How can I override a property ?

Test code:
----------------------------
class A
{
    @property bool foo { return false; }
    void myFunc() { ... }
}

class B : A
{
    override bool foo { return true; } // error
    override void myFunc() { ... }
}
----------------------------
Output error:
function B.foo return type inference is not supported if may override base class function.

Any ideas ?

On Thursday, 14 April 2016 at 20:21:38 UTC, Lucien wrote:
> How can I override a property ?
>
> Test code:
> ----------------------------
> class A
> {
>     @property bool foo { return false; }
>     void myFunc() { ... }
> }
>
> class B : A
> {
>     override bool foo { return true; } // error
>     override void myFunc() { ... }
> }
> ----------------------------
> Output error:
> function B.foo return type inference is not supported if may override base class function.
>
> Any ideas ?


try

class A
{
    @property bool foo() { return false; }
    void myFunc() { ... }
}

class B : A
{
    override @property bool foo() { return true; } // error
    override void myFunc() { ... }
}

On 4/14/16 4:21 PM, Lucien wrote:
> How can I override a property ?
>
> Test code:
> ----------------------------
> class A
> {
>      @property bool foo { return false; }

This isn't valid, you need parentheses for foo. This doesn't compile does it?

>      void myFunc() { ... }
> }
>
> class B : A
> {
>      override bool foo { return true; } // error

Same thing here.

>      override void myFunc() { ... }
> }
> ----------------------------
> Output error:
> function B.foo return type inference is not supported if may override
> base class function.

This has to do with type inference. Did you not specify bool in your original?

If I put parens on both foo, then it compiles for me.

-Steve

On Thursday, 14 April 2016 at 20:39:50 UTC, Steven Schveighoffer wrote:
> On 4/14/16 4:21 PM, Lucien wrote:
>> How can I override a property ?
>>
>> Test code:
>> ----------------------------
>> class A
>> {
>>      @property bool foo { return false; }
>
> This isn't valid, you need parentheses for foo. This doesn't compile does it?
>
>>      void myFunc() { ... }
>> }
>>
>> class B : A
>> {
>>      override bool foo { return true; } // error
>
> Same thing here.
>
>>      override void myFunc() { ... }
>> }
>> ----------------------------
>> Output error:
>> function B.foo return type inference is not supported if may override
>> base class function.
>
> This has to do with type inference. Did you not specify bool in your original?
>
> If I put parens on both foo, then it compiles for me.
>
> -Steve

You're right.
In fact it didn't work because I did:

----------------------------
class A
{
    @property foo() { return false; }
    void myFunc() {  }
}

class B : A
{
    override @property foo() { return true; } // error
    override void myFunc() {  }
}
----------------------------

When I remove the bool, the program compile but show the error when overriding.
Is it a bug ?

On 4/14/16 4:54 PM, Lucien wrote:
>
> You're right.
> In fact it didn't work because I did:
>
> ----------------------------
> class A
> {
>      @property foo() { return false; }
>      void myFunc() {  }
> }
>
> class B : A
> {
>      override @property foo() { return true; } // error
>      override void myFunc() {  }
> }
> ----------------------------
>
> When I remove the bool, the program compile but show the error when
> overriding.
> Is it a bug ?

Hm... I don't know. the error specifically says it's not supported. But it seems to me odd that it wouldn't. What is the harm in letting the derived function use inferred return type?

I don't know the reasoning behind the error condition, so I can say it's definitely not a bug, but I don't know why it's this way. Perhaps there's some situation that I'm not thinking of.

-Steve