tomlrt 0.4.0

A format-preserving TOML parser and writer for Python.

tomlrt

A format-preserving TOML parser and writer for Python.

Usage

import tomlrt

# Files must be opened in binary mode.
with open("pyproject.toml", "rb") as f:
    doc = tomlrt.load(f)

doc["project"]["version"] = "0.2.0"
doc["project"]["dependencies"].append("requests>=2")

print(tomlrt.dumps(doc))   # comments and layout are preserved

Structural assignment

A plain dict value installs as an inline table; a plain list installs as an inline array. To pick a different shape, assign a flavoured value:

from tomlrt import AoT, Array, Table

doc["tool"] = Table.section({"version": 1})      # [tool] section
doc["xy"]   = {"x": 1, "y": 2}                   # xy = { x = 1, y = 2 }
doc["pkgs"] = AoT([{"a": 1}, {"b": 2}])          # [[pkgs]] … [[pkgs]]
doc["tags"] = Array(["a", "b"], multiline=True)  # multi-line array

Use doc.install(path, value) for dotted-path placement. Plain doc["a.b"] = … always treats "a.b" as a single literal key, so install is the way to descend through a into b. Pass a tuple when one of the segments itself contains a literal .:

doc.install("tool.poetry.version", "0.1.0")            # [tool.poetry] version = "0.1.0"
doc.install(("tool", "weird.key"), 1)                  # [tool] "weird.key" = 1

Comment API

doc = tomlrt.loads("""
[server]
host = "localhost"  # default
port = 8080
""")

server = doc.table("server")
server.comments["port"] = "override with $PORT"
server.comments["host"] = None         # clear

print(tomlrt.dumps(doc))
# [server]
# host = "localhost"
# port = 8080 # override with $PORT