How can I update all Dictionary entries in place?

[CTMacUser (Daryle Walker)]

@CTMacUser

The updateEach loop is the same as what's needed for a mutating forEach .

...

Glancing over the just-referenced thread: woah, the values partial accessor conforms to MutableCollection ?!... Yes, it's that way in the current Git repo. I wonder if we could use that code somehow; there should still be a more direct way for a dictionary to mutate a value.

I had hope, but when I looked at one of the other mutating-forEach threads:

@Nevin

This implementation falls into a performance trap, as described in the documentation for indices . Essentially, indices might hold a reference to self , in which case mutating self while iterating over indices creates an extra copy of self . In the standard library, this occurs for Dictionary.Values .

The recommended approach is to manually advance an index.

So we need a set-able Value subscript directly on Dictionary.