Avoid panics

[cheatsnake]

A fairly trivial check of division by zero causes panic. Do you plan any protection against such cases? And a way to avoid panics?

panic: runtime error: integer divide by zero [recovered]
        panic: runtime error: integer divide by zero

goroutine 170 [running]:
github.com/maja42/goval/internal.Evaluate.func1()
        /home/user/go/pkg/mod/github.com/maja42/goval@v1.3.1/internal/evaluate.go:11 +0xa5
panic({0x69d820?, 0x9198b0?})
        /usr/local/go/src/runtime/panic.go:914 +0x21f
github.com/maja42/goval/internal.div({0x68b580?, 0x8f77e0?}, {0x68b580?, 0x8f77c0?})
        /home/user/go/pkg/mod/github.com/maja42/goval@v1.3.1/internal/parserUtils.go:207 +0x1cd
github.com/maja42/goval/internal.(*yyParserImpl).Parse(0xc000235200, {0x76a720?, 0xc000230240?})
        parser.go.y:100 +0x132e
github.com/maja42/goval/internal.Evaluate({0xc00020a378?, 0x406f17?}, 0xc0002448a0?, 0x7674b0?)
        /home/user/go/pkg/mod/github.com/maja42/goval@v1.3.1/internal/evaluate.go:18 +0x85
github.com/maja42/goval.(*Evaluator).Evaluate(...)
        /home/user/go/pkg/mod/github.com/maja42/goval@v1.3.1/evaluator.go:31

[maja42]

Adding a check and returning a specific error instead of a panic would indeed be possible.
But it doesn't protect against all panics (called functions can also panic).
Would there be a benefit of handling this case specifically?

[cheatsnake]

Adding a check and returning a specific error instead of a panic would indeed be possible. But it doesn't protect against all panics (called functions can also panic). Would there be a benefit of handling this case specifically?

Perhaps some special mode (e.g. you can call it safe or limited) where only those actions will be performed that are guaranteed not to cause panic, but only throw an error, would be a good solution.

eval := goval.NewSafeEvaluator()
result, err := eval.Evaluate("2 / 0")

[sashakoshka]

called functions can also panic

It is possible to ensure called functions do not panic, because the functions do not originate from this module and are added at the application developer's discretion.

Would there be a benefit of handling this case

The evaluated expression may be something entered by a user, and there is no good way to check if the user input contains divisions by zero without re-implementing the functionality in this module. The expected behavior of a program in this scenario is to display a readable error to the user, not a panic, which would be far less awkward if Evaluate returned a division by zero error.

[maja42]

Detecting division by zero sounds reasonable. I'll take a look at it once I have some spare time.