SamplePythonToolbox

Sample ArcGIS Pro Python Toolbox

Testing distributing geoprocessing toolboxes with Python modules and how to build on GitHub.

Line Length

Line length needs to be consistently configured for formatting, linting and while sorting imports. In order to change the line length for a specific project, it will need to be updated in the following locations:

• .pylintrc
• pyproject.toml

Formatting

Formatting is handled by black.

Black is an uncompromising Python code formatting tool. It takes a Python file as an input, and provides a reformatted Python file as an output, using rules that are a strict subset of PEP 8. It offers very little in the way of configuration (line length being the main exception) in order to achieve formatting consistency. It is deterministic - it will always produce the same output from the same inputs.

The line length configuration is stored in pyproject.toml.

Configuring Black to automatically run every time code is modified allows developers to forget about how code should be formatted and stay focused on functionality. Many IDEs and text editors allow this. Git hooks can also be used to execute Black before Python code is committed to a repository - this is not configured here as use of autosave and continuous integration checks makes it redundant.

VSCode Configuration

In VSCode, you can set the default Python formatter using the setting: "python.formatting.provider": "black", and then turn on autosave using "editor.formatOnSave": true. VSCode will pick up the line length configuration from a pyproject.toml file per repository.

Sorting Imports

Import sorting is handled by isort.

isort sorts Python imports alphabetically within their respective sections:

1. Standard library imports
2. Related third party imports
3. Local application / library specific imports

isort has many configuration options but these can cause inconsistencies with Black, so must be carefully assessed. The configurations within this repository will provide consistently ordered / formatted imports.

The configuration is stored in pyproject.toml.

VSCode Configuration

VSCode will pick up the isort configuration from a pyproject.toml file per repository. It is possible to configure VSCode to run isort every time you save, using the codeActionsOnSave": { "source.organizeImports": true } setting. This currently causes a race condition when formatting by black is also configured to occur on save ("editor.formatOnSave": true), leading to lines being erroneously deleted. The VSCode Python team can't do anything about this.

The configuration stored here works with black - that is to say, black will not reformat changes made by isort - but it is still unsafe to apply both commands simultaneously.

In VSCode, you can manually trigger import sorting by:

• right clicking anywhere within a file and selecting Sort Imports.
• command palette (Ctrl + Shift + P), then Python Refactor: Sort Imports.
• creating a shortcut key for python.sortImports

Linting

Linting is handled by pylint.

Pylint checks Python files in order to detect syntax errors and potential bugs (unreachable code / unused variables), provide refactoring help,

The configuration is stored in .pylintrc.