Casting a UUID to an `int` or to a string works as expected:

```
import uuid

value = uuid.UUID()
str(value)
int(value)
```

but casting to an `hex()` raises an exception:

```
import uuid

value = uuid.UUID()

# uuid instances already have the correct value stored in the `.hex` attribute
value.hex

# this raises `TypeError: 'UUID' object cannot be interpreted as an integer`
hex(value)

# this behaves correctly
hex(value.int)

```

Adding support for `hex()` should be simple enough as adding the following to the UUID class in https://github.com/python/cpython/blob/54752533b2ed1c898ffe5ec2e795c6910ee46a39/Lib/uuid.py#L69:

```
def __index__(self):
    return self.int
```

IMHO implementing "__index__" for UUID would not the correct solution. That method is meant be used by integer-like objects. One of the side effects of implementing "__index__" is that indexing lists with UUID instances would start to work, which is IMHO not correct.

I must admit I was surprised to find out that `hex()` uses `__index__` (which is supposed to return an integer) and not something like a `__hex__` method returning the hex.

Maybe we should change the behaviour of `hex()` instead? (in a backward-compatible way, of course)

hex() used the __hex__() special method in Python 2. This was changed in Python 3 for purpose.

https://docs.python.org/3/whatsnew/3.0.html#operators-and-special-methods

Agreed that UUID should not implement `__index__`. I wouldn't expect to be able to use a UUID as a list index, for example.

This is marked as "behavior", but I have a hard time seeing this as a bug. It's not even a usability bug, given how easy it is to get the hex value of a UUID with `.hex`.

Maybe the UUID class should grow a `__format__` implementation that respects the `x` format specifier?

Note that str() for UUIDs already returns the hexadecimal representation, just with minuses.

I don't see large usability difference between 'uuid={:x}'.format(u) and 'uuid={.hex}'.format(u). And in many case 'uuid={}'.format(u) is appropriate as well.

marking as 'enhancement'.

> I don't see large usability difference between 'uuid={:x}'.format(u) and 'uuid={.hex}'.format(u).

Agreed.

@fcurella: marking as enhancement is fine, but you need to be specific about what exact enhancement you're proposing. Adding __hex__ back isn't a realistic option; it was deliberately removed in Python 3.

I'm not sure what can be done to make UUIDs work with `hex()`. The only way I see is to add back something _like_ `__hex__`, but with a different name.

But in that case, I can see how the same arguments that were originally brought up against `__hex__` could apply to the new dunder method.

I'm closing the issue as 'wont fix'.