The language was originally called Organiser Programming Language, developed by Psion Ltd for the Psion Organiser. Designed by Colly Myers with the first iteration implemented by Richard Harrison and Martin Stamp. The first implementation was for the original Psion Organiser, and it came bundled with the Science, Finance and Math data packs. It became truly accessible as built-in software in the Psion Organiser II, and the language went on to be used in the Psion Series 3 and later. After Psion retired from the portable digital assistant market, the project was delayed until 2003, when the fledgling Symbian Developer Program released it as open source. The language is now developed on SourceForge in the opl-dev project. The language is not available from Symbian OS v8 and later, mainly due to lack of interest and support from major Symbian licencees Nokia and Sony Ericsson. Hence, OPL will most likely never be made available for the newer generation of Symbian OS phones such as Sony Ericsson P990, M600, W950, P1i and Nokia E61i and E90. As of 2010, Nokia device developers are encouraged to use Python for S60 instead.
Examples
Here is the console version of a Hello world program: PROC main: PRINT "Hello World!" PAUSE 40 ENDP
And here is a GUI version for Nokia's Series 80 user interface: CONST KKeyEnter%=13 PROC hello: dINIT "Hello" dTEXT "","Hello World!" dBUTTONS "OK",KKeyEnter% DIALOG ENDP OPL is a structured programming language. OPL programs contain PROCedures, which are much like functions in other programming languages.
The dINIT keyword in this example initializes a dialog box. The first argument of the dialog is an optional string, which is used for the title of the dialog, displayed in the title bar.
The dTEXT function displays text, with two compulsory arguments: a left-aligned 'prompt' string, and a main string.
The dBUTTONS keyword allows you to put buttons on the dialog box - here there is a button with the text "OK". The second argument to each button is both the special notation of the shortcut key for that button and the dialog's return code, in this case the "Enter" key.
Finally, the DIALOG keyword is required for the previously initialized dialog box to be shown on the screen.
Testing dialog responses
An example: PROC test: dINIT "Your Challenge" dTEXT "","Will your answer to this question be no?" dBUTTONS "Yes",%y,"No",%n IF DIALOG=%y PRINT "No it wasn't!" ELSE PRINT "Yes it was!" ENDIF GET ENDP
In this cruel interrogative program, the Yes button is assigned the shortcut of Ctrl+y, while No has Ctrl+n, represented by %y and %n respectively. The user's input from the DIALOG is tested in the IF statement, PRINTing appropriate responses to the screen. Note that the 'GET' keyword, which gets user input without using a dialog box, is here used simply to wait for a keypress before terminating the program. The output from DIALOG can also be stored in a variable. Variables specific to a procedure must be declared with the LOCAL keyword; global variables are defined with the GLOBAL keyword.
Variable types
The table below uses an example variable called 'var'.
Minutiae
OPL interfaced with advanced Psion Series 3 features by means of operating system CALLs, but in the later Psion Series 5mx this was changed to a so-called 'OPX' library, stored in the system ROM. 'OPX' libraries were also made available for the Nokia 9210, Nokia 9300 and Nokia 9500 Communicators, adding OPXs routines for handling SMS and managing Bluetooth communication. Other OPL features include those with a letter 'g' at the beginning, for graphical functions; those with a letter 'm', for menus; and those with a letter 'd', for dialogs.
