When wrapping C code that tries to allocate memory resources via functions such as

    X* X_create();

should one call `onOutOfMemoryError();` upon null return?

Making more D wrappers `nothrow @nogc`.

On Wednesday, 24 March 2021 at 07:58:22 UTC, Per Nordlöw wrote:
> When wrapping C code that tries to allocate memory resources via functions such as
>
>     X* X_create();
>
> should one call `onOutOfMemoryError();` upon null return?
>
> Making more D wrappers `nothrow @nogc`.


There are several ways to do that. In addition to onOutOfMemoryError, you can use a static instance or `if (somePtr is null) assert(0);`

  void v() @nogc nothrow
  {
    __gshared oom = new OutOfMemoryError();
    auto X* = X_create();
    if (X is null)
        throw oom;
  }

On Wednesday, 24 March 2021 at 08:31:19 UTC, Basile B. wrote:
> There are several ways to do that. In addition to onOutOfMemoryError, you can use a static instance
>
>   void v() @nogc nothrow
>   {
>     __gshared oom = new OutOfMemoryError();
>     auto X* = X_create();
>     if (X is null)
>         throw oom;
>   }

How is that better than

    void v() @nogc nothrow
    {
        auto X* = X_create();
        if (X is null)
            onOutOfMemoryError();
    }

considering the fact that accessing `__gshared` state is neither `@safe` nor `pure`? Which, in turn, makes `v()` unconditionally unsafe and unpure regardless of safety and purity of `X_create()`.

On Wednesday, 24 March 2021 at 08:51:34 UTC, Per Nordlöw wrote:
> On Wednesday, 24 March 2021 at 08:31:19 UTC, Basile B. wrote:
>> There are several ways to do that. In addition to onOutOfMemoryError, you can use a static instance
>>
>>   void v() @nogc nothrow
>>   {
>>     __gshared oom = new OutOfMemoryError();
>>     auto X* = X_create();
>>     if (X is null)
>>         throw oom;
>>   }
>
> How is that better than
>
>     void v() @nogc nothrow
>     {
>         auto X* = X_create();
>         if (X is null)
>             onOutOfMemoryError();
>     }
>
> considering the fact that accessing `__gshared` state is neither `@safe` nor `pure`? Which, in turn, makes `v()` unconditionally unsafe and unpure regardless of safety and purity of `X_create()`.

In now way. But in your question you mentioned @nogc nothrow and not @safe and pure.

On Wednesday, 24 March 2021 at 08:31:19 UTC, Basile B. wrote:
> On Wednesday, 24 March 2021 at 07:58:22 UTC, Per Nordlöw wrote:
>> When wrapping C code that tries to allocate memory resources via functions such as
>>
>>     X* X_create();
>>
>> should one call `onOutOfMemoryError();` upon null return?
>>
>> Making more D wrappers `nothrow @nogc`.
>
>
> There are several ways to do that. In addition to onOutOfMemoryError, you can use a static instance or `if (somePtr is null) assert(0);`
>
>   void v() @nogc nothrow
>   {
>     __gshared oom = new OutOfMemoryError();
>     auto X* = X_create();
>     if (X is null)
>         throw oom;
>   }

why are you creating oom variable before the if(x is null) check?

On Wednesday, 24 March 2021 at 10:25:21 UTC, Basile B. wrote:
> In now way. But in your question you mentioned @nogc nothrow and not @safe and pure.

Ok, thanks.

Note that core.exception.onOutOfMemoryError is already qualified as @nogc nothrow pure @trusted.