ANSI Common Lisp   20 Files   20.1 File System Concepts

20.1.2 File Operations on Open and Closed Streams

Many functions that perform file operations accept either open or closed streams as arguments; see Section 21.1.3 Stream Arguments to Standardized Functions.

Of these, the functions in the next figure treat open and closed streams differently.

Since treatment of open streams by the file system may vary considerably between implementations, however, a closed stream might be the most reliable kind of argument for some of these functions - in particular, those in the next figure. For example, in some file systems, open files are written under temporary names and not renamed until closed and/or are held invisible until closed. In general, any code that is intended to be portable should use such functions carefully.