https://github.com/megaing/syntax-extensions-base
Base package for syntax-extensions to python
https://github.com/megaing/syntax-extensions-base
Last synced: 25 days ago
JSON representation
Base package for syntax-extensions to python
- Host: GitHub
- URL: https://github.com/megaing/syntax-extensions-base
- Owner: MegaIng
- License: mit
- Created: 2020-12-17T22:57:01.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2021-01-10T20:18:49.000Z (over 5 years ago)
- Last Synced: 2025-09-16T04:46:03.079Z (9 months ago)
- Language: Python
- Size: 16.6 KB
- Stars: 3
- Watchers: 1
- Forks: 0
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# syntax-extensions-base
Base package for syntax-extensions to python
Allows one to use/create custom syntax extensions for python as simple as possible.
## How to get started
First, you need to install this package, this can be done via cloning this repo and running `python -m pip install .` inside of the root folder.
Then you need to select a way of preloading `syntax-extensions` before python runs your code with extensions. This can be done a few ways:
- creating a `sitecustomize.py`/`usercustomize.py` file with the following content: `import syntax_extensions.activate; syntax_extensions.activate.activate_encoding()`
- (This has to be somewhere in your PATH)
- The same line could also be put inside a `.pth` file. Name is irrelevant, but something clear will help (e.g. `syntax_extensions.pth`)
- Needs to be inside `site-packages`
- The line can't be split up.
- Creating an extra `main-wrapper.py` file that first executes the line, and the executes the actual main file.
- Other options will come in the future (most notably, a preloader script that acts like `main-wrapper.py` for any python command)
Now you need to actually write code using this. Here an example:
```
# -*- coding: syntax-extensions -*-
from __syntax_extensions__ import test_base
print(test_base)
```
Note that the first line is important, since it is what tells python to actually let `syntax_extensions` work on the file before it is parsed.
The second line tells `syntax_extensions` what to do. These extensions can be installed separately. At the moment, `test_base` is a very simple package to test that the infrastructure is working. It prints `Transforming...` when it is acting on the code and also adds a `print('test_base')` statement at the end of the file.
If you get an `SyntaxError: encoding problem: syntax-extensions` messages, this (probably) means that `syntax_extensions` isn't correctly preloaded.
## How it works
### Basic structure
`syntax-extensions-base` consists of a few parts:
-`__syntax_extensions__` - A simple module serving a similar purpose as `__future__`: Preventing the default import semantics from complaining about a non-existence module. Also allows one to get some basic info about the extensions.
-`syntax_extensions` - A namespace package, containing a variety of packages
- `.base` The correct implementation: A parser, and a `apply` function (And utils in the future).
- `.activate` A package containing glue code making sure that the extensions are applied. Will contain at least two methods, currently only `encoding` is implemented (and `import` is planned. This will override the default import mechanics)
- `.__main__` Will at some point in the future be the wrapper script, to allow one to execute `python -m syntax_extensions main.py` without having to install some additional preloader.
- `.extensions` Another namespace package. This is where other packages will put their code into.
### How to create your package
Uses this template: (TODO)
In general, you need to create a directory structure of the form `syntax_extensions/extensions/your_extension_name.py` *without* any `__init__.py` files. As long as the parent directory of `syntax_extensions` is in the path, this should already be it. Now you just need to create a `transform` method inside the file that takes a `syntax_extensions.base.parser.Module` instance and transforms it inplace.