|Perl: the Markov chain saw|
Dumb, non-question: How to return 'nothing'.by BrowserUk (Pope)
|on Jun 17, 2011 at 15:40 UTC||Need Help??|
I want to write an iterator that traverses a data-structure:
Problem: elements of the data structure can legitimately return undef. And 0. And -1. And ''. And any other value a scalar can hold.
It is an age old problem. As soon as you define [sic] an undefined value -- or null or nil or bottom -- it become useful to be able to store it.
And once you can store it, it is no longer useful for detecting exceptional, non-error conditions.
What is needed is a 'nothing' place-holder.
But if you try to assign it to any variable, terminates with an exception.
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