article

Add Scripting to your apps!

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Submitted on: 1/27/2015 4:13:00 AM
By: IRBMe (from psc cd)  
Level: Beginner
User Rating: By 5 Users
Compatibility: VB 4.0 (32-bit), VB 5.0, VB 6.0, VB Script
Views: 723
 
     Every wanted to allow users to control certain aspects of your program...to make you programmes shorter and easier...this shows you how to add scripting to your apps using the VBScript control. It mostly focuses on the purpose and usage of it.

 
				






I’m can’t be bothered doing a long intro so I’ll cut it short
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I’m can’t be bothered doing a long intro so I’ll cut it short. This will hopefully show you how to add scripting to your programs, what kind of programs you can add scripting to, and some possible uses of scripting.

 

The structured programming model is one which should all be familiar with. Even in Event-Driven languages like VB, we still use A LOT of structured programming.

Structured programming is the type that goes like this:

 

 

INPUT ======> PROCESS ======> OUTPUT

 

 

The input is what the user does. Whether they type a certain thing, click a button, move the mouse…whatever

 

The output is what gets displayed on screen to your users.

 

The process is the part we are interested in, this is where most of your programming effort is focused. This is the part where you make decisions, call functions, carry out certain tasks, and produce a result (not always the case though) which will be carried on to the output part.

 

But, imagine if your users could control certain parts of your process!

 

Lets say you are writing a chatter bot…it has to be able to be added to without re-compiling. You could use databases of phrases, or text files or whatever. However by themselves, they are very limited in producing the user’s desired results.

 

So you search around a bit and you think “Hey, seems that what my program needs is its own scripting language” but who wants to spend weeks trying to write a good scripting engine? I’ve tried and believe me, there is no more extensive usage of the “split” “join” “mid” “left” “right” “instr” “instrrev” and “len” functions but to name a few. Trust me here when I say even the best written code is NOT pretty! And it’s a nightmare to debug. “Well that’s that option out of the window. Back to text files?” I hear you ask. And I say “NEI my hard-coding amigos! There is a better way!”.

 

We aren’t going to create our own scripting language; we are going to use “VBScript” or “Jscript”. If you have the MSScript control that is included with Visual Basic Enterprise or Professional Edition (I think) then you are in luck! The code is simple.

 

I’m going to use a real life example just to demonstrate the use of this brilliant control.

 

Now I go on IRC a lot and I like to amuse my fellow VB coders in the channels or even help then or provide useful information with my bots. For those of you who don’t know what they are, they are programs that automatically connect to a chat room and run without any user intervention. My bot replies to commands typed by users.

 

Not a single one of my commands are hard-coded into VB. Anybody who has a compiled version can write their own commands and customize them as they please, using a choice of languages! Here’s a simple one…a file called “Command:Say.VBS”

 

 

Function Say (Data)

Say = Trim(Data)

End function

 

Obviously my say command is a lot more complex that that, it trims off spaces, checks for names, can add time and date and…. it does a lot ok but moving on. This takes us back to the very beginning; you remember the Input – Process – Output part? Well, we just wrote a function that takes input, jiggles it about and does what it wants with it, then produces an output.

 

We take commands from the user, send them to this “say” script, and return the output of the function back to the user. I have many other larger and more complex scripts for my bot, each dealing with its own error handling, string handling, checking and everything. Some are over 100 lines long.

 

That is just one extremely useful…eh…use. But there are hundreds more; you just got to use your imagination. They are extremely useful in any AI programs I can tell you that though!

 

Now, how to actually implement this? Well first you add the Script control by right clicking somewhere on your toolbox and clicking Components. Now find it and add it and draw a copy on your form, mine is called “Script”.

 

First thing we have to do is add our code….

 

Script.AddCode “Function Say(Data)” & vbcrlf & “Say = Trim(Data)” vbcrlf & “End Function”

 

Then we can keep adding functions by using the “AddCode” method. Note: the previous code is not overwritten.

 

We could easily add the code from files (They don’t have to be named .vbs or .js or whatever, they can be .dat, .txt .script, whatever you want)

 

So how do we input/output data from the function…like so:

 

Output = Script.Run(ProcedureName,Param1,Param2, Param3,…..)

 

You can add as many or as little parameters as your function requires after the “FunctionName” parameter. It is a ParamArray. Example:

 

IRC.SendChat Script.Run(“Say”,ChatMessage)

 

And that works nicely for my IRC bots ;)

Also a good function to know is the EVAL method. I use it to impress my buds on IRC. Just imagine:

 

“Hey bot, whats sin(1 + 4) * cos(-sin(cos(100)) + 100 / 1000) – 10^2”

“That’s easy, the answer is…<ANSWER HERE>”

 

Only it gives the answer of course :-P

It looks quite impressive. But it can be used in programs like calculators, or graph plotters (I have an example of one of those here on PSC)

 

It takes a string expression and attempts to solve it basically. Just experiment to see what it can and can’t do!

 

Ok, I hope this is a clear tutorial on how to add scripting to your programs. If you read it at all, please feel free to leave a comment J I like to feel appreciated. Hehe

 

Later all. And for those who I talk to on IRC (V*r*sF*e*, D*A*K and all the others, you know who you are, but others don’t. Nice privacy thing there J) I’ll have my new APIBot up soon!

 

 

 

 


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