Enum GetResult 

pub enum GetResult {
    Value(Value),
    NoSuchObject,
    NoSuchInstance,
}

Result of a GET operation on a specific OID (RFC 3416).

This enum distinguishes between the RFC 3416-mandated exception types:

• Value: The OID exists and has the given value
• NoSuchObject: The OID’s object type is not supported (agent doesn’t implement this MIB)
• NoSuchInstance: The object type exists but this specific instance doesn’t (e.g., table row doesn’t exist)

Version Differences

• SNMPv1: Both exception types result in a noSuchName error response
• SNMPv2c/v3: Returns the appropriate exception value in the response varbind

Choosing NoSuchObject vs NoSuchInstance

Situation	Variant
OID prefix not recognized	NoSuchObject
Scalar object not implemented	NoSuchObject
Table column not implemented	NoSuchObject
Table row doesn’t exist	NoSuchInstance
Scalar has no value (optional)	NoSuchInstance

Example: Scalar Objects

use async_snmp::handler::GetResult;
use async_snmp::{Value, oid};

fn get_scalar(oid: &async_snmp::Oid) -> GetResult {
    if oid == &oid!(1, 3, 6, 1, 2, 1, 1, 1, 0) {  // sysDescr.0
        GetResult::Value(Value::OctetString("My SNMP Agent".into()))
    } else if oid == &oid!(1, 3, 6, 1, 2, 1, 1, 2, 0) {  // sysObjectID.0
        GetResult::Value(Value::ObjectIdentifier(oid!(1, 3, 6, 1, 4, 1, 99999)))
    } else {
        GetResult::NoSuchObject
    }
}

Example: Table Objects

use async_snmp::handler::GetResult;
use async_snmp::{Value, Oid, oid};

struct IfTable {
    entries: Vec<(u32, String)>,  // (index, description)
}

impl IfTable {
    fn get(&self, oid: &Oid) -> GetResult {
        let if_descr_prefix = oid!(1, 3, 6, 1, 2, 1, 2, 2, 1, 2);

        if !oid.starts_with(&if_descr_prefix) {
            return GetResult::NoSuchObject;  // Not our column
        }

        // Extract index from OID (position after prefix)
        let arcs = oid.arcs();
        if arcs.len() != if_descr_prefix.len() + 1 {
            return GetResult::NoSuchInstance;  // Wrong index format
        }

        let index = arcs[if_descr_prefix.len()];
        match self.entries.iter().find(|(i, _)| *i == index) {
            Some((_, desc)) => GetResult::Value(Value::OctetString(desc.clone().into())),
            None => GetResult::NoSuchInstance,  // Row doesn't exist
        }
    }
}

Variants

Value(Value)

The OID exists and has this value.

NoSuchObject

The object type is not implemented by this agent.

Use this when the OID prefix (object type) is not recognized. This typically means the handler doesn’t implement this part of the MIB.

NoSuchInstance

The object type exists but this specific instance doesn’t.

Use this when the OID prefix is valid but the instance identifier (e.g., table index) doesn’t exist. This is common for table objects where the row has been deleted or never existed.

Implementations

impl GetResult

pub fn from_option(value: Option<Value>) -> Self

Create a GetResult from an Option<Value>.

This is a convenience method for migrating from the previous Option<Value> interface. None is treated as NoSuchObject.

Trait Implementations

impl Clone for GetResult

fn clone(&self) -> GetResult

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for GetResult

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl From<Option<Value>> for GetResult

fn from(value: Option<Value>) -> Self

Converts to this type from the input type.

impl From<Value> for GetResult

fn from(value: Value) -> Self

Converts to this type from the input type.

impl PartialEq for GetResult

fn eq(&self, other: &GetResult) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for GetResult