interpreter anywhere on your computer.

• Add the following Python code to the file:

def multiplication(first_number, second_number):
    return first_number * second_number

first_number = int(input("enter first number :"))
second_number = int(input("enter second number :"))

product_of_numbers = multiplication(first_number, second_number)

print("product of %s and %s is : %s" % (first_number,second_number,product_of_numbers))

• Run the code by “Right clicking” on editor -> “Run python code in terminal”

  Exercise:

• Add a new variable to take third number
• Modify the code to print out the multiplication of three numbers
• As you type in VS Code gives the recommendations

For C++ users

• Create a file by right clicking in explorer and select “New File”. Call the file multiplication.cpp
• VS Code shows the appropriate extensions to install
  • Alternatively you can “click extensions icon” -> “Search for C++”
• Install the C/C++ extension
• Add the following C++ code to the file:

#include <iostream>

using namespace std;

int main(int argc, char const *argv[]) {

  double firstNumber, secondNumber, productResult;

  std::cout << "Enter first number" << '\n';
  std::cin >> firstNumber;

  std::cout << "Enter second number" << '\n';
  std::cin >> secondNumber;

  productResult = firstNumber * secondNumber;

  std::cout << "product of given input is " << productResult << '\n';

  return 0;
}

• To build C++ application from VS Code, you will need to generate a tasks.json file:
• Open the Command Palette
  • Select the Tasks: Configure Tasks command
  • click Create tasks.json file from templates, and you will see a list of task runner templates
  • Select Others to create a task which runs an external command
  • Change the the command in tasks.json file to the command line expression you use to build your application (for example g++)
  • Add any required args (for example -g to build for debugging)
  • You can also change the label to be more descriptive
• Run the code by opening command palette -> run task -> continue without scanning

For debugging, please visit this page

Exercise:

• Add a new variable to take third number
• Modify the code to print out the multiplication of three numbers
• As you type in VS Code gives the recommendations

For FORTRAN users

• Create a file by right clicking in explorer and select “New File”. Call the file multiplication.f90

• VS Code shows the appropriate extensions to install
  • Alternatively you can “click extensions icon” -> “Search for fortran”

• Install the Modern Fortran extension

• Add the following fortran code to the file:

program product
    implicit none

    integer :: i, j

    print *, "enter two integers"
    read (*,*) i, j

    print *, "product of given input is", i * j
end program

• To build fortran application from VS Code, you will need to generate a tasks.json file:
• Open the Command Palette
  • Select the Tasks: Configure Tasks command
  • click Create tasks.json file from templates, and you will see a list of task runner templates.
  • Select Others to create a task which runs an external command.
  • Change the command in tasks.json file to the command line expression you use to build your application (for example gfortran).
  • You can also change the label to be more descriptive.
• Run the code by opening command palette -> run task -> continue without scanning

Exercise:

• Add a new variable to take third number
• Modify the code to print out the multiplication of three numbers
• As you type in VS code gives the recommendations

Tracking the code

• You can initialize a git repository from the version control tab
• Open folder where you want to initialize git
• Use buttons + to stage and - to unstage
• Changes made to a staged file can be seen from the editor
• Commit changes
• You can also clone a remote repository and work with it (⇧⌘P - type git clone)

• TODO: make some changes and see how changes are shown by VS Code

Searching and replacing

• You can search and replace text from search bar
• As you navigate through change it shows the changes that are going to be done

Exercise:

• search where “firstnumber” variable is used
• replace “firstnumber” with “firstinput”

Debugging with VS Code

Python

• In case of Python, go to debug window and press green button
• Select “Python experimental”
• Debugger will start automatically

Pros and Cons

Terminal editors

• + Pre-installed on many operating systems

• + Supports various programming languages

• - steep learning curve
• - one needs to master keyboard shortcuts and CLI tools for using effectively

Code Editor

Code editors are light weight and general purpose

• + Easy to use

• + Supports various programming languages

• ±multi functional
• ±can be used for variety of tasks