Re: How to test for the existence of a 'goto' target label?

[marbux <marbux@...>]

On Sat, Sep 8, 2012 at 4:36 PM, David Given <dg@cowlark.com> wrote:

> I don't believe you can --- my understanding is that labels are pure
> compile-time constructs and don't contain any runtime state. A jump to
> an undefined label should produce a compile-time error, not a run-time

Don't know why, but your post sparked the realization that I can do it
using APIs provided by the particular app Lua is embedded in, the
NoteCase Pro outliner.

It provides APIs that return the doc ID and node ID of the embedded
script being executed, as well as an API to get the node content. So
my script can include a function to fetch its own text as a string,
then evaluate the string for the presence of the given label after
concatenating the input string to add the "::" characters for the
label. Then branch based on the function's boolean return.

I've done something similar recently, extracting the content of the
first Lua long comment in a script to display the script's
documentation in the system default browser, when the script is
selected from a pop-up menu and the user presses the Help button in
the pop-up. So I've got a lot of confidence this idea will work.

Not as compact as I hoped for, but still avoids having to create a
table of all the label's texts to test for branching purposes.

Thanks for the nudge, David.

Best regards,

Paul