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copied!<p>If you want to make the academic argument, then of course it's not technically necessary to assign a variable more than once. The proof is that all code can be represented in <a href="http://en.wikipedia.org/wiki/Static_single_assignment_form" rel="noreferrer">SSA (Single Static Assignment)</a> form. Indeed, that's the most useful form for many kinds of static and dynamic analysis.</p> <p>At the same time, there are reasons we don't all write code in SSA form to begin with:</p> <ol> <li>It usually takes more statements (or more lines of code) to write code this way. Brevity has value.</li> <li>It's almost always less efficient. Yes I know you're talking about higher languages -- a fair scoping -- but even in the world of Java and C#, far away from assembly, speed matters. There are few applications where speed is irrelevant.</li> <li>It's not as easy to understand. Although SSA is "simpler" in a mathematical sense, it's more abstract from common sense, which is what matters in real-world programming. If you have to be really smart to grok it, then it has no place in programming at large.</li> </ol> <p>Even in your examples above, it's easy to poke holes. Take your <code>case</code> statement. What if there's an administrative option that determines whether <code>'*'</code> is allowed, and a separate one for whether <code>'?'</code> is allowed? Also, zero is not allowed for the integer case, unless the user has a system permission that allows it.</p> <p>This is a more real-world example with branches and conditions. Could you write this as a single "statement?" If so, is your "statement" really different from many separate statements? If not, how many temporary write-only variables do you need? And is that situation significantly better than just having a single variable?</p>

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