In a recursive group of readers that parse out a structure, each needs to know how much more is "allowed" for that sub-reader. Say, the outer function decides the entire block is 20 bytes long, then calls the reader for an inner block that might be coded "loop until I run out of input". Passing it just the handle won't work, as it won't know to stop after 20 bytes total before the outer reader returns.

The obvious method is to pass a length in with the handle everywhere. That's crude, though, so bundling the length and the handle into an object seems better. But in Perl, we can go a step farther: how about a tied handle that knows about the length limit? Is there something like that already out there?

—John

In reply to Length-limiting handle by John M. Dlugosz

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