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Speed geeking-lotusscript


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Speed geeking-lotusscript

  1. 1. The 12 step guide to LotusScript Bill Buchan hadsl
  2. 2. #1: How to Code• How to code • Code for maintenance • Code updates cost more than new code • Architect well. Get the data model right to start with.• Only code for performance, if required • Get it working before getting it working for speed• Why? • The highest cost in development is software maintenance • Make it easier for the person maintaining the app • It could be YOU 2
  3. 3. #2: How to Test• Test soon, test often, test completely • Look at test-driven development • Write the specification • Write the structure • Write the tests • Write the code • Automatic testing means: • Far easier to regression test all the time • Minimize run-time errors by: • Always assuming that data operations outside the current database may fail • Trapping all run-time errors and providing an execution path that fails safely 3
  4. 4. #2: How to Test (cont.)• Why test early? • Costs rise as the tests fail further away from development • Cheapest to most expensive are: • Unit tests — by the developer • User acceptance tests (UATs) — by the tester • End-user failure — by the user • The more tests you perform in unit testing: • The cheaper your development will be • The more professional your colleagues will think you are • The more your boss will like you 4
  5. 5. #3: “Measure Twice, Cut Once”• Spend more time thinking and less time coding• Think of at least TWO methods of solving a problem • The best approach is usually a blend of the two • Think about the data model!• Why? • More planning, less work• “You know it’s been a rough night when you wake up next to some code you don’t recognize.” – Bob Balaban 5
  6. 6. #4: Option Declare• You should always use “Option Declare”• Yes, but why? • If not, all variables are created at run-time as variants • This makes type-checking redundant • Data conversion costs ten times more performance! • And means all errors will be run-time errors • Remember: Test lots, test early • Use the strengths of the compiler to help you • Remember to always declare the type of variables and parameters - otherwise it defaults to variants! 6
  7. 7. #5: The List OperatorDim Pres list as StringPres(“George”) = “Bush”Pres(“Bill”) = “Clinton”Print “Georges’s last name is: “ + Pres(“George”)if not isElement(Pres(“Chad”)) then print “Chad wasn’tfound”forall thisPres in Pres Print listtag(thisPres) + “ “ + thisPresend forall• List stores a value with a unique lookup key • Pros: • It’s easy and it’s fast • It’s built right into LotusScript, since v4.5 • Cons: • You can’t directly read and write a list from a document item – convert to an array first 7
  8. 8. #6: Defensive Coding• Defensive coding is: • Assume the worst, check all input • On every function • Does this affect performance? Not usually. • A typical function looks like:Function mytest(p1 as String, p2 as String) asinteger mytest = false if p1=”” then exit function if p2=”” then exit function ... Now actually do something! .... mytest = trueend function 8
  9. 9. #7: Extending Arrays the Easy WaySub initialize() Dim myArray() as String redim myArray(0) call myExtend (myArray, “Hello Sailor”)end subfunction myExtend(S() as String, ns as String) as integer if (S(ubound(S)) <> “”) then redim preserve S(ubound(S)+1) S(ubound(S)) = ns extend = trueend function• Pros: • No need to keep separate index of array size • Automatically “trims”• Cons: • Slow with large arrays • Need to define some “empty” value 9
  10. 10. #8: Logging• If you have applications with scheduled Agents• Or, if you have a diverse range of clients • Then, you need to log your Agent (both client and scheduled) run-time status• Why? • Applications will break • You need to know when they break • Timing metrics for performance testing• Beware! • Don’t make the logging so slow that it affects application performance! 10
  11. 11. #8: Logging (cont.)• OpenLog is an OpenNTF Project: •• It provides a framework for collecting error logging • To use in your database: • Copy the script libraries from the OpenLog database • Update the code: Function test(param1 as String) as integer Test = false on error goto errorhandler ... Test = true exitFunction: exit function errorhandler: call logError() resume exitfunction end function 11
  12. 12. #8: Logging (cont.)• Example OpenLog output: 12
  13. 13. #9: Use NotesDateTime Instead of Strings!• Don’t store date/time values as Strings• Use NotesDateTime structures, and save them• Why? • You don’t know how the client will interpret dates • Is it dd/mm/yyyy or mm/dd/yyyy? • It means that views will be able to sort on dates• This happens more often than you think! • And things always break on the 13th of the month 13
  14. 14. #10: Always use full canonical names inreader/author fields!• Common names assume the same hierarchy as the server in use• Abbreviated names dont work• Always use multi-values for multiple names - sticking ‘;’ between names wont work• And always set the field to reader/author in LotusScript! 14
  15. 15. #11: Evaluate• Evaluate allows you to run @Functions within LotusScript• Sometimes faster, easier• Example: evaluate(|@unique|)• DON’T: • Overuse it. Lots of LotusScript functions mimic @functions • strRight == @StrRight 15
  16. 16. #12: “Trusted Servers”• Scheduled Agents cannot normally open databases on other servers • “Trusted Servers” field in R6 server document, security section allows servers to “trust” other servers • This allows you to centralize “collection” Agents • Caveat: Don’t trust servers in another domain!• Pros: • Simplifies architecture • Fewer Agents• Con: • Relies on fast, reliable network infrastructure … 16
  17. 17. #13: LSI_Info()/GetThreadInfo• LSI_INFO() gives some run-time information• Superceded by GetThreadInfo • GetThreadInfo(11) gives calling class • GetThreadInfo(10) gives function name • And lots more• Why? • Error trapping: We can track where we came from • We don’t have to pass lists of parameters to error trapping code • Prevents “cut-n-paste coding” errors ... 17
  18. 18. #13: LSI_Info()/GetThreadInfo (cont.) calling code... ... ExitFunction: exit function errorhandler: Call RaiseError()Function RaiseError() resume exitFunction Dim thisType As String end function Dim es as String thisType = Typename(Me) Not a class, use the calling module instead If (thisType = "") Then thisType = Getthreadinfo(11) es = thisType & "::" & Getthreadinfo(10) & ": " If (Err = 0) Then es = es + "Manually raised an error" Else es = es + "Run time error: (" + Trim(Str(Err)) + ") " + _ Error$ + " at line: "+ Trim(Str(Erl)) End If Print esend function 18
  19. 19. OkayI added a new step 19
  20. 20. Done! 20