How to use system'collections?

[ghost]

I don't want to sound harsh, but the API reference is practically useless.

Take the ArrayList reference, for example: https://elena-lang.github.io/api/system-collections.html#ArrayList

One thing you notice immediately: it's way too short! There can't possibly be so few methods available. Compare it to the Java or .NET API references and you'll see how abnormal this is. There's not even an add method. How am I supposed to add new elements? By index, like a regular array? Why is it so bare-metal? I just don't get it.

Anyway, I tried adding an element using the index, and the compiler accepted it. But then console.printLine refused to print the actual value (which is a real number). I tried using as:real, but it threw an error saying it doesn't know how to perform the type cast. It's driving me crazy!

And to make things worse, I can't find a single example of how to use system'collections in examples60!

I can't say whether the extensions feature is good or not, but it makes browsing the API reference really difficult. What I expect to be there is actually defined somewhere else. I have to blindly search through the API reference, and only with luck can I find what I'm looking for!

console actually has both .PrintLine and .printLine, but .printLine is the one I should be using. I wanted to understand the difference between them, so I checked the API reference: https://elena-lang.github.io/api/system.html#console. But guess what? There's no mention of either .PrintLine or .printLine. Where am I supposed to find them? Where could they be defined? I expected them to be in extensions, but they're not there either!

I've never written such a long rant before. This whole experience was exhausting, confusing, and deeply frustrating. I spent an entire afternoon and got absolutely nothing out of it.

[arakov]

There is a method to add an element to the array. You just need to look at the methods:

As I tried to explain it many times, please always provide the code snippets.

As for collections there are plenty examples how to work with them. More than 200 - https://rosettacode.org/wiki/Category:Elena

There is no method PrintLine at all. The general principle is to have methods in lower cases.

printLine is an extension. So to look at it you have to take a look there: https://elena-lang.github.io/api/extensions.html#Object

The general idea is that printLine is polymorphic and can be used with different objects.

And about frustration. You could just asked me how to do it and I would help with it.

So it would be much better instead of rants, help me with writing tutorials for example

[arakov]

And from my experience, it is perfectly normal to spend many days in frustration looking for the solution. In fact it is a part of the job. This is how you learn

[arakov]

You can look at the example how to print an element: examples60\rosetta\arrays\

There are plenty of ways how to work with collections. You can work with them like with arrays:

auto list := new ArrayList();
list.append(1).append(2).append(3);

for(int i := 0; i < list.Length; i++) {
   Console.printLine(list[i])
};

Or as with an enumarable:

list.forEach::(item)
{
    Console.printLine(item)
};

Or

foreach(var item; in list) {
    Console.printLine(item)
};

[ghost]

I don't actually run a grep to find all source files that have import system'collections;. As you can clearly see, the names of the examples indicate that they are about normal arrays. There is no place in the name has collections nor arraylist.

[arakov]

I don't know how you searched it but there are 18 source files where system'collections is used

You could save you a lot of time if you just asked me. ArrayList is not the best way to store numbers. The correct one (similar to C# for example) is template List<real>

In most cases the difference between Array and List / ArrayList is not important.

[ghost]

Do you think this is a good warning?

warning 407: Message 'PrintLine' does not handled by the object

What does this warning mean? I'm having difficulty interpreting it. The existence of the message should be binary — it either exists or it doesn't. The phrase 'not handled by the object' is ambiguous. Does it imply the object lacks a method to process the message, or that the message is invalid for this object type?

[arakov]

Because it is not binary. Once again it is not a statically typed language.

But I don't get what is your problem. If you think the message is ambiguous you create an issue and suggest your message.

[ghost]

By the way, sometimes I see console in code, and other times I see Console. I see that Console has methods like .writeLine and .readChar. Where can I find API references for these?

[arakov]

console is obsolete name. To make it consistent, all symbols / classes start with a capital character.

The description is https://elena-lang.github.io/api/system.html#Console

[ghost]

Take the ArrayList reference: https://elena-lang.github.io/api/system-collections.html#ArrayList

It mentions a method named allocate, but doesn't explain what the method actually does.

I assumed it was meant to preallocate memory for performance reasons, so I tried calling arr.allocate(n). No luck — I got an error saying the allocate message doesn't exist!

There's also another method called load. The names are as vague as they come, and I have no idea what either method is supposed to do.

[ghost]

More context: I know that allocate is a custom constructor. So I tried: auto arr := ArrayList.allocate(n);. The compiler accepted. But only to throw Nil reference exception to my face at runtime. Why?

This was before I deliberately tried to create it first then call allocate later like I have previously mentioned above.

BTW, auto arr := new ArrayList.allocate(n); will not compile, with a very funny error message:

error 184: A constructor is not defined for the class

How should I interpret it? The class ArrayList has no constructors? No. It has many constructors!

I know I should interpret it as there is no suitable constructor to be used. But I can't help laughing at this error message!

[arakov]

Once again., If you find it not very informative - create an issue.

I really don't understand what you are trying to achieve here. My advice - calm down

[ghost]

My opinion about the API reference remains unchanged: it's practically useless. It's just a table listing classes and methods, but it doesn't include any descriptions of what those classes and methods actually do. Could you put a bit more care into it so it becomes something genuinely useful? You're the only one who can — I can't help. I'm not the one who wrote the code.

[arakov]

You are the one who come here and start attacking me. I put enough efforts trying to be polite with you so far.

Documentations is really lacking, I admit it. But anyone can help. And you do not need to look into C++ code. You just look at the source code and in most cases it is very clear what the method is doing.

But of course it is much easy to come here and laugh. Very useful indeed.

[ghost]

I have something to talk about the Programmer Manual, too. It doesn't say anything about setters and getters. I tried to access a field on an instantiated object: myobj.fieldname. Nope. The compiler thinks fieldname is a message and not a field! I tried to make the field public (based on my former knowledge of Java and C#). But the compiler said this is not allowed! Finally, I had to come up with a messy get method to get things done. Why don't you write anything about that in the Programmer Manual?

You said I should help writing tutorials — but I need to actually understand the language first. How am I supposed to learn it properly? By digging through the C++ source code? Oh man...

[arakov]

No, first of all, you start a polite dialog. About properties. you can take a look here - https://github.com/ELENA-LANG/elena-lang/wiki/ELENA-Programming-Manual#properties. The first thing it says

In ELENA class fields cannot be directly accessed outside their classes.

I'm starting to get tired. Don't waste my time with your emotions. Once again calm donw

[ghost]

I calmed down and decided to go with Objective C. No more hiccups.

[arakov]

Good for you. I'm surprised it took you so long to choose between commercial product and hobbyist project.

But I'm sure even there you will be able to find someone to harass, Good luck