How Can I Skip Values While Using Go\'s iota for Constants?

How to skip values when using iota for constant values?

In Go, when creating a group of constants using iota, you can manually skip values by using the blank identifier _, or by assigning a specific value to a constant and then starting a new group.

Manual Offset

To skip a specific number of values, use the following syntax:

const (
    APPLE = iota
    ORANGE
    PEAR
    _                    // Skip one value
    _                    // Skip another value
    BANANA = 99         // Assign a specific value
    GRAPE                // Continue incrementing iota
)

Breaking the Constant Group

To avoid affecting the values of subsequent constants, break the constant group and start a new one:

const (
    APPLE = iota
    ORANGE
    PEAR
)

const (
    BANANA = iota + 99  // Reset iota to 0 and skip 98 values
    GRAPE                // Continue incrementing iota
)

Automatic Offset

Combine elements of the previous two methods:

const (
    APPLE = iota
    ORANGE
    PEAR

    _BREAK = iota          // Break the group and save the current iota value
    _                    // Skip another value

    BANANA = iota - _BREAK + 98  // Subtract the skipped values from iota
    GRAPE                // Continue incrementing iota
)

This approach allows you to skip a specific number of values while preserving the ordering of subsequent constants.

Recommendation

The best approach depends on the specific requirements:

• Single group, manual offset: When you want to skip a predictable number of values within a group.
• Breaking the constant group: When you want to avoid affecting the values of subsequent constants.
• Single group, automatic offset: For skipping values precisely without breaking the group.

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