inifix

inifix in a small Python library with I/O methods to read and write Pluto/Idefix inifiles as Python dictionaries.

Its primary goal is to support Idefix's model (which is intended as identical to Pluto's), though the following file format specification is intended as a superset of the one used in Pluto and Idefix. Namely, while Pluto and Idefix require that each and every (key, value) pair be part of a section, inifix supports section-free definitions.

File format specifications

• parameter names are strings
• parameter names and values are separated by white spaces
• values can be an integers, floats, booleans, or strings
• a parameter can be associated to a single value or a set of space-separated values
• optionally, the file can be separated into sections, whose names match this regexp "$[\.+]"
• comments start with # and are ignored

Using the following Python's typing notations

from typing import Union, Mapping
Scalar = Union[str, float, bool, int]
InifixConf = Mapping[str, Union[Scalar, Mapping[str, Scalar]]

A configuration file is considered valid if it can be parsed as an InifixConf object.

Examples

The following content is considered valid

# My awesome experiment
[Grid]
x   1 2 "u" 10    # a comment
y   4 5 "l" 100
[Time Integrator]
CFL  1e-3
tstop 1E3

and maps to

{
    "Grid": {
        "x": [1, 2, "u", 10],
        "y": [4, 5, "l", 100]
    },
    "Time Integrator": {
        "CFL": 0.001,
        "tstop": 1000
    }
}

The following is also considered valid

mode   fargo

# Time integrator
CFL    1e-3
tstop  1e3

and maps to

{
    "mode": "fargo",
    "CFL": 0.001,
    "tstop": 1000
}

Note that strings using e-notation (e.g. 1e-3 or 1E3 here) are decoded as numbers. They are cast to int if no precision loss ensues, and float otherwise. Reversly, when writing files, numbers are re-encoded using e-notation if it leads to a more compact representation. For instance, 100000 is encoded as 1e5, but 10 is left unchanged because 1e1 also uses one more character. In case where both reprensations are equally compact (e.g. 100 VS 1e2), e-notation is prefered in encoding.

While decoding, e can be lower or upper case, but they are always encoded as lower case.

Installation

$ pip install inifix

Usage

The API is similar to that of toml and stdlib json, though intentionally simplified, and consists in two main user-facing functions: inifix.load and inifix.dump.

import inifix

# read
conf = inifix.load("pluto.ini")

# patch
conf["Time"]["CFL"] = 0.1

# write back
inifix.dump(conf, "pluto-mod.ini")

inifix.load supports loading from an open file

with open("pluto.ini") as fh:
    conf = inifix.load(fh)

or from a str/os.PathLike object representing a file.

Schema Validation

inifix.validate_inifile_schema can be used to validate an arbitrary dictionary as writable to an inifile, following Pluto/Idefix's format. This will raise an exception (ValueError) if the dictionnary data is invalid.

inifix.validate_inifile_schema(data)

CLI

Command line tool are shipped with the package to validate or format compatible inifiles.

Validation

This checks that your inifiles can be loaded with inifix.load from the command line

$ inifix-validate pluto.ini
Validated pluto.ini

This simple validator can be used as a hook for pre-commit. Simply add the following to your project's .pre-commit-config.yaml

  - repo: https://github.com/neutrinoceros/inifix.git
    rev: v0.9.0
    hooks:
      - id: inifix-validate

Formatting

This will print a formatted verison of the input file to stdout

$ inifix-format pluto.ini

It can be redirected as

$ inifix-format pluto.ini > pluto-formatted.ini

Use the -i/--inplace flag to write back to the source file. Note that comments are preserved in all cases.

This program also doubles as pre-commit hook

  - repo: https://github.com/neutrinoceros/inifix.git
    rev: v0.9.0
    hooks:
      - id: inifix-format

Contribution guidelines

We use the pre-commit framework to automatically lint for code style and common pitfalls.

Before you commit to your local copy of the repo, please run this from the top level

$ python3 -m pip install -u -e .[dev]
$ pre-commit install

Testing

We use the pytest framework to test inifix. The test suite can be run from the top level with a simple pytest invocation.

$ pytest