Section 6 - Design, Testing and IDEs

Section 6 - Design, Testing and IDEs

1. Defensive Design

   • Defensive Design helps to ensure programs function properly
     • When programs are functioning properly they shouldn't ever break and never produce errors.
       • This is difficult to achieve even for large software companies who update software regularly
     • Programmers try to protect their software through defensive design
       • They will try to:
         • Anticipate how users may misuse their program, then attempt to prevent it from happening
         • Ensure their code is well-maintained
         • Reduce the number of errors in the code through testing
   • Make sure inputs can't be exploited
     • Input Sanitisation
       • Removing any unwanted characters before passing through the program
     • Input Validation
       • Checking if data meets certain criteria before passing it into the program
   • Authentication can help Protect Programs
     • This is used to confirm the identity of a user before they are allowed to access certain pieces of data or features of the program
   • Programs should be easy to maintain
     • A well-maintained program makes it easy for other programmers to understand what the code does
       • They should also be able to change parts of the source code without the risk of causing problems elsewhere
     • The following features improve maintainability:
       • Comments
       • Indentation
       • Relevant Variables
       • Use global variables when necessary

2. Translators

   • Computer Languages can be High-Level or Low-Level
     • Most languages that you're familiar with are high-level languages
       • This means that the source code is easy for humans to write, but computers need to translate it into machine code before they can read and run it
       • Examples of these are Python, C++, JavaScript, etc.
     • Low-Level languages are hard for humans to read and write but are easier for a computer to run
       • These languages are machine code and assembly languages
   • Translators convert programming languages into Machine Code
     • Computers only understand instructions given in machine code, so high-level and assembly languages need to be translated first
     • There are three types of translator:
       • Assemblers
         • These are used to turn assembly language into machine code
           • There are many types of assembly languages to support different types of CPU
       • Compilers
       • Interpreters
         • Compilers and interpreters are both used to turn High-Level code into machine code

3. Integrated Development Enviroments (IDEs)

   • IDEs have features to help programmers
     • An IDE is a piece of software that provides features to help a programmer to develop their program
       • Most IDEs will have similar features
   • Examples
     • Microsoft Visual Studio
     • Pycharm
     • Python Idle
   • Microsoft Visual Studio 2015 Example
   • Common Features of an IDE
     • A translator
     • Auto-documentation to help with the maintenance of programs
     • A Graphical User Interface builder so it's easier for the programmer to design a user interface by building it up graphically rather than designing it through source code

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