I am trying to make a tactical role-playing game which I am likely to open-source. Right now the code is very simple, with only 3 files each containing a class with the same name.

The files are Map.d, Tile.d, and Unit.d. Each of these files contains an import line to access one of the others. I got the following errors when trying to compile all 3 files with DMD, and the same errors after switching to DUB.

source/Unit.d(6,17): Error: import `Unit.Map` is used as a type
source/Unit.d(16,5): Error: import `Unit.Map` is used as a type
source/Tile.d(9,15): Error: import `Tile.Unit` is used as a type
source/Map.d(6,22): Error: import `Map.Tile` is used as a type
source/Map.d(19,11): Error: import `Map.Tile` is used as a type

I thought that the circular chain of imports may be the problem, but removing all references to Unit in Tile.d did not fix the problem.

Here are the contents of Tile.d:

import Unit;

class Tile
{
	private bool allowStand = true;
	private bool allowFly = true;
	public int stickyness = 0;
	
	public Unit* occupant;
	
	bool allowUnit(bool isFlyer) {
		if (isFlyer) return this.allowFly;
		else return this.allowStand;
	}
}

Unit.d & Map.d are longer files. Map.d begins with import Tile;, and Unit.d begins with import Map;.

Why are the errors happening? What's the problem? Why is it currentclass.importedclass instead of simply the imported class?

On Saturday, 24 February 2024 at 10:31:06 UTC, Liam McGillivray wrote:

You can't give a class the same name as the file it's in. If you do, then when you try to use it from another file, the compiler will get confused and think you're referring to the file instead of the class (that's what "import is used as a type" means).

The easiest way around this is to change the name of the file to lower case. So, for example, you could change the name of the file with the Unit class in it to unit.d, and then write import unit; to access it from your other files.

On Sunday, 25 February 2024 at 03:23:03 UTC, Paul Backus wrote:

Thank you. In PHP, I was told to put every class definition in a file of the same name (whether I like it or not).

However, I actually now have it working without having done that. Both the file name and the class name are capitalized, and it's working. However, maybe that's because they each start with a module line that makes the module name lowercase. I will keep this in mind, and maybe rename the files.

I don't know whether I should continue this topic or start a new one now that the problem mentioned in the title is fixed. I have now uploaded some of the code to a GitHub repository.

To make this game usable, I will need a library for graphics and input. I don't have any experience with making GUI programs aside from a little bit with Qt and C++.

I have considered the following libraries:

• SDL: Seems too low-level for me.
• Allegro via DAllegro5: I found some C & C++ tutorials for this one, but I don't know how I would do it with D. This one looks difficult.
• Imgui via Dimgui: While Imgui looks well-developed, the Dimgui readme links to this repository, which looks like a very old version of Imgui.
• Godot via Godot-Dlang: A well-developed game engine with an editor that may allow me to get fancier graphics without a huge amount of effort. However, the project page for Godot-Dlang gives a warning that it's unfinished. This may or may not be a problem given that this is just a hobby project. I would be happy to share any problems with the developers.
• SFML via BindBC-SFML: SFML appears to be an easier way to get 2D graphics working compared to SDL & Allegro when using C++. However, it may take more effort to use it with D.
• AE: This is a D library that provides graphics and other utilities using various C libraries. I am beginning to understand this one, as I've been looking at the provided demos. However, this one seems to SDL functions directly whenever an image is placed on-screen, which I don't understand the theory behind.

I have writing the code for the internal game logic as a library that can be used by various front-ends for graphics. This would let me experiment with different software for graphics, but it would make the code more complicated.

So far I have been attempting to get it working with AE for graphics, not using the library approach described above. I haven't committed it with git, as I have copied and pasted substantial code from the AE examples and I will need to look at the license before I share it. I have managed to get it to read a PNG using libpng, but not display it. I have had trouble with this. One of the demos uses a function s.draw for displaying an image, which isn't defined anywhere in AE, so it might be an SDL function. I don't know how it has access to it.

I chose to use D for this project because I have long wanted to learn the language, but I wonder if it's overkill for this project, given the low performance requirement. Maybe I would be better-off using a dynamic interpreted language. The benefit of D is largely for the learning experience.

On Monday, 26 February 2024 at 22:40:49 UTC, Liam McGillivray wrote:

So D is weird about this. I always recommend you use a package (i.e. module foo.bar) instead of just a module (i.e. module bar).

When you omit the module declaration, the compiler assumes the module name is the same as the file name without the path taken into account.

What happens is if you have Map as a module, and then Map as the class name, using the name Map is going to be confusing (did you mean the module or the class?)

However, if you have everything under a package, for example foo, i.e. a file foo/Map.d which contains the Map class, then when referring to Map, it can't be referring to the module, since you would have to refer to foo.Map for that. This means the class name Map by itself is unambiguous.

A whole host of problems occurs with name lookup when you don't use packages.

-Steve

On Monday, 26 February 2024 at 23:27:49 UTC, Liam McGillivray wrote:

If you are going for game development, I would recommend raylib-d (https://code.dlang.org/packages/raylib-d), which is my wrapper around the very good raylib library.

For doing GUI, raygui is supported, but I also can say I've seen some good things from fluid: https://code.dlang.org/packages/fluid

-Steve

On Tuesday, 27 February 2024 at 03:06:19 UTC, Steven Schveighoffer wrote:

Raylib looks promising. I installed it along with your Raylib-d. I managed to build the example you provided with dub, but trying to use it in it's own dub project in a separate directory isn't working. Just copying and pasting app.d from the very example you provided results in a huge wall of errors, mostly "undefined reference to [some function]".