John.Wiley.and.Sons.Rapid.Mobile.Enterprise.Development.for.Symbian.OS.An.Introduction.to.OPL.Application.Design.and.Programming.May.2005.eBook-LinG (779881), страница 25
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On moving up to the Series 3a, he also upgradedhis copy of Money to the new computer. He was looking for a simpleHome Accounts application, but this new version (along with the new‘Accounts and Expenses’) insisted on double-entry bookkeeping, whichhe felt wasn’t necessary. So he wrote his own, using OPL.Al designed S3aBank (as it was originally called) to mirror the lookand feel of the original Money program. After six months of workingand tweaking it, he felt that S3aBank was good enough to be comparedwith the professional applications, and he released it onto the fledglingInternet, secretly hoping it would garner enough registrations to pay forthe Series 3a. It is now recognized as one of the most popular pieces ofOPL software ever, with over 10,000 sales across the myriad platformsit runs on.
When the Psion Series 5 launched, S5Bank was available thesame day. It was reworked with the Series 5mx, using the powerful newOPL Database Management System, and continued to sell very well.130WHERE NOW WITH OPL?RMRBank is now available for the Communicator and UIQ phones,and continues to be a popular application. After 10 years of coding,RMRBank is still doing exactly what its author needs, and is helpingthousands of people manage their finances as well.9.2 Fairway, by Steve LitchfieldSteve Litchfield is a full-time ‘PDA Specialist’ now, but back in the early1990s he was still working for a living! Unable to be away from any typeof computer over a two-week holiday in Scotland, Steve purchased aPsion Series 3.
In those days, the paper manuals weighed more than themachine, and with the help of the enclosed OPL documentation, Stevehad a working prototype of a golf game. Pitch and Putt, written purelyfor his own enjoyment, was uploaded to a few bulletin boards to seewhat sort of reaction it would get. It got a very good reaction, as Psionthemselves got in touch with Steve, and ‘Pitch and Putt’ was packagedon the first Games Compilation disk released for the Series 3.
Steve thenexplored the Shareware route, providing ‘the first hole free’ and askingfor the registration fee to get the rest of the holes.The success of this led to a full 18-hole tournament version. CalledFairway, it has been one of the most long-lived OPL games, goingthrough three major versions, adding in features for digital sounds, tosupport different devices, and continuing to be marketed in officialGames Compilations for the Series 3a and the Series 5 machines. Fairwaynow lives on in versions for both the Communicator and UIQ, in fullcolor, ready to continue to provide an excellent game of golf in themobile world.9.3 EpocSync, by Malcolm BryantMalcolm Bryant isn’t a programmer, but he’s still created one of the mostunusual OPL programs out there.
Malcolm found that he was constantlybeaming the same files between his Psion netBook and Revo during theday. So he decided to automate the process. EpocSync was the result. Onlining up the infrared ports of the two machines and running EpocSyncon both machines, they would connect to each other, and ensure thatthe latest copy of each file (in a list the user creates) is on each machine.EpocSync has the unusual distinction of being a program that has to talkto itself (when it is running on another machine). At each stage of thesync operation, each copy of the program needs to know where the otherprogram is so the correct messages and packets of information can besent between the machines.FINAL SUMMARY.
. . MOVING FORWARDS YOURSELF131After its release, EpocSync proved itself in two areas that Malcolmhad never considered, but was then able to improve upon in subsequentreleases. The first was that, because EpocSync was written completely inOPL, it would run happily on the Windows-based Symbian OS emulators.This meant that using EpocSync on both machines allowed users tosynchronize the files on their Psion directly onto the PC, bypassing theconnectivity suite. In essence, EpocSync and the SDK could be usedas a ‘Desktop PDA Companion’ program. Finally, Malcolm added insupport for FTP syncing with a third-party OPL extension. This used thesame EpocSync engine, but now instead of copying the files to and fromanother Psion, the files were backed up to a regular FTP server on theInternet, providing remote backup for those on the move and travellingaround a lot.9.4 Final Summary.
