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Talk:Null object: Difference between revisions
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::: Please stop changing task names and descriptions; we want to avoid accidentally making implementations of tasks wrong. Well, unless you're prepared to go through all the implementations and ''fix'' anything invalidated yourself. (Not all languages have a type system that admits nulls — i.e., a bottom to the pointer/reference type system — but where that's the case, there's typically other mechanisms for saying the broader statement of “there's nothing here”.) –[[User:Dkf|Donal Fellows]] 09:30, 11 November 2011 (UTC)
== solutions that need review ==
* Basic: missing actual code
* Javascript: testing for defined
* Maxscript: test for undefined
* MUMPS: test for defined
* PARI/GP: can't tell if this example is about null or not.
* Perl: explains undef as a value but doesn't show how to tell the difference between the variable having a value and the variable actually being undefined. if that difference is not possible then this should be explained. i suppose it's the same as Perl 6, there it is explicitly stated that null objects can not be tested for.
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