Make time parameter optional for Property

[anne-gropler]

Description

The callback in a CallbackProperty could do anything, even ignoring the time parameter.

Users in typescript strict mode always have to pass a time parameter, even if their callback doesn't use it, and are forced to write something like .getValue(undefined!).

This pull requests makes the time paramter optional for all Propertys, so that users can write .getValue() without problems. As suggested in the linked issue comments, a default for time (i.e. JulianDate.now()) is used for compatibility. This default was added for all properties, because the abstract Property could otherwise not make the time parameter optional.

Issue number and link

Closes #12009

Testing plan

Added tests that check that JulianDate.now() is called when time is undefined.

Built Cesium and linked it in another typescript app (strict mode) and checked that the time parameter is indeed optional now.

Author checklist

• I have submitted a Contributor License Agreement
• I have added my name to CONTRIBUTORS.md
• I have updated CHANGES.md with a short summary of my change
• I have added or updated unit tests to ensure consistent code coverage
• I have updated the inline documentation, and included code examples where relevant
• I have performed a self-review of my code

[github-actions]

Thank you for the pull request, @anne-gropler!

✅ We can confirm we have a CLA on file for you.

[ggetz]

Thanks for the PR @anne-gropler! I have a two comments which apply to each of the files changed.

[ggetz]

This will allocate a new object each time getValue is called without a time parameter. To avoid a performance hit, we should use a scratch variable.

[anne-gropler]

Do you mean something like this?

let timeScratch = new JulianDate();

/**
 * Gets the value of the property.
 *
 * @param {JulianDate} [time=JulianDate.now()] The time for which to retrieve the value. If omitted, the current system time is used.
 * @param {object} [result] The object to store the value into, if omitted, a new instance is created and returned.
 * @returns {object} The modified result parameter or a new instance if the result parameter was not supplied or is unsupported.
 */
CallbackProperty.prototype.getValue = function (time, result) {
    if (!defined(time)) {
    timeScratch = JulianDate.now();
  }

  return this._callback(defined(time) ? time : timeScratch, result);
};

[ggetz]

Close! The JulianDate.now function is designed to take a result parameter. Instead of creating a new JulianDate object, it'll be copied into the existing scratch variable:

const timeScratch = new JulianDate();

/**
 * Gets the value of the property.
 *
 * @param {JulianDate} [time=JulianDate.now()] The time for which to retrieve the value. If omitted, the current system time is used.
 * @param {object} [result] The object to store the value into, if omitted, a new instance is created and returned.
 * @returns {object} The modified result parameter or a new instance if the result parameter was not supplied or is unsupported.
 */
CallbackProperty.prototype.getValue = function (time, result) {
    if (!defined(time)) {
    time = JulianDate.now(timeScratch);
  }

  return this._callback(time);
};

Does that make sense?

[anne-gropler]

Ohh, right! This does make more sense!

I adapted the code. Thank you for your patience!

[ggetz]

I would suggest:

Suggested change

	* @param {JulianDate} [time=now] The time for which to retrieve the value. If omitted, now is used.
	* @param {JulianDate} [time=JulianDate.now()] The time for which to retrieve the value. If omitted, the current system time is used.

just to be a bit more precise.

[anne-gropler]

done!

[ggetz]

Awesome, thanks @anne-gropler!

[ggetz]

One last thing: Please move this under a new section.

### 1.121 - 2024-09-01

[anne-gropler]

new month, new section :) done!

[ggetz]

Perfect, thanks for the PR @anne-gropler!