Scripters cove

[TGHC]

WD Svengali, Eric Walsh is also doing a fine job updating old OXP's, so I guess you need to pm each other, to avoid duplication, or alternatively publish a list of candidate OXP's, and who is working on them, it may encourage others to join in, I would if I could, but I don't know how to.

[Svengali]

WD Svengali, Eric Walsh is also doing a fine job updating old OXP's, so I guess you need to pm each other, to avoid duplication, or alternatively publish a list of candidate OXP's, and who is working on them, it may encourage others to join in, I would if I could, but I don't know how to.

You COULD join too. As a experienced senior member you know which OXP is abandoned and which is not. You can send this list to me and I'll contact Eric.

The next step:

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// Checks if the licence for a special equipment is expired. If so it removes the equipment and returns "expired" else "ok"
function CheckLicence(licencetilldate, specialdevice)
{
	if (clock.days >= parseInt(licencetilldate))
	{
		player.removeEquipment(specialdevice);
		player.commsMessage("The licence for your "+specialdevice.slice(3,specialdevice.length)+" is expired. Buy a new one at your local dealer.");
		return ("expired");
	}
	else
	{
		return ("ok");
	}
}

It is called by:

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if (CheckLicence(missionVariables.hyperradio_last, "EQ_HYPER_RADIO") == "ok")
	{ do something }
else
	{ do something }

But before the time has to be set:

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missionVariables.hyperradio_last = String(Math.floor(20 + (clock.days)));

[TGHC]

I'll have a go at it, there are at first glance about 160 OXP's on the Wiki.
It's my Financial year end tomorrow so just a bit stuffed with time at the moment but will get on with it PDQ

[Eric Walch]

And a second thing. Yesterday I've tested to split the hyperradio.OXP into two OXPs. One with a function library and one with the ingame-used things. It works fine - so maybe we should also make a general OXP-Function-Library that can be used by all scripters. That would be a great improvement for scripting new OXPs.

Yes, that is also one of the advantages of JS: you can define functions. And functions that are very useful for general use can be collected into one big library. This way not everybody needs to re-invent the wheel, but just can call a useful function from this library.

I think it is important to have several good examples of scripting to start learning it. It will help if the first larger JS script will see daylight. In the past I mastered (and forgotten) a lot of program languages. I remember that only the start is difficult, but one needs examples in one place. Now they are scattered throughout this board.

[Svengali]

Yes, that is also one of the advantages of JS: you can define functions. And functions that are very useful for general use can be collected into one big library. This way not everybody needs to re-invent the wheel, but just can call a useful function from this library.

I think it is important to have several good examples of scripting to start learning it. It will help if the first larger JS script will see daylight. In the past I mastered (and forgotten) a lot of program languages. I remember that only the start is difficult, but one needs examples in one place. Now they are scattered throughout this board.

So here is the place for them. Lets collect these sweeties and I'll build up a function-lib, put it on a server and if it's getting bigger it will be placed on the WIKI. So if you've got an code-snippet that is generally usable (and working) post it here.

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	// This returns a random number in the range of min-max or -1
	function GetRandomA(min, max)
	{
		if(min > max) { return(-1); }
		if(min == max) { return( min );	}
		let r = parseInt( Math.random() * (max+1));
		return(r + min <= max ? r + min : r);
	}

[JensAyton]

I mentioned this in a private message, but: any function declared with the “function foo()” syntax which is not inside another function is global, that is, it is seen by all scripts. I strongly recommend placing such functions inside an object, which will act as a namespace. For example:

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SvengaliMathFuntions =
{
    GetRandomA: function(min, max)
    {
        // same code as above
    }
}

This can be used by other scripts like so:

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this.SMF = SvengaliMathsFunctions
this.randomValue = SMF.GetRandomA(1, 5)

Actually, thinking about it, it would probably be better to do it like this:

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// Library script
this.name = "svengali_math_functions_v1"
this.GetRandomA = function(min, max)
{
    // Same code as above
}

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// Client script
this.SMF = worldScripts["svengali_math_functions_v1"]
this.GetRandomA = SMF.GetRandomA
this.randomValue = GetRandomA(1, 5)

Why is this better? Well, I hope to be able to trick the JS library into putting global declarations into the current script object instead of the global object, in which case the first method will stop working.

Note also the _v1 suffix. If more than one script has the same name, only one will be findable, so new versions need to have new names. A simple way to be backwards-compatible would be for the new version to include scripts which transclude functions into the old namespace. Er, so to speak. :-)

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// svengali_math_functions_v2.js
this.name = "svengali_math_functions_v2"
this.GetRandomA = function(min, max)
{
    // Same code as above
}

this.DoSomethingElse = function()
{
    // Whatever, a new function
}

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// svengali_math_functions_v1.js
this.name = "svengali_math_functions_v1"
this.v2 = worldScripts["svengali_math_functions_v2"]

this.GetRandomA = v2.GetRandomA // Transclude function from v1

delete this.v2

[Svengali]

SvengaliMathFuntions =

Hehe, that sounds nice...
But it is not my intention to get my very own library. I'm thinking of:

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this.name           = "functionlib";
this.author         = "Oolite BB";
this.copyright      = "Creative Commons 2.0";
this.description    = "OXP Function Library";
this.version        = "1.00";

We are a community and only we all together can make the world a little bit better.

