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Dumb, non-question: How to return 'nothing'.by BrowserUk (Patriarch) |
on Jun 17, 2011 at 15:40 UTC ( [id://910184]=perlmeditation: print w/replies, xml ) | 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. A non-storable, non-value that if detected in a while or for loop causes the loop to terminate -- without error. But if you try to assign it to any variable, terminates with an exception. Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
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