Issue 6224 - Add ownerTid() property.

[ghost]

http://d.puremagic.com/issues/show_bug.cgi?id=6224

Nothing too controversial. But since the returned type is a struct I figure it's better to throw an exception rather than the user getting a segfault when they try to call ownerTid.send().

Additionally I've removed Tid.send, it was duplicated code but isn't required anymore since UFCS can take its place.

[alexrp]

By convention, we append Error or Exception to exception classes.

[ghost]

Well that convention seems to be only partially followed, e.g. MessageMismatch, OwnerTerminated, LinkTerminated, PriorityMessageException, MailboxFull.

But why are we using some form of Hungarian notation in a statically typed language?

[alexrp]

This is common convention for many, many languages, regardless of static or dynamic typing. It's helpful because you don't have to go and look at the class definition to figure out what a PriorityMessage might be. The Exception lets you know immediately. It also avoids conflating exception types with the general type 'namespace'.

I don't know why half of the types in this module don't follow the convention.

[monarchdodra]

One thing that is very helpful (to me), is knowing whether the object thrown is an Exception or an Error. The fact that it is in the name keeps things self documented.

[ghost]

I've renamed it to TidMissingException. This will make it usable for any future functionality (e.g. if we ever add the ability to iterate child threads but one of them exits right before we check its Tid).

[monarchdodra]

Whilst we're adding exceptions, how about a NullTidError ? This would be thrown when you call send with an empty Tid. It sure as hell beats having an object violation.

Just throwing it out there.

[alexrp]

I'm wondering if maybe this should be an Error? Isn't it a logical error to try to get a Tid when none is present?

[ghost]

I can't say for sure, but I think a thread which spawned another one could exit while the child thread is still running. In that case ownerTid would likely be empty. I'll cc Sean about it: @complexmath

[alexrp]

@complexmath ping?

[andralex]

I think we should not add to Errors without good reason. Let's keep this an exception.