Re: emacs-27 eebfb72 1/2: Document constant vs mutable objects better, Re: emacs-27 eebfb72 1/2: Document constant vs mutable objects better, Re: emacs-27 eebfb72 1/2: Document constant vs mutable objects better

[Michael Heerdegen]

Štěpán Němec <address@hidden> writes:

> > (eq "" "") => t.  You don't even have to compile.
>
> Yes, but that's a corner case [...]

Sure.  OTOH it is a good demonstration of the fact that not every
"created" string is a new object.  That only one "" exists is one
optimization.  That the compiler sometimes maps (other) equal strings to
the same object is another one.  Anyway, I didn't intend to demonstrate
something special.  But that "" is unique was not as obvious as the
uniqueness of nil for me.

> > It is important.  This once bit me, and it took a long time until I
> > found out what was wrong.
> Here I assume you mean something else than the empty string case?

Yes, it was something different, I don't recall exactly, I guess I was
using strings as keys in some association structure or so.

Michael.