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FAQ Why is the dependency resolution process slow? While the dependency resolver at the heart of Poetry is highly optimized and should be fast enough for most cases, with certain sets of dependencies it can take time to find a valid solution. This is due to the fact that not all libraries on PyPI have properly declared their metadata and, as such, they are not available via the PyPI JSON API. At this point, Poetry has no choice but to download the packages and inspect them to get the necessary information. This is an expensive operation, both in bandwidth and time, which is why it seems this is a long process.

pre-commit hooks pre-commit is a framework for building and running git hooks. See the official documentation for more information: pre-commit.com This document provides a list of available pre-commit hooks provided by Poetry. Note If you specify the args: for a hook in your .pre-commit-config.yaml, the defaults are overwritten. You must fully specify all arguments for your hook if you make use of args:. Note If the pyproject.toml file is not in the root directory, you can specify args: ["-C", "./subdirectory"]. poetry-check The poetry-check hook calls the poetry check command to make sure the poetry configuration does not get committed in a broken state.

Introduction Poetry is a tool for dependency management and packaging in Python. It allows you to declare the libraries your project depends on and it will manage (install/update) them for you. Poetry offers a lockfile to ensure repeatable installs, and can build your project for distribution. System requirements Poetry requires Python 3.9+. It is multi-platform and the goal is to make it work equally well on Linux, macOS and Windows.

Libraries This chapter will tell you how to make your library installable through Poetry. Versioning Poetry requires PEP 440-compliant versions for all projects. While Poetry does not enforce any release convention, it used to encourage the use of semantic versioning within the scope of PEP 440 and supports version constraints that are especially suitable for semver. Note As an example, 1.0.0-hotfix.1 is not compatible with PEP 440. You can instead choose to use 1.0.0-post1 or 1.0.0.post1. Lock file For your library, you may commit the poetry.lock file if you want to. This can help your team to always test against the same dependency versions. However, this lock file will not have any effect on other projects that depend on it. It only has an effect on the main project.

Configuration Poetry can be configured via the config command (see more about its usage here) or directly in the config.toml file that will be automatically created when you first run that command. This file can typically be found in one of the following directories: macOS: ~/Library/Application Support/pypoetry Windows: %APPDATA%\pypoetry For Unix, we follow the XDG spec and support $XDG_CONFIG_HOME. That means, by default ~/.config/pypoetry. Local configuration Poetry also provides the ability to have settings that are specific to a project by passing the --local option to the config command.

Managing environments Poetry makes project environment isolation one of its core features. What this means is that it will always work isolated from your global Python installation. To achieve this, it will first check if it’s currently running inside a virtual environment. If it is, it will use it directly without creating a new one. But if it’s not, it will use one that it has already created or create a brand new one for you.

Basic usage For the basic usage introduction we will be installing pendulum, a datetime library. If you have not yet installed Poetry, refer to the Introduction chapter. Project setup First, let’s create our new project, let’s call it poetry-demo: poetry new poetry-demo This will create the poetry-demo directory with the following content: poetry-demo ├── pyproject.toml ├── README.md ├── src │ └── poetry_demo │ └── __init__.py └── tests └── __init__.py The pyproject.toml file is what is the most important here. This will orchestrate your project and its dependencies. For now, it looks like this:

pre-commit hooks pre-commit is a framework for building and running git hooks. See the official documentation for more information: pre-commit.com This document provides a list of available pre-commit hooks provided by Poetry. Note If you specify the args: for a hook in your .pre-commit-config.yaml, the defaults are overwritten. You must fully specify all arguments for your hook if you make use of args:. Note If the pyproject.toml file is not in the root directory, you can specify args: ["-C", "./subdirectory"]. poetry-check The poetry-check hook calls the poetry check command to make sure the poetry configuration does not get committed in a broken state.

Dependency specification Dependencies for a project can be specified in various forms, which depend on the type of the dependency and on the optional constraints that might be needed for it to be installed. Version constraints Caret requirements Caret requirements allow SemVer compatible updates to a specified version. An update is allowed if the new version number does not modify the left-most non-zero digit in the major, minor, patch grouping. For instance, if we previously ran poetry add requests@^2.13.0 and wanted to update the library and ran poetry update requests, poetry would update us to version 2.14.0 if it was available, but would not update us to 3.0.0. If instead we had specified the version string as ^0.1.13, poetry would update to 0.1.14 but not 0.2.0. 0.0.x is not considered compatible with any other version.