Re: find-file dialog in Carbon Emacs is broken

[Richard Stallman]

    Okay, then I misunderstood the meaning of MUST-MATCH.  I think the name is
    confusing (for me at least).  If an existing file is wanted, it should be 
named
    MUST-EXIST or something like that.

    So we can use MUST-MATCH both for OSX and GTK.

The term "match" refers to a concept that applies to completion in
general.  It means that the value the user gives in the minibuffer
must match one of the completion alternatives.

However, I don't object if people rename this argument to
MUST-EXIST and change the doc string.

    I don't know what is best, to have a new function that reads
    directories, or to extend the MUST-MATCH parameter with some value
    that indicates a directory read.

Whether it is a directory is an independent question from whether it
must match an existing alternative.  All four combinations are
meaningful--consider make-directory.  Also, since MUSTMATCH is an
instance of a more general concept of completion, it is better to keep
it the consistent and uniform.

The separate function read-directory-name is therefore the better way.