How to prevent cross-talking between instances of the same script (or only allow one instance)?

Question

All,

I have a following problem. I have a script that opens\closes multiple tables and windows, and I create several namespaces to handle this. I also delete those namespaces in <<On Close() of the main window.

I found that when I have two instances of the script running, closing main window in one of them deletes the namespaces and breaks the other script.

How do I make namespaces separate for each instance or, alternatively, how do I only allow one instance of the script\add-in running?

I understand that in

ns = New Namespace();

ns is a reference, and there is a unique name, like "#43" that is assigned every time a namespace is created. I can get that name by <<Get Name() and thus point to a specific and unique namespace, but how can I make it work in multiple instances? Like, ns in one running script instance is referring to "#43", and ns in another running instance is referring to, let's say, "#44"?

mikedriscoll · Answer

To add to ih's comments:

One thing I have noticed is that if you have a script file open with 'names default to here(1)' at the top, and run it to get your first output, then run it again to get a second output, then the first output has elements that are broken because the variables were replaced by those in the second output.

But if you take that exact same script, and call it from an add-in, that problem does not happen. The two report windows function independently as expected. I set up my add-ins in toolbars. You might be able to skip the addin and just add an item to the toolbar, and have that item call your jsl file.  This is all without any other namespace for this (other than one that i use for implementing a 'recall' feature for the GUI). I don't use application builder; I build my add-ins manually, and so mine don't have the 'application' namespace that gets added automatically with the application builder. Don't know if that matters.

This may or may not work for you, I'm not sure exactly what your code is doing. But I wonder if you can eliminate all of the namespaces and just put 'names default to here(1)' at the top, and then run the script from the menu instead of ctrl+R.  Note that when I run my script, I never have two scripts 'running' at the same time, I run them consecutively and then when the second one completes, both outputs are open at the same time.

This may cause issues with debugging though, because you would be debugging and running the script while open (not through the toolbar icon) which means you can only work with the latest output.

vince_faller · Answer

When you say instances, do you mean that you're doing multiple includes?  Or like a function?

Names default to here(1);
create_instance = function({ns},

Eval(EvalExpr(
		nw = new window("Test", 
			window:ns = namespace(Expr(ns << Get name()));
			<< On Close(
				Delete Namespaces(force(1), window:ns);
			),
			Buttonbox("Press Me",
				print(window:ns << Get name());
				show(window:ns:x, window:ns:y);
			)
		)
	));
);
create_instance(ns1 = new namespace({x=14;y=28}));
create_instance(ns2 = new namespace({x=140;y=280}));

This works for me.

*Edit* actually it's even easier.  You don't even need the eval expr because it's not a runtime thing.

create_instance = function({ns}, 
	nw = new window("Test", 
		window:ns = ns;
		<< On Close(
			Delete Namespaces(force(1), window:ns);
		),
		Buttonbox("Press Me",
			print(window:ns << Get name());
			show(window:ns:x, window:ns:y);
		)
	)
);
create_instance(ns1 = new namespace({x=14;y=28}));
create_instance(ns2 = new namespace({x=140;y=280}));

ih · Answer

Hie @miguello,

As you pointed out you need the variable ns to be unique to each script, not just the namespace.  @jthi solves this using Names Default to here(1).  To define this explicitly, and perhaps better understand how it works, try running these two lines in a few different windows,

here:ns = New Namespace();
here:ns:a = random normal();

and then use

show namespaces()

to see see the value of a in each namespace. Calling

here:ns:a

from each individual window will return that window's value.  In another window, run this:

Names default to here(1);
ns = New Namespace();
ns:a = random normal();

and note how it behaves the same way as the previous example. Try that without the here namespace and all reference to a will return the same value, indicating that they are from the same namespace.

So, just putting

Names default to here(1);

at the top of your script might fix your issue.  You also might be able to avoid creating new named namespaces entirely by putting all of those variables you had there right in the here namespace instead.