Well, I hope to be able to trick the JS library into putting global declarations into the current script object instead of the global object...

Does it mean that a script object can declare methods, functions, maybe even classes? I think I didn't get the point.

[JensAyton]

As it is, script object methods are declared using the somewhat weird syntax this.method = function(parameters) { code }. I’d like to be able to use the syntax function method(parameters) { code }, partly because it strikes me as simpler, and partly because I don’t like the fact that global declarations are the default; that sort of makes sense in a web context, but not so much in Oolite.

JavaScript 2 will add support for classes, but I don’t intend to use them in the scripting interface. The prototype-based approach is good for customizing ships and such. On the other hand, classes provide a good way to structure code, and making them available for OXP scripts to use internally would be good.

[Svengali]

...any function declared with the “function foo()” syntax which is not inside another function is global, that is, it is seen by all scripts.

That's the intention of this function library. A collection of useful things like the random number generator. Maybe the first snippets are a little bit too specific for the library.

I strongly recommend placing such functions inside an object, which will act as a namespace.

I agree that we should use the naming conventions that are already there for the legacy-scripting (unique names). Even if it would lead to some more code. That prevents us from getting trouble. And declaring an object is done within a few lines of code.

Well, I hope to be able to trick the JS library into putting global declarations into the current script object instead of the global object...

But does the 'normal' global declaration work too?

...because I don’t like the fact that global declarations are the default;

I think JS is running in an sandbox. So this couldn't be a real problem. Or do you think about conflicts between JS-OXPs? Maybe double declarations or changed methods/properties...

[LittleBear]

Does 1.70 replace a dead ship with a new one of the same role, in the same way as replacing when witching out? If so could we have a "dieWithoutReplacing" as you don't really want a mission ship respawned.

[Eric Walch]

As a result of playing with several scripts over the past week I wrote a page in the wiki how in my opinion a legacy script could get largely improved in speed performance.

Most scriptwriters are no programmers and just copy methods they see in other scripts. Over the past week I rearranged 3 old mission scripts according to these rules and re-uploaded them. Compared with the old flat structure, evaluation of this nested structure will probably use less then 10 percent of the original evaluation time.

The file is linked from the script.plist page and also from the index pages.

Structured_Legacy_Scripts

Any comment on this is welcome as this is only one opinion on writing.

With this document in hand I also looked at my own UPS courier and also there nested some conditions deeper to minimise the checks at idle time.

[Svengali]

Very good work, Eric.

Easy to understand - even for non-native english speakers.
I think you should add a link to your MOP, because any new mission-script should include your mission_offering check.

[Eric Walch]

even for non-native english speakers.

Hmm.. as non-native English speaker I am not capable of creating such text as I than would not understand it myself. Or not.

I was afraid it was to complex written, on the other hand it is only mend for scripters and from those I may expect a certain knowledge that they understand it.

[Svengali]

I was afraid it was to complex written, on the other hand it is only mend for scripters
and from those I may expect a certain knowledge that they understand it.

I don't think that it is to complex. Your article gives us some background information that is very useful to understand what Oolite is doing. So it helps every scripter to understand why and how Oolite reacts. I know that it's only the first step in understanding, but it's a good motivation to start this process.

[Svengali]

Ok. Forget my last posts about the function lib.

...to trick the JS library into putting global declarations into the current script object...

After reading some more docs this was the result (without using literals). Would this work after lowering the top-level?
Library:

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this.name           = "BBFL";	// Is this already a 'namespace'-object?
this.author         = "Oolite BB";
this.copyright      = "Creative Commons 2.0";
this.description    = "OXP Function Library";
this.version        = "1.00";
// Declare an empty object as namespace AND global
var BBFL_Math = {};
    // Then declare the members (methods, properties) as public
    BBFL_Math.GetRandomA = function(min, max)
    {
           // code
    }
    BBFL_Math.DeclareNextMember = function(x, y, z)
    {
          // code
    }
// Then the next namespace, maybe Vector or...
var BBFL_Vector = {};...

I've used a prefix (BBFL_) for all lib-objects, so it's clear for an scripter that this is related to this Function Library.
This could be used in the client script:

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BBFL_Math.GetRandomA(1, 7);

Ahruman, you have suggested to use a suffix (_v1, _v2,...). I like this idea to be backward compatible, but is this really necessary. There is already a this.version = "1.00". So maybe a check for the correct version could (and should) be realised.