A CST-based config editor for configparser
This is a module for making automated edits to an existing configparser-compatible ini file. It operates like a CST, parsing into a tree of nodes which can then be edited and written back, preserving whitespace and comments.
test_example_from_readme in the test suite)
Let's say you have the following in
[metadata] # the package name name = imperfect # slurp the readme long_description = file: README.md [options] packages = imperfect
and you'd like to make an edit adding
import difflib import io import imperfect with open("setup.cfg") as f: data = f.read() conf: imperfect.ConfigFile = imperfect.parse_string(data) metadata_section = conf["metadata"] # Ignoring some whitespace for now, this looks like # long_description_content_type = text/markdown\n # [ entry ] # [ key ][eq][ value ] value = imperfect.ValueLine( whitespace_before_text='', text='text/markdown', whitespace_after_text='', newline='\n', ) new_entry = imperfect.ConfigEntry( key="long_description_content_type", equals="=", value = [value], whitespace_before_equals=" ", whitespace_before_value=" ", ) for i, entry in enumerate(metadata_section.entries): if entry.key == "long_description": metadata_section.entries.insert(i+1, new_entry) break buf = io.StringIO() conf.build(buf) print( ''.join( difflib.unified_diff( data.splitlines(True), buf.getvalue().splitlines(True), ) ) ) with open("setup.cfg", "w") as f: f.write(buf.getvalue())
A note on whitespace
Following the convention used by configobj, whitespace generally is accumulated and stored on the node that follows it. This does reasonably well for adding entries, but can have unexpected consequences when removing them. For example,
[section1] # this belongs to k1 k1 = foo # this belongs to k2 k2 = foo # k3 = foo (actually belongs to the following section) [section2]
An insertion to the end of
section1 would go between k2 and the k3 comment.
section2 would also remove the commented-out
I'm open to ideas that improve this.
A note on formats
The goal is to be as compatible as possible with
includes keeping some odd behaviors that are bugs that have been around for a
decade and probably can't be changed now.
- Section names are very lenient.
[[x]]yyis a legal section line, and the resulting section name is
yyhere is always allowed (we keep it in the tree though), even with
\r(carriage return) is considered a whitespace, but not a line terminator. This is a difference in behavior between
list(io)-- configparser uses the latter.
\tcounts as single whitespace.
Supported parse options
Option Default Imperfect supports allow_no_value False only False delimiters =,: only =,: comment_prefixes #,; only #,; empty_lines_in_values True True (False is very close to working)
We use hypothesis to generate plausible ini files and for all the ones that RawConfigParser can accept, we test that we accept, have the same keys/values, and can roundtrip it.
This currently happens in text mode only.
If you would like to test support on your file, try
python -m imperfect.verify <filename>
configobjhas a completely different method for line continuations
- I'm not aware of others with the goal of preserving whitespace
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