uri: Throw when trying to modify URI objects after creation

[TimWolla]

This will also fix a memory leak, since the constructor did not free any pre-existing ->uri.

[nielsdos]

Classic reinitialization problem that pops up every now and then.
The "uri" property does not actually exist, i.e. the error message leads users to believe there is such a property. They may try accessing it. Even if it were private and a user tries accessing it a user would get Cannot access private property . However, they'd get a different error which seems inconsistent to me.

[TimWolla]

Even if it were private and a user tries accessing it a user would get Cannot access private property . However, they'd get a different error which seems inconsistent to me.

I believe a little bit of a leaky abstraction is fine in this case, since this is only triggerable by specially crafted code that a regular user won't come across.

[nielsdos]

For other extensions I've seen a wording used something along the lines of "cannot call constructor twice" or "cannot reconstruct object".

[TimWolla]

For other extensions I've seen a wording used something along the lines of "cannot call constructor twice" or "cannot reconstruct object".

That would not really be applicable to the Exception during unserialization, though. Treating the internal URI as a “super private property” sounds least confusing to me. But let's see what Mate thinks.

[nielsdos]

Well, I find the "super private property" confusing ;) I still prefer a (simple) custom exception messag.

[kocsismate]

FWIW I agree with the change, but I'd also prefer to somehow eliminate the property term from URIs (even the existing ones). People would rightfully scratch their head if they were trying to find these properties.

[TimWolla]

I've adjusted the message to:

Cannot modify readonly object of class %s

The URI classes are actual readonly classes in the stub. The “Cannot modify readonly” matches the phrasing of the readonly property modification error and the “object of class” phrasing has precedent in other error messages. This should be sufficiently descriptive without being misleading and without inventing anything entirely new. WDYT?

[kocsismate]

I'm fine with the message