11 replies to this topic

[James Leighe]

(C++, MSVC)

This line:

const Vector< ISocket* >* sockets = ((NetworkSystem*)NetworkAPI())->GetSockets();

With 'GetSockets(~)' defined as:

const Vector< Socket* >*
NetworkSystem::GetSockets( )

produces the error:
"cannot convert from 'const Vector<T> *' to 'const Vector<T> *'"

What am I doing wrong here? I just want to get a pointer to a const object.

Thanks as usual guys!

[jwezorek]

Post the rest of the error message or examine it youself ... The problem is probably going to be with the two T's.

i.e isn't there some more to the error message like

with
[
_Ty=foo*
]
and
[
_Ty=const foo*
]

(or whatever)

[Washu]

Socket != ISocket

Also, random C cast FTL.

[James Leighe]

Socket != ISocket

Also, random C cast FTL.

lol i'm retarded thanks guys

[James Leighe]

The random cast is to access the internal version of the network system, NetworkAPI() is meant to be used by the game code.

It's definitely ugly tho.
Thanksfully super rarely used.

[James Leighe]

Can you edit posts anymore?

[Washu]

Casting anything that involves an inheritance hierarchy, using C casts, is dangerous. More importantly, casting something so that you can get access to its internals when you hid those internals away suggests you've got a design issue that you should take a strong hard look at.

[James Leighe]

Well, it's not hidden it's just that NetworkAPI() is defined:

FORCEINLINE INetworkSystem* NetworkAPI( )
{
extern INetworkSystem* _g_NetworkSystemInstance;
Assert( _g_NetworkSystemInstance );
return _g_NetworkSystemInstance;
}

And I only expose game code stuff through 'INetworkSystem' so I needed a 'NetworkSystem'.

How could I improve this?

[James Leighe]

Also, this is in engine code, so it's supposed to see the internals!

[Washu]

When in C++...

If you're going to be casting the pointer, use a static_cast (in this case). As far as how to improve it, I don't know what INetworkSystem looks like, nor what you're using this vector of sockets for.

[James Leighe]

Just building a thread to process my async sockets no biggie.

I used to use C++ casts but man... they sure are hilariously verbose.
I also turn off RTTI since I don't use it.

Anyhow, thanks for your help.

[e‍dd]

I used to use C++ casts but man... they sure are hilariously verbose.

That's a good thing. You want something that's conceptually ugly to be aesthetically ugly too.

Also with C++-style casts, it's much harder to accidentally cast more than you intended, as the C++ compiler will tell you that you've e.g. cast off const-ness unintentionally in a static_cast.