| :orphan: | |
| .. _vision: | |
| ******************************************** | |
| Vision for a Common Astronomy Python Package | |
| ******************************************** | |
| The following document summarizes a vision for a common Astronomy Python | |
| package, and how we can best all work together to achieve this. In the | |
| following document, this common package will be referred to as the core | |
| package. This vision is not set in stone, and we are committed to adapting it | |
| to whatever process and guidelines work in practice. | |
| The ultimate goal that we seek is a package that would contain much of the core | |
| functionality and some common tools required across Astronomy, but not | |
| *everything* Astronomers will ever need. The aim is primarily to avoid | |
| duplication for common core tasks, and to provide a robust framework upon which | |
| to build more complex tools. | |
| Such a common package should not preclude any other Astronomy package from | |
| existing, because there will always be more complex and/or specialized tools | |
| required. These tools will be able to rely on a single core library for many | |
| tasks, and thus reduce the number of dependencies, reduce duplication of | |
| functionality, and increase consistency of their interfaces. | |
| Procedure | |
| ========= | |
| With the help of the community, the coordination committee will start by | |
| identifying a few of key areas where initial development/consolidation will be | |
| needed (such as FITS, WCS, coordinates, tables, photometry, spectra, etc.) and | |
| will encourage teams to be formed to build standalone packages implementing | |
| this functionality. These packages will be referred to as affiliated packages | |
| (meaning that they are intended for future integration in the core package). | |
| A set of requirements will be set out concerning the interfaces and | |
| classes/methods that affiliated packages will need to make available in order | |
| to ensure consistency between the different components. As the core package | |
| grows, new potential areas/components for the core package will be identified. | |
| Competition cannot be avoided, and will not be actively discouraged, but | |
| whenever possible, developers should strive to work as a team to provide a | |
| single and robust affiliated package, for the benefit of the community. | |
| The affiliated packages will be developed outside the core package in | |
| independent repositories, which will allow the teams the choice of tool and | |
| organization. Once an affiliated package has implemented the desired | |
| functionality, and satisfies quality criteria for coding style, documentation, | |
| and testing, it will be considered for inclusion in the core package, and | |
| further development will be done directly in the core package either via direct | |
| access to the repository, or via patches/pull requests (exactly how this will | |
| be done will be decided later). | |
| To ensure uniformity across affiliated packages, and to facilitate integration | |
| with the core package, developers who wish to submit their affiliated packages | |
| for inclusion in the core will need to follow the layout of a ‘template’ | |
| package that will be provided before development starts. | |
| Dependencies | |
| ============ | |
| Affiliated packages should be able to be imported with only the following | |
| dependencies: | |
| * The Python Standard Library NumPy, SciPy, and Matplotlib Components already | |
| * in the core Astronomy package | |
| Other packages may be used, but must be imported as needed rather than during | |
| the initial import of the package. | |
| If a dependency is needed, but is an affiliated package, the dependent package | |
| will need to wait until the dependency is integrated into the core package | |
| before being itself considered for inclusion. In the mean time, it can make use | |
| of the other affiliated package in its current form, or other packages, so as | |
| not to stall development. Thus, the first packages to be included in the core | |
| will be those only requiring the standard library, NumPy, SciPy, and | |
| Matplotlib. | |
| If the required dependency will never be part of a main package, then by | |
| default the dependency can be included but should be imported as needed | |
| (meaning that it only prevents the importing of that component, not the entire | |
| core package), unless a strong case is made and a general consensus is reached | |
| by the community that this dependency is important enough to be required at a | |
| higher level. | |
| This system means that packages will be integrated into the core package in an | |
| order depending on the dependency tree, and also ensures that the interfaces of | |
| packages being integrated into the core package are consistent with those | |
| already in the core package. | |
| Initially, no dependency on GUI toolkits will be allowed in the core package. | |
| If the community reaches agrees on a single toolkit that could be used, then | |
| this toolkit will be allowed (but will only be imported as needed). | |
| Keeping track of affiliated packages | |
| ==================================== | |
| Affiliated packages will be listed in a central location (in addition to PyPI) | |
| that will allow an easy installation of all the affiliated packages, for | |
| example with a script that will seamlessly download and install all the | |
| affiliated packages. The core package will also include mechanisms to | |
| facilitate this installation process. | |
| Existing Packages | |
| ================= | |
| Developers who already have existing packages will be encouraged to continue | |
| supporting them for the benefit of users until the core library is considered | |
| stable, contains this functionality, and is released to the community. | |
| Thereafter, developers should encourage users to transition to using the | |
| functionality in the core package, and eventually phase out their own packages, | |
| unless they provide added value over the core package. | |