What does Foucault mean by "the author-function" in his essay "What Is an Author" ?

Foucault’s essay “What is an Author?” might be seen as an
example of (post)structuralism, if not of the post-human. Foucault is not interested in
the author as a person. That view of the author as a person would be, generally
speaking, the view of pre-critical humanism, in which the author is credited as being
“real” and as being in complete control of the text that the author produces. (Most
readers today, despite Foucault, continue to view the author as in this pre-critical
humanist way. They care about the life of the author, for example, and believe that the
author is the ultimate authority when it comes to determining meaning in a given
literary work.)

Instead of seeing the author simply as a
person who writes, Foucault sees authorship as a function of the writing itself.
Foucault identifies multiple functions of the author:

1.
Author as a legal construction, connected to questions of heresy, slander, and libel.
Today, we might focus on the importance of the author to copyright laws and charges of
plagiarism.

2. Author as a literary construction, connected
to questions of literary merit. A poem bearing my name, for example, simply won’t
receive the same attention as a poem bearing Wordsworth’s name, even if my poem is
better. Wordsworth’s poems have literary merit and mine
don’t.

3. Author as a unifying construction, allowing
seemingly very different texts to be unified under a single concept and allowing new
texts to be evaluated against old texts for consistency of quality. Naming Homer as the
author of both the Iliad and the Odyssey, for example, allows us to overlook the obvious
differences between those two works and to read them as closely related texts that
express deeply held values of the ancient Greeks. Simply put, this function shows our
belief that authors are internally consistent: they write about the same themes over and
over, for example, and they’re either always good or always bad at what they
do.

I’ve always tried to read this essay alongside the New
Critical statements on the intentional fallacy and Roland Barthes’ essay “The Death of
the Author.”