label command outside of a function

[cdg]

The book says that Each label b command in a VM function f should generate a globally unique symbol "f$b" where "f" is the function name and "b" is the label symbol within the VM function's code. That makes sense, but what's the convention when a label command occurs outside a function? For example, in ProgramFlow\FibonacciSeries\FibonacciSeries.vm there are no function commands but there are label commands.

One strategy: in such cases, just use the name of the file in which the label command occurs. Another strategy: fix a function name that isn't used anywhere else, e.g. filename.OUTSIDE_ANY_FUNCTIONS.

Maybe I'm worrying about nothing here. But the fact that this case isn't mentioned in the book or on the forum (so far as I could see) makes me suspect I've missed something.

[cadet1620]

I initialize my label prefix to ClassName$ so that label before the first function end up named ClassName$$label which is guaranteed to never collide with functionName$label.

It would also work to just initialize the label prefix to "" in which case you'd get $label for non-function labels.

(Non-function labels and gotos are a test code aberration; the Jack compiler never generates them.)

--Mark

[cdg]

Got it. Thanks!

On Fri, 2 Sep 2016 at 18:31 cadet1620 [via Nand2Tetris Questions and Answers Forum] <[hidden email]> wrote:

I initialize my label prefix to ClassName$ so that label before the first function end up named ClassName$$label which is guaranteed to never collide with functionName$label.

It would also work to just initialize the label prefix to "" in which case you'd get $label for non-function labels.

(Non-function labels and gotos are a test code aberration; the Jack compiler never generates them.)

--Mark

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