Empty handle

[glennhickey]

This is probably a dumb question, but what's the best way to check if a handle is empty? This comes up, for example, when replacing code of the type

Node* node = nullptr;
// do some stuff
if (node != nullptr) {
   // more stuff
}

Obviously, I can do the same thing with a handle_t*, but that's pretty ugly. I'd rather use handle_t directly. Is there a way to do this?

[ekg]

There aren't really empty handles. In my context I'm using the entire namespace. 0 is a valid handle. You might want to do something different.

On Thu, May 23, 2019, 18:18 Glenn Hickey notifications@github.com wrote:

This is probably a dumb question, but what's the best way to check if a handle is empty? This comes up, for example, when replacing code of the type

Node* node = nullptr; // do some stuff if (node != nullptr) { // more stuff }

Obviously, I can do the same thing with a handle_t*, but that's pretty ugly. I'd rather use handle_t directly. Is there a way to do this?

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[glennhickey]

Any suggestions? Can I switch from handles to id's and assume id==0 is a null id?

On Thu, May 23, 2019 at 12:56 PM Erik Garrison notifications@github.com wrote:

There aren't really empty handles. In my context I'm using the entire namespace. 0 is a valid handle. You might want to do something different.

On Thu, May 23, 2019, 18:18 Glenn Hickey notifications@github.com wrote:

This is probably a dumb question, but what's the best way to check if a handle is empty? This comes up, for example, when replacing code of the type

Node* node = nullptr; // do some stuff if (node != nullptr) { // more stuff }

Obviously, I can do the same thing with a handle_t*, but that's pretty ugly. I'd rather use handle_t directly. Is there a way to do this?

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.

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[glennhickey]

I'll just add, this seems like a hole in the interface. Is it unreasonable to have a null_handle constant value somewhere and ask all implementations to never use it for a valid handle? Adding this wouldn't affect existing client code nor, I suspect, most graph implementations.

[ekg]

I guess that's fine. What would produce it?

It's kind of like the one past end step iterator things we have. There, we need a way to signal that a path is done.

On Thu, May 23, 2019, 19:18 Glenn Hickey notifications@github.com wrote:

I'll just add, this seems like a hole in the interface. Is it unreasonable to have a null_handle constant value somewhere and ask all implementations to never use it for a valid handle? Adding this wouldn't affect existing client code nor, I suspect, most graph implementations.

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[glennhickey]

I think the fact that we can declare all these handles without initializing them means we should be able to check if they're null/empty. For regular handle's I was just thinking something simple as #23.