Function breakpointhook

crates/vm/src/stdlib/sys.rs:873–922

(args: FuncArgs, vm: &VirtualMachine)

    #[pyfunction(name = "__breakpointhook__")]
    #[pyfunction]
    pub fn breakpointhook(args: FuncArgs, vm: &VirtualMachine) -> PyResult {
        let env_var = std::env::var("PYTHONBREAKPOINT")
            .and_then(|env_var| {
                if env_var.is_empty() {
                    Err(VarError::NotPresent)
                } else {
                    Ok(env_var)
                }
            })
            .unwrap_or_else(|_| "pdb.set_trace".to_owned());

        if env_var.eq("0") {
            return Ok(vm.ctx.none());
        };

        let print_unimportable_module_warn = || {
            warn(
                vm.ctx.exceptions.runtime_warning,
                format!("Ignoring unimportable $PYTHONBREAKPOINT: \"{env_var}\"",),
                0,
                vm,
            )
            .unwrap();
            Ok(vm.ctx.none())
        };

        let last = match env_var.rsplit_once('.') {
            Some((_, last)) => last,
            None if !env_var.is_empty() => env_var.as_str(),
            _ => return print_unimportable_module_warn(),
        };

        let (module_path, attr_name) = if last == env_var {
            ("builtins", env_var.as_str())
        } else {
            (&env_var[..(env_var.len() - last.len() - 1)], last)
        };

        let module = match vm.import(&vm.ctx.new_str(module_path), 0) {
            Ok(module) => module,
            Err(_) => {
                return print_unimportable_module_warn();
            }
        };

        match vm.get_attribute_opt(module, &vm.ctx.new_str(attr_name)) {
            Ok(Some(hook)) => hook.as_ref().call(args, vm),
            _ => print_unimportable_module_warn(),
        }
    }

    #[pyfunction]
    fn exc_info(vm: &VirtualMachine) -> (PyObjectRef, PyObjectRef, PyObjectRef) {