Number block accepts non-number value

[ewpatton]

Typically, the number block rejects values that do not parse as numbers. For example, typing cat and pressing enter will reject the string and revert the block to its original value. However, if one clicks on the workspace background the block will accept the change.

[ColinTree]

Refer to this line

https://github.com/mit-cml/appinventor-sources/blob/master/appinventor/blocklyeditor/src/blocks/math.js#L24

I wondered why we use
new Blockly.FieldTextInput('0', Blockly.Blocks.math_number.validator) (Text field with a custom validator)
instead of
new Blockly.FieldNumber(0) (blockly built-in number field)
directly?

[ewpatton]

@ColinTree The implementation of the number block in App Inventor predates the implementation of Blockly.FieldNumber. I'm not opposed to switching from our existing implementation to FieldNumber, but it will need significant testing to ensure we don't break existing apps when we switch.

[SusanRatiLane]

Additional testing indicates that this is a display problem. The change event for the number block is never called, and the stored value is not saved. The block displays as if it has changed until the project is reloaded.

[BeksOmega]

Dug into this a bit b/c fields are my jam. Turns out this is a bug inside Blockly, but it's fixed in the latest version.

Explanation of why this occurs:

1. When you enter "cat" the validator returns null here.
2. This causes the field to reset the text to the previous value here.
3. Then when the base setValue gets called here it sees that the old value and new value match here.
4. So setText never gets called, so it still displays "cat".

It could be fixed by monkey-patching the individual field's setValue function. Or by monkey-patching Blockly.Field's setValue function. But those aren't great options :/

[ewpatton]

@BeksOmega I would just go ahead and monkey patch it.