1. Coding Standards Producing readable, maintainable code

2. Maintainability ● Cons i stency Consistency Consisstency ● Source code is written for humans to read. Not computers. ● Want to provide as much information as possible to the next person who reads the code – even if that person is you ● Consistency, in the form of conventions, gives lots of extra information

3. Maintainability ● Coding Standards – what are they? – Naming conventions ● How to name classes, variables, files etc. – Code Layout ● Indentation ● Comments – Usage of the language ● Which features to avoid ● Preferred methods for accomplishing tasks

4. Naming Conventions ● What are they? – Method for selecting names for variables, classes, parameters to functions etc. e.g. : ComputeTumourGrowth(OdeSystem &rTumourOdes) { AbstractOdeSolver *pOdeSolver = new RungeKuttaOdeSolver();... some more code... pOdeSolver->Solve(rTumourOdes); }

5. Code layout ● Consistent brace style – braces at start of new line, 4 space indentation if (valueToTest == comparison) { doTheGoodStuff(); } else { doSomethingElse(); } ● why? – Easiest to read, know where to look to find the matching brace – Avoids problem with no brace if statement

6. Code layout ● Consistent brace style //Potentially buggy: if (valueToTest == comparison) doTheGoodStuff(); ● C++ allows if statement without braces as above ● Leads to hard to spot bug when adding another statement: if (valueToTest == comparison) doTheGoodStuff(); someValue = 1.5; //this will always be executed ● If you always use braces, one less bug to find

7. Code layout ● Comments – Describe the intent of the programmer – Document tricky sections of the program – Provide a way of adding metadata e.g. physical units ● Aim is to Describe, rather than Duplicate: // initalize voltage to zero int voltage = 0.0; int voltage = 0.0; // Transmembrane potential (mV)

8. Code layout ● Comments – Use comments to lay out skeleton for code – Helps to solidify the algorithm in your mind – Afterwards – no need to write more comments! // Initialise stiffness matrix // Add boundary conditions // Assemble linear system // Set initial conditions in Solution vector // Solve linear system

9. Code layout ● Comments == Documentation – We want to keep the documentation in sync with the code – Don't want to write the same thing twice – Have to write comments anyway..... ● Doxygen - generates HTML / PDF / XML from code : /** Computes the volume of a standard cone. * * @param baseRadius The radius of the cone base (cm) * @param height The height of the cone (cm) * * @return The volume of the cone (cm^3) */ double ComputeConeVolume(double baseRadius, double height) {.... }

10. Usage of Language ● C++ lets you be very very clever... ● Don't be very very clever. ● Don't do things like this : struct X { static bool f( int* p ) { return p && 0[p] and not p[1]>>p[2]; }; ● Be as clear as you can, even if it takes more lines of code

11. Final notes The time you spend typing is a tiny fraction of the time you spend coding. Code clearly. Save time. Drink tea and eat doughnuts.