Hello,

im tring to add nothrow keyword in my code, but compilation fails :

function 'object.opEquals' is not nothrow


its a simple comparison between 2 objects. How to make opEquals nothrow ?

thanks

On Thursday, 20 July 2017 at 14:38:03 UTC, Aldo wrote:
> Hello,
>
> im tring to add nothrow keyword in my code, but compilation fails :
>
> function 'object.opEquals' is not nothrow
>
>
> its a simple comparison between 2 objects. How to make opEquals nothrow ?
>
> thanks

Could you show some code.

On 7/20/17 10:38 AM, Aldo wrote:
> Hello,
> 
> im tring to add nothrow keyword in my code, but compilation fails :
> 
> function 'object.opEquals' is not nothrow
> 
> 
> its a simple comparison between 2 objects. How to make opEquals nothrow ?

You can't. Object.opEquals is not nothrow, so object.opEquals is not nothrow (note the former is the virtual member function, the latter is a global function which is what the compiler actually calls).

It is a legacy limitation. Until we get rid of all the Object base methods for things like opEquals and toHash, we will not be able to fix this.

-Steve

On Thursday, 20 July 2017 at 14:59:50 UTC, Steven Schveighoffer wrote:
> On 7/20/17 10:38 AM, Aldo wrote:
>> Hello,
>> 
>> im tring to add nothrow keyword in my code, but compilation fails :
>> 
>> function 'object.opEquals' is not nothrow
>> 
>> 
>> its a simple comparison between 2 objects. How to make opEquals nothrow ?
>
> You can't. Object.opEquals is not nothrow, so object.opEquals is not nothrow (note the former is the virtual member function, the latter is a global function which is what the compiler actually calls).
>
> It is a legacy limitation. Until we get rid of all the Object base methods for things like opEquals and toHash, we will not be able to fix this.
>
> -Steve

Im using DerelictGLFW3, to process events im doing this :

glfwSetMouseButtonCallback(window, &onMouseClick);

onMouseClick function must be nothrow.

But now I can't do anything in this function because I can't convert my code to nothrow.

Can I put a try catch in the body ?

extern(C) nothrow
{
    void onMouseClick(GLFWwindow* window, int button, int action, int d)
    {
       try
       {
           // my code
       }
       catch
       {

       }
    }
}

it seems its working but what about performances ?

thanks

On 7/20/17 11:10 AM, Aldo wrote:
> On Thursday, 20 July 2017 at 14:59:50 UTC, Steven Schveighoffer wrote:
>> On 7/20/17 10:38 AM, Aldo wrote:
>>> Hello,
>>>
>>> im tring to add nothrow keyword in my code, but compilation fails :
>>>
>>> function 'object.opEquals' is not nothrow
>>>
>>>
>>> its a simple comparison between 2 objects. How to make opEquals nothrow ?
>>
>> You can't. Object.opEquals is not nothrow, so object.opEquals is not nothrow (note the former is the virtual member function, the latter is a global function which is what the compiler actually calls).
>>
>> It is a legacy limitation. Until we get rid of all the Object base methods for things like opEquals and toHash, we will not be able to fix this.
>>
> 
> Im using DerelictGLFW3, to process events im doing this :
> 
> glfwSetMouseButtonCallback(window, &onMouseClick);
> 
> onMouseClick function must be nothrow.
> 
> But now I can't do anything in this function because I can't convert my code to nothrow.
> 
> Can I put a try catch in the body ?

Yes.

> 
> extern(C) nothrow
> {
>      void onMouseClick(GLFWwindow* window, int button, int action, int d)
>      {
>         try
>         {
>             // my code
>         }
>         catch
>         {
> 
>         }
>      }
> }
> 
> it seems its working but what about performances ?

As long as you don't have any code that throws, it should be pretty close to optimal.

-Steve

On Thursday, 20 July 2017 at 15:10:24 UTC, Aldo wrote:
> extern(C) nothrow
> {
>     void onMouseClick(GLFWwindow* window, int button, int action, int d)
>     {
>        try
>        {
>            // my code
>        }
>        catch
>        {
>
>        }
>     }
> }

Tangent but an easy way of nothrowing:

extern(C) nothrow
{
    void onMouseClick(GLFWwindow* window, int button, int action, int d)
    {
        scope(failure) return;

        // my throwing code
    }
}

or scope(failure) return -1; if working with error codes.

On Thursday, 20 July 2017 at 15:10:24 UTC, Aldo wrote:
> On Thursday, 20 July 2017 at 14:59:50 UTC, Steven Schveighoffer wrote:
>> On 7/20/17 10:38 AM, Aldo wrote:
>>> Hello,
>>> 
>>> im tring to add nothrow keyword in my code, but compilation fails :
>>> 
>>> function 'object.opEquals' is not nothrow
>>> 
>>> 
>>> its a simple comparison between 2 objects. How to make opEquals nothrow ?
>>
>> You can't. Object.opEquals is not nothrow, so object.opEquals is not nothrow (note the former is the virtual member function, the latter is a global function which is what the compiler actually calls).
>>
>> It is a legacy limitation. Until we get rid of all the Object base methods for things like opEquals and toHash, we will not be able to fix this.
>>
>> -Steve
>
> Im using DerelictGLFW3, to process events im doing this :
>
> glfwSetMouseButtonCallback(window, &onMouseClick);
>
> onMouseClick function must be nothrow.
>
> But now I can't do anything in this function because I can't convert my code to nothrow.
>
> Can I put a try catch in the body ?
>
> extern(C) nothrow
> {
>     void onMouseClick(GLFWwindow* window, int button, int action, int d)
>     {
>        try
>        {
>            // my code
>        }
>        catch
>        {
>
>        }
>     }
> }
>
> it seems its working but what about performances ?
>
> thanks

You could also try assumeWontThrow. https://dlang.org/library/std/exception/assume_wont_throw.html