BUG: Variables calculations overwritten

[slspencer]

• Describe the bug

In the Variables Table, a Variable's calculated value can be overwritten from a formula farther down in the Variables table. The updated calculated value is then used to draw the pattern.
The Variables Table should not allow backward updates, this creates recursion. I can provide example of this, but the base problem is ability to update variables that are defined earlier in the table.

In this example, the variable is overwritten directly with a constant, even though the formula wasn't overwritten.

[pmjherman]

Isn't this logical behaviour? By inserting the formula "#LegTaperOffset=6", the program will execute the formula #LegTaperOffset2=#LegTaperOffset=6, which is a double assignment that changes both #LegTaperOffset and #LegTaperOffset2, both to the value 6.
Maybe the formula editor should refuse a formula that contains an assignment, because there is normally no reason to use this. If you would have used another operator, e.g. "#LegTaperOffset * 6", it would have worked normally

[DSCaskey]

Maybe the formula editor should refuse a formula that contains an assignment, because there is normally no reason to use this.

No. Don't assume anything. The math parser allows for conditional expressions... meaning you should be able to set a variable based on a condition. Removing the use of = breaks this functionality, and most likely some existing patterns.

[DSCaskey]

I've found a fix. Just need to clean up some commits.

[slspencer]

This issue is about whether we want to allow assignment using Variable formulas.
So @DSCaskey if you think we should be able to set values of variables in formulas then this isn't an issue.

Here's an example of where it works properly:
Var X formula is '3'
Var Y formula is '2'
Var Z formula is '((Y>1) ? (X=X + Y) : Y)
The result is that X = 5, Y = 2, Z = 5
Saving this file and reopening it has the same result. X=5, Y =2, Z = 5

Here's an example of where it doesn't work properly, where the '==' is typo'd as '=' in an IF statement:
Var Strange = '((X=1)?(X=2):(X=3))

[slspencer]

@DSCaskey - this is good that you've found out how to prevent the backward variable assignment.
But is it really a fix when Var2's formula assigns a value to Var1 but the result is that the value is actually assigned to Var2? The results don't match the formula, which may make the pattern difficult to troubleshoot.
This may not be a good result overall.

Is there a way to validate the operator of an IF statement condition in qmuparser? This may be the problem we want to solve.