I'd say the island and the fenced in area are very similar. Moving a fence doesn't change the nature of the fenced in area (unless you let the fence intersect with itself). As for the island growing or shrinking, well, that means you have to move the sea. Just like you have to move the fence. No difference.

As for adding a new line to the end of the file, the end-of-file point moves - just like the closing brace "moves" if you add a line to the end of the block. The fact that in some OSses there isn't an end-of-file byte because it can be determined by another piece of information kept by the OS isn't relevant - that happens on a far lower level than Perl.

A file is a block that follows the same scoping rules as blocks bound by braces.

Abigail