Limit values that lead to an error.

[kaiwas]

Is there an existing issue for this?

• I have searched the existing issues

Problem description

In this example I'll mention sketcher, but in reality this behavior is present almost everywhere.
If we enter values that “break” the model or sketch, a breaking action is performed, which can be difficult to fix (it’s good if canceling the action helps).

It would be great to display a message about “valid” values when entering “breaking” data.
In the example of this sketch, the value 51 is acceptable.
at a value of 50 the sketch will break.
To avoid a breakdown, expect a pop-up message "The value cannot be less than or equal to 50"
Moreover, if the value 50 was entered, then two behaviors are possible:

1. The sketch leaves all the values ​​that were before entering the new one.
2. The value closest to the acceptable value is accepted (in this case, for example, 50.001)

Link for discussion on the forum
https://forum.freecad.org/viewtopic.php?t=87591

Test file is attached

Limit_value.zip

Full version info

0,21 & any versions

Subproject(s) affected?

None

Anything else?

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[maxwxyz]

not sure if this is possible as all values would need to be calculated.

[kaiwas]

Yes. I also think that this is not an easy task.
some kind of buffer may be required. into which the “previous/correct” data is entered. And if the task ends with a breakdown and an error, then a “rollback” is made to these values. (this is one of the possible options).
Now everything is just silently breaking down.
You can try to track the cause in the console. But in my opinion, the average user is not required to know that the console exists

[kaiwas]

Add to the collection of examples where what is discussed in this topic would be useful.
https://forum.freecad.org/viewtopic.php?p=758678
At a certain value, the segment in the sketch becomes zero length and everything breaks.

[kaiwas]

a simple idea emerged. Which will not be difficult to implement.
When a small, barely noticeable icon with an exclamation mark lights up in the view tree, the program takes a step back (Undo / AutoCtrl+Z) and displays a message that "the “object OBJECTNAME ” is broken. Repeat the operation with other values". In This case, the object itself is highlighted in red.