It is important to understand how the current package (that is, the value of the Common Lisp variable
) is determined when running Lisp operations such as evaluation or compilation commands in a buffer. Usually it is obvious: most Lisp source files have a single
form. The Editor uses the specified package as the current package when you evaluate or compile code in that buffer, or perform some other operation that depends on the current package.
However it is possible for a source file to contain multiple
forms, or none at all. In this case, the Editor uses a suitable binding for the current package depending on the location in the buffer, as described below. This means that you do not have to worry about setting the package explicitly before evaluating part of a buffer, and that operations within a buffer use the expected current package.