So that classes can share some of their variables but not others in a module.

IE.

class A
{
internal int A; //This is shared in the module
private int B; // But not this.
}

No need to reintroduce the "Friend" feature from cpp.

On Sunday, 21 October 2018 at 03:17:23 UTC, 12345swordy wrote:
> So that classes can share some of their variables but not others in a module.
>
> IE.
>
> class A
> {
> internal int A; //This is shared in the module
> private int B; // But not this.
> }
>
> No need to reintroduce the "Friend" feature from cpp.

This is by design; the D way of dealing with this would be to split the module into a package with multiple modules. The A class would be in its own module, and use `package` where you used `internal` so that other modules in the same package can have access to it.
Using a package.d package module (https://dlang.org/spec/module.html#package-module), you can still use the multiple modules just as if they were a single module.

Instead of a source tree like this:

source
|
+-some
  |
  +-thing.d

You'd end up with a source tree like this:

source
|
+-some
  |
  +-thing
    |
    +-package.d
    |
    +-a.d
    |
    +-rest_of_the_stuff.d

Where package.d publicly imports a.d and rest_of_the_stuff.d, so `import some.thing` would still work.

On Sunday, 21 October 2018 at 03:17:23 UTC, 12345swordy wrote:
> So that classes can share some of their variables but not others in a module.
>
> IE.
>
> class A
> {
> internal int A; //This is shared in the module
> private int B; // But not this.
> }
>
> No need to reintroduce the "Friend" feature from cpp.

I partially agree because Object Pascal uses `strict private` for this. IIRC they needed at some point to make this for their Objective-C compatibility. I find it occasionally useful for example to enforce the usage of the getters method over their matching fields (if they do lazy update, lazy init, or such things). So far in D the way to do this is to put the stuff that has to be strictly private (or internal if you prefer) in a dedicated module.

This suggestion comes semi-regularly on the forum and last time it did, the whole topic got very unfriendly so while i partially agree i have to say that i don't really care. It's a small sympathetic feature, but i can live without.

Baz.

On Sunday, 21 October 2018 at 03:17:23 UTC, 12345swordy wrote:
> So that classes can share some of their variables but not others in a module.
>
> IE.
>
> class A
> {
> internal int A; //This is shared in the module
> private int B; // But not this.
> }
>
> No need to reintroduce the "Friend" feature from cpp.

I feel like if this is a problem your Module has too much in it and you should refactor it into more than 1 module. If you need to protect a module from itself then I feel like there is too much in it, essentially.

On Sunday, 21 October 2018 at 08:40:36 UTC, Laurent Tréguier wrote:
> On Sunday, 21 October 2018 at 03:17:23 UTC, 12345swordy wrote:
>> So that classes can share some of their variables but not others in a module.
>>
>> IE.
>>
>> class A
>> {
>> internal int A; //This is shared in the module
>> private int B; // But not this.
>> }
>>
>> No need to reintroduce the "Friend" feature from cpp.
>
> This is by design; the D way of dealing with this would be to split the module into a package with multiple modules. The A class would be in its own module, and use `package` where you used `internal` so that other modules in the same package can have access to it.
> Using a package.d package module (https://dlang.org/spec/module.html#package-module), you can still use the multiple modules just as if they were a single module.
>
> Instead of a source tree like this:
>
> source
> |
> +-some
>   |
>   +-thing.d
>
> You'd end up with a source tree like this:
>
> source
> |
> +-some
>   |
>   +-thing
>     |
>     +-package.d
>     |
>     +-a.d
>     |
>     +-rest_of_the_stuff.d
>
> Where package.d publicly imports a.d and rest_of_the_stuff.d, so `import some.thing` would still work.
I know what the current design is!! You have zero tools in regarding to allowing class to share certain variables but not others in the same module! Create a module for every class is taking all or nothing approach, when there is a reasonable middle ground.
Your package solution just make things more unnecessarily complicated then warranted

On Sun, 21 Oct 2018 08:40:36 +0000, Laurent Tréguier wrote:
> This is by design; the D way of dealing with this would be to split the module into a package with multiple modules.

This is often a usable way of doing things, but sometimes not so much. If you're writing a script for use with dub --single or rdmd, you lose a lot of convenience if you use multiple files. It might also take a lot of time to split things up once static constructors get involved.

On Saturday, October 20, 2018 9:17:23 PM MDT 12345swordy via Digitalmars-d wrote:
> So that classes can share some of their variables but not others in a module.
>
> IE.
>
> class A
> {
> internal int A; //This is shared in the module
> private int B; // But not this.
> }
>
> No need to reintroduce the "Friend" feature from cpp.

Well, if you feel strongly enough about it, you can always create a DIP to try to change things, but I think that I can quite safely say that you have pretty much no chance of it getting accepted. Walter has been quite clear on this topic when it has been discussed previously (and there was a major discussion on it not very long ago). It is very much on purpose that access is controlled at the module level, and if your module is large enough that it is actually causing problems for a class or struct to not be able to disallow access of its members to other symbols in the module, then the module is too large, and the class should be put in a separate module. We already have full control of who can access the members of a class or struct by controlling which module or package its in and what else is in that module or package with it. If you want greater control without splitting up your modules more (at least as far as importing goes), you can always take advantage of public imports to split the code itself into more modules while making it possible to get all of the symbols with a single import statement.

Certainly, if we had internal or friend or other mechanisms for more fine-grained control without doing it at the module-level, it would eliminate the need to put code into separate modules in some cases, but it would also complicate the language, and what we have works quite well in general.

