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Communicating in Code: Naming

Communicating in Code: Naming. Programming Studio Spring 2009. What’s the Purpose of Coding?. What’s the Purpose of Coding?. To give the computer instructions?. What’s the Purpose of Coding?. To give the computer instructions. What’s the Purpose of Coding?.

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Communicating in Code: Naming

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  1. Communicating in Code:Naming Programming Studio Spring 2009

  2. What’s the Purpose of Coding?

  3. What’s the Purpose of Coding? • To give the computer instructions?

  4. What’s the Purpose of Coding? • To give the computer instructions

  5. What’s the Purpose of Coding? • To give the computer instructions • To demonstrate your skill?

  6. What’s the Purpose of Coding? • To give the computer instructions • To demonstrate your skill

  7. What’s the Purpose of Coding? • To give the computer instructions • To demonstrate your skill • An effective way to express ideas of what you want the computer to do

  8. What’s the Purpose of Coding? • An effective way to express ideas of what you want the computer to do • Communication! • To the computer • To yourself (later on) • To others

  9. What about Documentation? • External documentation is very useful, but has its own problems • Can be out of date/inconsistent with program • Maintained separately (multiple files) • Often for a different audience • developer vs. user • Clearly written code can be more important than well-written documentation of that code

  10. Communicating in Code • Choosing good names • Including appropriate comments • Following good layout and style • These are all critical to documentation, and with good naming, commenting, and layout, other documentation may be unnecessary!

  11. Names • We assign names throughout a program • Give identity • Imply behavior/purpose • Provide recognition

  12. What gets named? • Variables • Functions • Types/classes • Namespaces • Macros • Source Files

  13. Choosing Names • Sometimes there are naming conventions • If you work at a company that has an agreed convention, follow it! • But, there are several “wise” ideas to consider when choosing names.

  14. Naming Considerations Be sure it’s not a reserved name (Duh!) Sometimes it’s easy to forget… • Make it informative • Keep it concise • Make it memorable • Make it pronounceable

  15. Informative Names • The amount of information a name needs depends on its scope – understand it when seen • Use descriptive names for globals, short names for locals • Large routines/loops need more descriptive names s = 0; for (WhichGroup=0; WhichGroup<num; WhichGroup++) { s += G[WhichGroup].n(); }

  16. Informative Names • The amount of information a name needs depends on its scope – understand it when seen • Use descriptive names for globals, short names for locals • Large routines/loops need more descriptive names nAnimals = 0; for (i=0; i<NumAnimalGroups; i++) { nAnimals += AnimalGroup[i].NumberInGroup(); }

  17. Descriptive Names • Names should convey what it represents or does, unless obvious from context • Describe everything a routine does • Print() vs. PrintAndCloseFile() • Avoid meaningless or vague names • HandleData(), PerformAction(), etc.

  18. Descriptive Names • Procedures: Active names • Verb followed by noun • AnotherStudent(s) vs. AddStudent(s) • Functions different: give return value • GetNumStudents() vs. numStudents() • Booleans: Be clear what is returned • checkEOF vs. isEOF

  19. Consistent Names • Key: Be Consistent! • nKids, numKids, num_kids, NumKids, nkids, Number_Kids, numberofkids • Write1stObject(), WriteSecondObject(), write_third_object() • averageSalary vs. salaryMinimum • Use related names for related operations • OpenFile(): CloseFile() vs. fclose() • open/close, first/last, old/new, min/max, etc.

  20. Name Length • Tradeoff between description and visual space • Moderate-length names tend to be best • 8-20 characters • If a glance at the code seems like it has lots of short or lots of long names, use caution! • Scope plays a role • Rarely-used functions might be longer

  21. Other Random Naming Considerations • Beware of “temp” variables • Be careful of reusing variable names • Be careful of overloading names • Avoid intentional misspellings • Consider pronunciation

  22. Conventions • Lots of conventions out there • Conventions help convey information away from its definition • Very useful for larger groups/programs • Examples: • Globals have initial capital letters • Constants are in ALL CAPS • Etc.

  23. Common Naming Conventions • Beginning/ending with a p if a pointer • Starting with n for a number • i, j are integer indices • s is a string, c or ch are characters

  24. Hungarian Naming Convention • Base types: • wn Window • scr Screen Region • fon Font • ch Character • pa Paragraph • Eg: wnMain, scrUserWorkspace

  25. Hungarian Naming Convention • Prefixes • a array • c count • d difference between two variables • e element of array • g global variable • h handle • i index into array • e.g. iwnUserView = index into array of windows giving user views

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