Why does the `ToString` trait exist?

help
1

Why was the to_string() method not simply added to the Display trait?

1 Like
2

Sadly, it's more like a historical accident but we can't remove it due to the backward compatibility.

3

Mostly because Display is in core, and String is in alloc, so Display cannot reference String

17 Likes
4

The deeper reason is that Display is polymorphic. Dumping to a String is one implementation, but Display also works with non-allocating output objects.

2 Likes
5

Polymorphic Display does not prevent one from adding a fn to_string(&self) -> String { ... } default implementation. The fact that String is in another crate does.

7 Likes
6

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.