Re: newbie problem with nothrow

[Mike Parker via Digitalmars-d-learn]

On Monday, 31 October 2016 at 16:55:51 UTC, WhatMeWorry wrote:

Is there a way to turn off nothrow or work around it? Because 
to me it looks like nothrow prevents me from doing anything 
useful.

extern(C) void onKeyEvent(GLFWwindow* window, int key, int 
scancode, int action, int modifier) nothrow
{
    if(queue.roomInQueue())
    {
        auto event = new Event;
        event.type = EventType.keyboard;
        event.keyboard.key = cast(Key) key;

        // etc.
}

Error: function 'event_handler.CircularQueue.roomInQueue' is 
not nothrow
Error: function 'event_handler.onKeyEvent' is nothrow yet may 
throw


The compiler wouldn't let me just remove "nothrow" from the 
function. I tried a kludge where I had this function just pass 
all its parameters to another throwable function, but this 
caused errors as well.

So I'm stuck.  Anyone know how to proceed.
Thanks.

If you can't change the interface of CiricularQueue to be nothrow 
and don't want to wrap everything in a try...catch block, then 
just use a dynamic array. You can also use the old C union trick 
to avoid the need to allocate every event. That's the same thing 
SDL does. Something like this:

```
enum EventType {
   key,
   mouse,
}

struct KeyEvent {
   EventType type;
   ...

   this(...)
   {
        this.type = EventType.key;
        ...
   }
}

struct MouseEvent {
   EventType type;
   ...

   this(...)
   {
        this.type = EventType.mouse;
        ...
   }
}

union Event {
   EventType type;
   KeyEvent key;
   MouseEvent mouse;
}

Event[] eventq;
extern(C) void onKeyEvent(GLFWwindow* window, int key, int 
scancode, int action, int modifier) nothrow {
    Event event;
    event.key = KeyEvent(window, key, scancode, action, modifier);
    eventq ~= event;
}
```