Default values not working.

adamohern · April 2016

I'm filling in the default values in my feature. They look fine in the code (no error flags), but they seem to be ignored when instantiating the feature. Is there a trick to getting defaults to work properly?

kevin_o_toole_1 · April 2016

That defaults map controls the default values when your feature function is called from another FeatureScript feature, or when old features that lack a new parameter regenerate.

This does NOT control the user default value when creating this feature for the first time. That's controlled separately via an annotation.

To change the user-visible default for booleans, enums, and strings, use the "Default" annotation:

annotation { "Name" : "Hollow", "Default" : false }
definition.isHollow is boolean;

To change the user-visible default for a length, angle, or number, you'll need to specify it inside a value bound, which you can create as a constant before your feature:

const MY_BOUNDS =
{
    "min"    : -TOLERANCE.zeroAngle * radian,
    "max"    : (2 * PI + TOLERANCE.zeroAngle) * radian,
    (degree) : [0, 45, 360],
    (radian) : 1
} as AngleBoundSpec;
...
    isAngle(definition.myAngle, MY_BOUNDS);
...

Note that the default values are different based off a users' default units. Check out the valueBounds module for some examples of bounds used in Onshape features.

I agree the difference is confusing now, but fortunately this stuff will be documented better in 1.45.

adamohern · April 2016

Oh wow, I was way off! Many thanks for the quick response. I'm sure I'll work through it.

adamohern · April 2016

I'm working with US stock, so my default edge round is 1/4" regardless of the user's display unit. I'm currently brute-forcing that using:

export const EDGE_ROUND_BOUNDS =
{
    "min"        : -TOLERANCE.zeroLength * meter,
    "max"        : 500 * meter,
    (meter)      : [1e-5, 0.00635, 500],
    (centimeter) : 0.635,
    (millimeter) : 6.35,
    (inch)       : .25,
    (foot)       : 0.02083333,
    (yard)       : 0.006944444
} as LengthBoundSpec;

This is obviously redundant. Is there a cleaner way to do this if all I want is a default value regardless of display unit?

kevin_o_toole_1 · April 2016

For all of Onshape's features, we use round numbers in all units (it's less visually noisy) so the need for a simpler way never came up. But you're bringing up a good point here: a standard size is definitely a legitimate use case.

Unfortunately, the precondition analysis expects the BOUNDS that you provide to be declared as a map literal, so you can't even make a simple function like lengthBoundsWithExactDefault(1/4 * inch) which would return the right thing.

For now the syntax you're using is the best thing available, but yeah, it's not great. We'll think about making the precondition analysis smarter, and adding lengthBoundsWithExactDefault to the Standard Library.

ilya_baran · April 2016

An alternative is to only specify inches in the bound (you'd need the min and max in inches too) -- then the default would be "0.25 in" regardless of the document units. Not obvious to me if it's more or less desirable than a specification of the same length in document units -- since the design intent for that value is really inches.

adamohern · April 2016

You mean like this?

export const EDGE_ROUND_BOUNDS =
{
    "min"        : -TOLERANCE.zeroLength * inch,
    "max"        : 50000 * inch,
    (inch)      : [1e-50, 0.25, 50000]
} as LengthBoundSpec;

adamohern · April 2016

kevin_o_toole_1 said:

We'll think about making the precondition analysis smarter, and adding lengthBoundsWithExactDefault to the Standard Library.

I would recommend reconsidering the requirement for a bounds object, and allow something simpler, like the "Default" parameter in a boolean query. Bounds would, of course, be the more powerful method for advanced users, but I think a typical user would prefer a more straightforward way of setting a default value without bothering with the rest of it.

Default values not working.

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