• Some additional examples
A mathematical graph example -- Descartes' folie
• Query time example
- The following example provides the time of day in English.
- It is a derivation of Michael Cowlishaw's QT example program.
- The example illustrates the object-oriented concept of polymorphism.
- The qt class (qt.roo) prepares the time of day, and sends it to an abstract emitter class.
- Actual emitter class derivatives can present the time using various alternatives.
- One emitter might use a scrolling HTML marquee, another might use a pop-up message box, while yet another may actually use an audio converter to speak the time.
qt.roo
/* qt.roo This is the supporting QT class file for the 'query time' example program from TRL-2 p172 which tells the current time in English. */ local out -- the output text destination local specificTime -- a specific time to display initialize : method parse arg out, specificTime -- set local variables from parameters -- ensure output destination is an instance if \ datatype( out, 'Instance' ) then do ^^ console ~ writeLine( 'The parameter for QT.ROO should be an output destination object instance' ) return 'The parameter for QT.ROO should be an output destination object instance' end return '' settime : method specificTime = arg(1) -- prepare to display a specific time return now telltime : method out ~ writeCharacters( "It's" ) -- start output phrase if specificTime = '' then now = time() -- show current time else now = specificTime -- show specific time -- prepare nearby time clauses near = { , '' , , ' just gone' , , ' just after' , , ' nearly' , , ' almost' } -- get hour, minute, and second parse var now hour ':' min ':' sec -- round minutes if sec > 29 then min = min+1 -- determine REMAINDER of minutes divided by 5 -- emit 'near' phrase out ~ writeCharacters( near[ 1 + ( min // 5 ) ] ) -- round hour if min > 32 then hour = hour + 1 -- increment minutes by nearby interval min = min + 2 -- show exactly noon or midnight if hour // 12 = 0 & min // 60 <= 4 then do if hour=12 then out ~ writeCharacters( 'Noon' ) else out ~ writeCharacters( 'Midnight' ) return '' end -- reduce minutes to 5 minute interval base min = min - ( min // 5 ) if hour > 12 then hour = hour - 12 -- reduce PM times by 12 hours else if hour = 0 then hour = 12 -- 0 hour: is 12 to 1 am -- prepare 5 minute interval clauses roundedMinute = , { , '' , , 'five past' , , 'ten past' , , 'a quarter past' , , 'twenty past' , , 'twenty-five past' , , 'half past' , , 'twenty-five to' , , 'twenty to' , , 'a quarter to' , , 'ten to' , , 'five to' , , '' } -- emit 'rounded' phrase out ~ writeCharacters( ' 'strip( roundedMinute[ 1 + ( min / 5 ) ], 'T' ) ) -- hour numbers hourNumbers = { 'one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine', 'ten', 'eleven', 'twelve' } out ~ writeCharacters( ' 'hourNumbers[ hour ] ) -- add current hour if 0 = ( min // 60 ) then out ~ writeCharacters( " o'clock" ) -- it's exactly a specific hour clause -- done ! return ^ self -- return 'qt' instance reference