[Tutorial] Extending Turing to include custom functions.

[Tony]

I've seen the following question too often: my version of Turing is missing Math.Distance() or the such. I have v4.0.5, others might not. That's not the point - you can extend your Turing yourself.

This is really easy.

1) Locate where your copy of Turing is installed. Mine is in C:\Program Files\Turing\
2) Follow on to Turing\Support\predefs\
3) Create a new file, for example - new_function.tu
4) Create your module and functions

Turing:

unit module Tony     export talk     function talk : string         result "words words words.."     end talk end Tony

5) Save, then open Turing\Support\predefs\Predefs.lst. Everything referenced in this file is included in your program.
6) At the very end of the file, add a reference to the module file you've created in step 3. "%oot/support/predefs/new_function.tu". Save.

Now you can use your Module.function in any program.

Turing:

put "Hello Tony, how are you doing?" put Tony.talk

Just keep in mind that those functions are stored on your local drive, not everybody else's -- so let others know of the modifications you're using when you're posting your source code.

Oh, and for those who are still looking for that elusive Math.Distance -- here are the contents of the Math. file

Turing:

%     % Calculate the distance between two points     function Distance (x1, y1, x2, y2 : real) : real         var dx : real := x1 - x2         var dy : real := y1 - y2         result sqrt (dx * dx + dy * dy)     end Distance     %     % Calculate the distance between a point and a line segment     %     function DistancePointLine (px, py, x1, y1, x2, y2 : real) : real         var lineSize : real := Distance (x1, y1, x2, y2)         if lineSize = 0 then             result Distance (px, py, x1, y1)         end if         var u : real := ((px - x1) * (x2 - x1) +             (py - y1) * (y2 - y1)) / (lineSize * lineSize)         if u < 0.0 then             result Distance (px, py, x1, y1)         elsif u > 1.0 then             result Distance (px, py, x2, y2)         else             var ix : real := x1 + u * (x2 - x1)             var iy : real := y1 + u * (y2 - y1)             result Distance (px, py, ix, iy)         end if     end DistancePointLine

[TokenHerbz]

Nice...

but i messed somthing up so ill do with out

ill go the old fation way...

Also when you **compile** a file with your custom funtions, will it work on others computers?

[Tony]

yes, compiled programs are independent of resources (as in -- one doesn't need Turing to be installed to run an .exe)

[Cervantes]

Good idea, Tony. Now, some more!
This is effectively the same as what Tony described. I have, however, expanded on where to place the new line in predefs.lst and also discussed export unqualified and pervasive.

Creating New Variable Types

Now that we know how to add procedures/functions to the Turing environment, we should take that a step further. What if you want to add your own variable type?

The one I use most frequently is called coord2D. Another good one to add is vector2D. These could be extended to 3D as well.

Adding custom data types is much the same as adding custom functions. Create a new file in Turing\Support\predefs\ called Custom_Data_Types.tu or something like that. Insert this code:

Turing:

unit module Custom_Data_Type  % Note that this needs to match the file name, except without the '.tu'         export coord2D, vector2D                 type coord2D :                 record                         x, y : real                 end record         type vector2D :                 record                         mag, ang : real  % Magnitude, Angle                 end record end Custom_Data_Type

Change the type if you wish. Add some more types if you wish. Just make sure to export them in the top line.

Save.

Open up Turing\Support\predefs\predefs.lst.
Add "%oot/support/predefs/Custom_Data_Types.tu" just after the anyclass (which is the first line). Adjust the filename (Custom_Data_Type.tu) as appropriate.
I say to put this near the top because doing this will allow you to use your custom types within the other modules. For example, I have a good many of the Mouse functions to work with coordinates rather than two seperate x and y parameters.If you want to use your custom functions in other modules, you'll need to save them near the top, not at the bottom.

You're done. Keep in mind though that you didn't make these things pervasive, or export unqualified. In other words, you will have to import them into modules/class etc., and you will have to attach the module name before the type.

To make these things export unqualified and pervasive, add a ~. and * before the type/function name. Like this:

Turing:

unit module Custom_Data_Type  % Note that this needs to match the file name, except without the '.tu'         export ~.*coord2D, ~.*vector2D                 type coord2D :                 record                         x, y : real                 end record         type vector2D :                 record                         mag, ang : real  % Magnitude, Angle                 end record end Custom_Data_Type