erl has no way of knowing (as I should have from the name of the function, "log") that your function has a side-effect.

This is correct, but if we use an operator like ||=, &&=, .= and so on, implies that at least at that statement, the value of the variable is read AND written, so one could argue that this means that the variable is used at least twice. This has nothing to do with whether or not the expression on the right-hand side has side effects. In other words: 

$P::x ||= (f(),1);

[download]
produces a warning, while the equivalent 
$P::x = $P::x || (f(),1);

[download]
does not.

-- 
Ronald Fischer <ynnor@mm.st>

In reply to Re^4: Why do I get a "used only once" warning here? by rovf
in thread Why do I get a "used only once" warning here? by rovf

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