If you don't like the fact that member access is done at the module level, then I'm sorry, but overall, this really seems to be a philosphical complaint and not a practical one, and Walter has made his stance on it very clear. Based on what he's said previously, you would need very strong, practical arguments for why it's causing actual bugs in programs and why the current approach is not cutting it to stand any chance of convincing Walter. And honestly, I have never seen anyone come up with an argument that was particularly good in that regard. It mostly seems to come down to folks simply objecting to the idea that anything inside a module would have access to a class' private members rather than that it's actually caused bugs. In practice, it's usually either actually useful, or it doesn't matter.

Either way, simply making post stating that you think that we should have the feature isn't going to get you anywhere. If you want it, you'll need to find a way to convince Walter.

- Jonathan M Davis

On Sunday, 21 October 2018 at 17:09:05 UTC, 12345swordy wrote:
> I know what the current design is!! You have zero tools in regarding to allowing class to share certain variables but not others in the same module! Create a module for every class is taking all or nothing approach, when there is a reasonable middle ground.
> Your package solution just make things more unnecessarily complicated then warranted

It's not "my" solution. It's D's solution. I perfectly understand why you'd want this and I would probably make use of a private/internal difference myself if it was available.

If you already know about this solution however, I don't even know why you're starting this thread; since changing the behavior of private would be a major language change breaking tons of existing codebases, plus it would require adding yet another keyword.

Given that this conversation has happened before and things haven't changed, I'm very doubtful that it could happen at any point in time, sadly.

On Sunday, 21 October 2018 at 17:48:08 UTC, Neia Neutuladh wrote:
> On Sun, 21 Oct 2018 08:40:36 +0000, Laurent Tréguier wrote:
>> This is by design; the D way of dealing with this would be to split the module into a package with multiple modules.
>
> This is often a usable way of doing things, but sometimes not so much. If you're writing a script for use with dub --single or rdmd, you lose a lot of convenience if you use multiple files. It might also take a lot of time to split things up once static constructors get involved.

As far as single file scripts go, I don't think something like 100% perfect encapsulation is always required. A single file script is usually a quick way to do a specific thing once or twice, and not a persistent project demanding the best code quality.

On Sunday, 21 October 2018 at 19:53:35 UTC, Jonathan M Davis wrote:
> On Saturday, October 20, 2018 9:17:23 PM MDT 12345swordy via Digitalmars-d wrote:
>> So that classes can share some of their variables but not others in a module.
>>
>> IE.
>>
>> class A
>> {
>> internal int A; //This is shared in the module
>> private int B; // But not this.
>> }
>>
>> No need to reintroduce the "Friend" feature from cpp.
>
> Well, if you feel strongly enough about it, you can always create a DIP to try to change things, but I think that I can quite safely say that you have pretty much no chance of it getting accepted. Walter has been quite clear on this topic when it has been discussed previously (and there was a major discussion on it not very long ago). It is very much on purpose that access is controlled at the module level, and if your module is large enough that it is actually causing problems for a class or struct to not be able to disallow access of its members to other symbols in the module, then the module is too large, and the class should be put in a separate module. We already have full control of who can access the members of a class or struct by controlling which module or package its in and what else is in that module or package with it. If you want greater control without splitting up your modules more (at least as far as importing goes), you can always take advantage of public imports to split the code itself into more modules while making it possible to get all of the symbols with a single import statement.
>
> Certainly, if we had internal or friend or other mechanisms for more fine-grained control without doing it at the module-level, it would eliminate the need to put code into separate modules in some cases, but it would also complicate the language, and what we have works quite well in general.
>
> If you don't like the fact that member access is done at the module level, then I'm sorry, but overall, this really seems to be a philosphical complaint and not a practical one, and Walter has made his stance on it very clear. Based on what he's said previously, you would need very strong, practical arguments for why it's causing actual bugs in programs and why the current approach is not cutting it to stand any chance of convincing Walter. And honestly, I have never seen anyone come up with an argument that was particularly good in that regard. It mostly seems to come down to folks simply objecting to the idea that anything inside a module would have access to a class' private members rather than that it's actually caused bugs. In practice, it's usually either actually useful, or it doesn't matter.
>
> Either way, simply making post stating that you think that we should have the feature isn't going to get you anywhere. If you want it, you'll need to find a way to convince Walter.
>
> - Jonathan M Davis
I do plan to write a DIP on this, no question about it. However walter have been shown to change his mind unexpectedly. (Remember the "mangle symbol only" discussion that manu had argue in favor of, which we all thought he sternly opposed to, only to changed his mind at the last minute, when a pull request shown up?)

Yes I am aware of the previous discussion regarding this. How can I forget about it as that guy who complain about it resort to imposter other people including me.

https://forum.dlang.org/thread/vpxoidaqfbfrnnsepzmn@forum.dlang.org?page=1


However that guy didn't property explain why this was an issue. The issue is encapsulation and the traditional get and set functions for security checking and value checking, etc, before setting the value, retrieving the value and after setting the value. Programmers such my self sometimes find it easier to maintain classes if they are put in the same file, rather than in each own file.
The "package" solution brought up by another user risk the possibility of making things more complicated and harder to maintain than it should be, when working with code that is considerably small spread across multiple files.

I have two solutions in mind:
A.)Introduce the keyword "strict" for the other keywords private and protected  only class and structs to prevent being accessed from outside the class in the same module by accident.
Example:
class A
{
strict private int x;// This can't be shared in module
strict protected int y; //ditto
private int x; //This can be shared in module
protected int y; //ditto
}
B.)Get rid of the "one module per file" restriction by introducing optional module scoping to allow multiple modules in a file to allow easy package creation for code that is consider to be small without having to maintain multiple files.
Module C;
Module A // Module A in the C package
{

}
module B // AKA B.A
{

}

-Alex