Are all .el files inside ELPA compliant packages sharing the same namespace?

Question

Assuming that a ELPA directory contains only one version of each Elpa-compliant packages, are the names of all Emacs Lisp files sharing the same namespace?

AFAIK Emacs Lisp does not support the concept of package scope for module name (as other languages like Python support). I would therefore have assumed that all Emacs Lisp files share the same name space. However, some file names in different packages that have the same name but different content, as in the following case:

• lispy-20210121.926/elpa.el
• ivy-20210311.1638/elpa.el

How does Emacs deal with this?

Answer 1

The two files you reference (elpa.el) are used only in installing those packages. If you check the package sources, you'll see that they are only referenced from the Makefile. After the packages are installed, Emacs doesn't need to find them again, so it doesn't matter that they have conflicting names.

Usually, Emacs refers to the load-path to see which directories it should search for files. The load function is used to load files by name:

(load "my-file")

Will search through the load-path until it finds a file with the name my-file.elc, my-file.el, my-file, and possibly a few other variants depending on your system. As soon as it finds a file with a matching name, it loads it and stops looking. If there is a second file with the same name further down in the load path, it is ignored. You can use the command M-x list-load-path-shadows to get a list of all such ignored files.

Consequently, files in a package will be generally be named in a way that is unique to that package (e.g., with a lispy- or ivy-) prefix, with a few exceptions like the one above.

Answer 2

All packages share the same namespace as Elisp does not support separate namespaces.

Packages usually deal with this by prefixing every symbol with a short, unique string. For example, every function in the ivy package is prefixed with "ivy-".