lvconfig

Typed reader and writer for LabVIEW configuration files, with LabVIEW-correct escaping, path and boolean rules.

Install

pip install lvconfig

Usage

import lvconfig

text = """
; rig configuration
[General]
name = "Rig \\22A\\22"
enabled = TRUE
retries = 3

[Paths]
log = "/C/Temp/log.txt"
"""

config = lvconfig.parse(text)

config.get_str("General", "name")      # 'Rig "A"'   (quotes decoded from \22)
config.get_bool("General", "enabled")  # True
config.get_int("General", "retries")   # 3
config.get_path("Paths", "log")        # 'C:\\Temp\\log.txt'

# Build and write a file LabVIEW reads back correctly.
out = lvconfig.Config()
out.set("General", "name", 'Rig "A"\r')            # quoted and escaped on dump
out.set("General", "enabled", True)                # written as TRUE, not "True"
out.set_path("Paths", "log", r"C:\Temp\log.txt")   # stored as /C/Temp/log.txt
print(lvconfig.dump(out))

Read and write files directly with load and save. save uses the CRLF line endings LabVIEW writes on Windows:

config = lvconfig.load("settings.ini")
config.set("General", "retries", 5)
lvconfig.save(config, "settings.ini")

Comments survive a round-trip. parse keeps every whole-line ; comment and attaches it to the section or key below it, and dump writes it back. Config also offers items, to_dict, remove and remove_section.

Low-level helpers are public too: escape/unescape for the \XX codes, to_labview_path/from_labview_path for the stored path form, and to_bool/to_int/to_float for value coercion.

Command line

Installing the package puts an lvconfig command on the path:

lvconfig json settings.ini                         # dump the file as decoded JSON
lvconfig json settings.ini --section General        # only one section
lvconfig get settings.ini General enabled --type bool
lvconfig get settings.ini Paths log --type path     # prints C:\Temp\log.txt
lvconfig convert plain.ini labview.ini              # plain .ini to LabVIEW-escaped form

convert reads a plain INI (the kind configparser writes), infers booleans and numbers, and writes it back with LabVIEW escaping, quoting and path form. Run lvconfig --help for the full list with examples.

Escaping rules it handles

• \XX hex codes for control and non-displayable characters (a carriage return is \0D, a tab is \09), decoded on read and re-encoded on write with uppercase digits.
• Doubled backslashes: a literal backslash is stored as \\.
• Quoted strings: string and path values are wrapped in double quotes to protect surrounding whitespace, and the quotes come off on read.
• Stored paths: the drive letter moves after a leading slash and separators become forward slashes, so C:\Temp\log.txt is stored as /C/Temp/log.txt; UNC paths keep a leading //.
• Booleans as TRUE/FALSE, with 1/0 also read as booleans.

Why

LabVIEW's "Configuration File" format looks like an INI file but is not one. LabVIEW's own Configuration File VIs, and the OpenG Variant Configuration File library on top of them, encode control characters as \XX hex codes (a carriage return is \0D), double literal backslashes, wrap string and path values in quotation marks to protect whitespace, store paths in a platform-neutral form with the drive after a leading slash (C:\Temp becomes /C/Temp), and write booleans as TRUE or FALSE. These rules are described in NI's Windows configuration settings file format documentation. All of that runs inside LabVIEW; none of it helps a Python process with no LabVIEW present.

Python's standard-library configparser honours none of them: it does not decode \XX escapes, treats backslashes literally, keeps the surrounding quotation marks as part of the value, and leaves /C/Temp as a broken path. The result is a corrupted read and a file LabVIEW cannot load back. This is a long-standing pain point in the NI community (for example the "ConfigFile Read Key" doubled-backslash reports on forums.ni.com), and at the time of writing no maintained PyPI package implements these semantics: the available INI parsers (configparser, iniparse, iniparser2) are all generic and share the same gap.

lvconfig reads and writes the format exactly as LabVIEW does, round-trips losslessly, and coerces each value to the Python type it stands for. It is pure standard library, fully typed, and ships py.typed.

License

MIT. See LICENSE.

Links

• Website: https://lianes8studio.com
• GitHub: https://github.com/JaviLianes8
• LinkedIn: https://www.linkedin.com/in/jlianes/