mutating arguments a la midirecv

[preferred.nomenclature]

After learning how to program in that other JS language (JavaScript), I'm finally getting the hang of Reaper's JSFX. I am trying to implement my own pseudo-array methods using pseudo-object notation, and I've got

someArray.push(foo)

working but just realized there is no function pop() I could write to satisfy the use case

foo = someArray.pop()

since the return value from pop() doesn't get assigned to anything (...do I have that right?).

Then I thought maybe I could write it something like

someArray.pop(foo)

and mutate foo within the function, since that seems to be how midirecv works (you call midirecv(foo, bar, baz) and on the next line foo bar and baz have values they didn't have before) - but I'm guessing that's an implementation specific to midirecv.

I suppose I'm just looking for confirmation that there's no way in JS to pass in a variable by name, mutate it within a function and access that mutated value by name again outside of the function. (and/or to write a function that assigns a value to the left of = regardless of of the right side value it was called on)

Thanks! I look forward to sharing some fun MIDI FX as soon as I've tinkered with them to my satisfaction.

[geraintluff]

You're correct, modifying arguments is a privilege only built-in functions get.

I'm not sure what you mean when you say "the return value from pop() doesn't get assigned to anything" - someArray.pop() will return a value like any other function. I don't see why you couldn't implement that function, unless I've misunderstood what you want.

[preferred.nomenclature]

Originally Posted by geraintluff

someArray.pop() will return a value like any other function. I don't see why you couldn't implement that function, unless I've misunderstood what you want.

You're right, I checked again and it was my implementation that was buggy. Thanks!

[mschnell]

The "JS" in "JSFX" has absolutely nothing to do with "Java (Script)". so don't do any comparing between those languages (Java family and eel).

-Michael

[geraintluff]

Originally Posted by mschnell

The "JS" an "JSFX" hat absolutely nothing to do with "Java (Script)". so don't do any comparing between those languages (Java family and eel).

Given your comment was about separating similarly-named programming languages, I feel honour-bound to point out that JavaScript is not in the "Java family", just has a similar name.

[IXix]

Originally Posted by preferred.nomenclature

I suppose I'm just looking for confirmation that there's no way in JS to pass in a variable by name, mutate it within a function and access that mutated value by name again outside of the function

No, but there is this little trick which can sometimes be useful...

function func(n*)
(
  n.x += 1;
  n.y += 1;
);

foo.x = 0;
foo.y = 1;

func(foo);

[geraintluff]

Originally Posted by IXix

No, but there is this little trick which can sometimes be useful...

OK, am I looking in the wrong place for documentation? Which versions of REAPER support this syntax? Where's the specification for this?

Returning/ multiple values using the pseudo-object macros is nice, but I've gently wished for this *particular* bit of syntax for a while now.

Is there a wiki version of the spec which has these things added? Or somewhere like GitHub where people can make pull requests to update the official docs?

[IXix]

Originally Posted by geraintluff

OK, am I looking in the wrong place for documentation? Which versions of REAPER support this syntax? Where's the specification for this?

That doesn't seem to have made it into the docs yet. I only know about it from hanging around the pre-release forum. Give it time, it's only been four and a half years.

v4.53 - October 4 2013
+ JS: added !== and === operators (exact comparisons)
+ JS: avoid excess undo state save on finishing a slider drag
+ JS: user functions can now have namespaces as parameters -- function t(a*) ( a.foo = 1; );
+ JS: user functions can now have their own default namespaces -- function foo.bar() ( this.a=1; );
+ JS: user functions can now override builtin functions -- function sin(x) ( x - x^3/6 + x^5/120 );

Originally Posted by geraintluff

Is there a wiki version of the spec which has these things added? Or somewhere like GitHub where people can make pull requests to update the official docs?

Not that I'm aware of. The docs do tend to lag a bit.

[geraintluff]

Originally Posted by IXix

I only know about it from hanging around the pre-release forum.

Ah, great! Thanks.

[preferred.nomenclature]

Very cool, glad I asked!

[preferred.nomenclature]

Finally got to play around with this, it's a game changer. You can mutate the value of n itself, not just its n.whatevers. You can't even do that in JavaScript! Any other secrets we should know about?

[IXix]

Originally Posted by preferred.nomenclature

Finally got to play around with this, it's a game changer. You can mutate the value of n itself, not just its n.whatevers. You can't even do that in JavaScript!

Oh yeah, I forgot that you could do that. I suppose that means that you could actually do what you wanted to in terms of passing variables into a function and altering their values. You just have to use the namespace passing syntax...

function test(a*, b*)
(
  a *= 2;
  b *= 3;
);

x = 2;
y = 3;

test(x, y);

Originally Posted by preferred.nomenclature

Any other secrets we should know about?

The functions mem_get_values(offset, ...) and mem_set_values(offset, ...) , added in 5.28, don't seem to be in the docs either...

mem_set_values(buf, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
mem_get_values(buf, a, b, c, d, e, f, g, h, i, j);

There's also the entirely mysterious export_buffer_to_project() (added in 5.1) which you'll find lurking on line 1283 of Super8. I know nothing about how that works except that it will dump a buffer into a media item in the project. I've been meaning to figure out how it works for ages but haven't gotten around to it yet.