. . Moving Forwards YourselfSo now you have an understanding of OPL, what can you do? Well, aswith any programming language, it’s what you make of it that counts. Youcould build up a huge suite of applications for use inside your business,or in your personal life. You might just code something that alreadyexists, but that’s missing a key feature for you. And you may programand release apps on the Internet to gain recognition, or for profit. Thereare a large number of OPL programmers who have happily made a livingprogramming in OPL – with even more Symbian OS phones out there,perhaps this could be you?No matter what, OPL is now something you’ll be able to use in yourdaily life.
If you’re unsure about something, then try it. If you need toask for help, then the best starting point is the website for this book, orthe OPL Forums on All About Symbian (www.allaboutsymbian.com/),My Symbian (http://my-symbian.com/), and the OPL Wiki Website(www.allaboutopl.com/wiki). And when you do release an application,be sure to send an email to myself and the OPL Development Team tolet us know! You’ll find details on how to do this at the above sites.Part 2Introduction to Part 2: CommandListingAs well as a structured introduction to programming, this book willcontinue to act as an ongoing reference as you program OPL in themonths and years ahead.
The core of OPL is the commands that areavailable in the runtime for you to use. No matter what version ofOPL (UIQ, Series 60, or the Communicators) you use in the future, thiscommand list will always remain current.In fact, if you look back at the version of OPL that featured on the PsionSeries 3 Organizer in 1992, almost all the commands available then arefeatured in the current Symbian OS runtimes.Alphabetical Command ListingEvery OPL command is listed here, in a common format.Command NameThis is the command name as typed into any OPL source code.Command SyntaxA one-line example of the command, showing all the flags, variables,and their type, i.e.
if they are integer variables, strings, etc. You may havethe same command listed more than once. Some OPL commands haveoptional variables and flags, and each combination of these is listed. Agood example of this is the banner print command, gPRINTB.Short DescriptionA brief outline of the command and what it does.134INTRODUCTION TO PART 2: COMMAND LISTINGFull DescriptionSome commands will need little more than the short description. Othersneed explaining in more depth. Here we break down each command,and show code examples where required.Related CommandsAs it says, OPL commands that are connected to the command you arelooking up.Const.oph ListingThe Const.oph file is a header file full of constants, that you can use tomake your source code easier to read.
More details on using constantscan be found in Chapter 2. This list provides you with all the constants,and the values that they take, grouped by function.Appendix 1OPL Command List(Derived from last Symbian OS v5 OPL Documentation, shipped withinitial Series 80 OPL Release)ABSAbsolute value of a floating point numberUsage: a=ABS(x)Returns the absolute value of a floating pointnumber, that is, without any +/− sign. For exampleABS(−10.099) is 10.099.If x is an integer, you won’t get an error, but theresult will be converted to floating point. For exampleABS(−6) is 6.0.
Use IABS to return the absolute valueas a long integer.ACOSArccosineUsage: a=ACOS(x)Returns the arc cosine, or inverse cosine (COS-1) of x.x must be in the range −1 to +1. The numberreturned will be an angle in radians. To convert theangle to degrees, use the DEG function.ADDRAddress of variableUsage: a&=ADDR(variable)Returns the address at which a variable is storedin memory.The values of different types of variables are stored inbytes starting at ADDR(variable). See PEEK for details.The return type of this function should be a long integer,however, if the 64K memory limit is set via SETFLAGS,a& is guaranteed to fit into an integer.See UADD, USUB.136ADJUSTALLOCOPL COMMAND LISTAdjust memory allocationUsage: pcelln&=ADJUSTALLOC(pcell&,off&,am&)Opens or closes a gap at off& within the allocated cellpcell&, returning the new cell address or zero if out ofmemory.
off& is 0 for the first byte in the cell. Opensa gap if the amount am& is positive, and closes it ifnegative. An error will be raised if the cell addressargument is not in the range known by the heap.See also SETFLAGS if you require a 64K limit to beenforced on 32-bit target devices. If the flag is setto restrict the limit, pcelln& is guaranteed to fit intoan integer.See ALLOC.ALERTAlert dialogUsage: any ofr%=ALERT(m1$,m2$,b1$,b2$,b3$)r%=ALERT(m1$,m2$,b1$,b2$)r%=ALERT(m1$,m2$,b1$)r%=ALERT(m1$,m2$)r%=ALERT(m1$)Presents an alert – a simple dialog – with the messagesand keys specified, and waits for a response. m1$ is themessage to be displayed on the first line, and m2$ onthe second line.
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