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remove pipenv comparison #5561

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remove pipenv comparison #5561

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66 changes: 0 additions & 66 deletions README.md
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Expand Up @@ -97,72 +97,6 @@ It takes inspiration in tools that exist in other languages, like `composer` (PH
And, finally, I started `poetry` to bring another exhaustive dependency resolver to the Python community apart from
[Conda's](https://conda.io).

### What about Pipenv?

In short: I do not like the CLI it provides, or some of the decisions made,
and I think we can make a better and more intuitive one. Here are a few things
that I don't like.

#### Dependency resolution

The dependency resolution is erratic and will fail even if there is a solution. Let's take an example:

```bash
pipenv install oslo.utils==1.4.0
```

will fail with this error:

```text
Could not find a version that matches pbr!=0.7,!=2.1.0,<1.0,>=0.6,>=2.0.0
```

while Poetry will get you the right set of packages:

```bash
poetry add oslo.utils=1.4.0
```

results in :

```text
- Installing pytz (2018.3)
- Installing netifaces (0.10.6)
- Installing netaddr (0.7.19)
- Installing oslo.i18n (2.1.0)
- Installing iso8601 (0.1.12)
- Installing six (1.11.0)
- Installing babel (2.5.3)
- Installing pbr (0.11.1)
- Installing oslo.utils (1.4.0)
```

This is possible thanks to the efficient dependency resolver at the heart of Poetry.

Here is a breakdown of what exactly happens here:

`oslo.utils (1.4.0)` depends on:

- `pbr (>=0.6,!=0.7,<1.0)`
- `Babel (>=1.3)`
- `six (>=1.9.0)`
- `iso8601 (>=0.1.9)`
- `oslo.i18n (>=1.3.0)`
- `netaddr (>=0.7.12)`
- `netifaces (>=0.10.4)`

What interests us is `pbr (>=0.6,!=0.7,<1.0)`.

At this point, poetry will choose `pbr==0.11.1` which is the latest version that matches the constraint.

Next it will try to select `oslo.i18n==3.20.0` which is the latest version that matches `oslo.i18n (>=1.3.0)`.

However this version requires `pbr (!=2.1.0,>=2.0.0)` which is incompatible with `pbr==0.11.1`,
so `poetry` will try to find a version of `oslo.i18n` that satisfies `pbr (>=0.6,!=0.7,<1.0)`.

By analyzing the releases of `oslo.i18n`, it will find `oslo.i18n==2.1.0` which requires `pbr (>=0.11,<2.0)`.
At this point the rest of the resolution is straightforward since there is no more conflict.

## Resources

* [Official Website](https://python-poetry.org)
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