[chuck-dev] fixed array compatibility checking (PATCH)

Robin Haberkorn robin.haberkorn at googlemail.com
Wed Sep 5 21:29:48 EDT 2012


Here's another minor bug fix.

Consider this example:

UGen @osc[2];
new SinOsc @=> osc[0];
new PulseOsc @=> osc[1];

It will work because the type checker will consider SinOsc/PulseOsc and
UGen compatible for assignment (using the "isa" function which in turn
is using the <= operator). This is because Chuck_Type "<=" will check
that SinOsc is a child of UGen.

However, unintuitively you cannot use the array constructor:

[new SinOsc, new PulseOsc] @=> UGen @osc[];

Since the left-hand-side type (Osc[] in this case) is not considered
compatible to UGen[]. Neither are they directly the same nor are they
That's because "<=" does not check for the arrays' "actual" types (Osc
and UGen) being compatible.

You must either declare the "osc" variable with the same type as the
constructed array:

[new SinOsc, new PulseOsc] @=> Osc @osc[];

or you have to cast the array members to UGen so the lhs type is
(predictably) UGen[]:

[new SinOsc $ UGen, new PulseOsc $ UGen] @=> UGen @osc[];

Both options are not very intuitive for the user. The "Osc" class/type
is not even documented I think. Not to mention that it's not always easy
to guess the type of a constructed Object array.

The attached patch fixes that by allowing arrays of the same depth and
derived "actual" types being considered compatible.

I think this is the last array patch for the time being, though I'm
tempted to implement support for map keys in the inline array
constructor :-).

Best regards,
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