> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sourcery.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Compare Via Equals

#### Sourcery refactoring id: `compare-via-equals`

#### Description

Use == or != to compare str, bytes, int, and float.

#### Before

```python
nr = 100
if nr is calculate_sum():
    do_x()
```

#### After

```python
nr = 100
if nr == calculate_sum():
    do_x()
```

#### Before

```python
if calculate_sum() is not 100:
    do_x()
```

#### After

```python
if calculate_sum() != 100:
    do_x()
```

#### Explanation

While `is` compares whether two objects are the same, `==` compares whether
their values are the same. For objects without an identity (aka value objects in
domain-driven design), only the comparison of their values make sense. Prefer
`==` to `is` both for the built-in value object types, but also for the value
objects defined in your code.

Comparing the built-in number types via `is` can also lead to some surprising
behaviour and bugs. For small numbers, `is` returns the same as `==`:

```
nr = 42
other_nr = 42
nr == other_nr
=> True
nr is other_nr
=> True
```

For huge numbers, the result is different:

```
nr = 42000
other_nr = 42000
nr == other_nr
=> True
nr is other_nr
=> False
```

The same applies for `is not` vs `!=`.