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I know what recursion is in programming. I do understand the basics of version control systems (have used svn that is). But I have often wondered what the meaning of "recursion" or "recursive" is with respect to version control systems.
What does a function calling itself have to do with working with files and directories in a version control system?
The specific meaning of "recursive" in this context is "operating on a directory and its contents, including the contents of any subdirectories".
The word "recursive" is used here, because at least conceptually, this is easily implemented by a recursive algorithm:
procedure check_in_directory (d : directory)
for each entry e in d <== recursive exit after last entry in directory
if e is a file
check_in_file(f)
if e is a directory
check_in_directory(e) <== recursive call
The recursive structure of this procedure matches the recursive definition of a directory:
A directory contains zero or more directory entries
A directory entry is either a file or a directory
This approach -- writing a function whose structure matches the definition of the data type you are processing is often referred to as structural recursion.