RedBaron

0.9.2 · maintenance · verified Tue Apr 14

RedBaron is a Python library built on top of Baron, providing a higher-level abstraction for working with Python source code as a Full Syntax Tree (FST). It aims to simplify tasks like refactoring, code analysis, and programmatic code modification while preserving all syntax information, including comments and formatting. The library is currently at version 0.9.2, with its last release in March 2019, indicating a maintenance or slow development cadence.

Warnings

breaking In version 0.9, the internal structure for annotations changed. Annotations are now members of `DefArgument`, `ListArgument`, and `DictArgument` nodes, and the `TypedNameNode` has been removed. Code directly accessing `TypedNameNode` or expecting the old annotation structure will break.
Fix: Update code to access annotations directly from argument nodes and remove references to `TypedNameNode`.
breaking In version 0.6, `IntNode.value` changed from returning an `int` to a `string`. Use `IntNode.to_python()` for an evaluated integer. Additionally, the `node.find("name")` shortcut now *only* works with possible node identifiers, raising `AttributeError` otherwise.
Fix: Replace `.value` access on `IntNode` with `.to_python()` when an integer is needed. Ensure `node.find()` is used with actual node identifiers or use more general searching methods for other attributes.
gotcha RedBaron operates on a Full Syntax Tree (FST) provided by Baron, which is a lossless representation of the source code. Unlike a traditional Abstract Syntax Tree (AST), an FST preserves all syntax information, including comments, formatting, and whitespace. While this is powerful for refactoring, users accustomed to ASTs should be aware of this difference in tree structure and node properties when navigating and modifying the tree.
Fix: Familiarize yourself with RedBaron's node structure and documentation for FST-specific properties and traversal methods (e.g., `value`, `dumps()`, `fst()`).
gotcha Despite its powerful capabilities, RedBaron is officially considered in 'alpha' status and 'not battle tested yet' according to its documentation. While the public documented API is intended to be retro-compatible until version 2.0, users should be aware that the project's core might still be 'rough' and continued contributions are welcomed.
Fix: Consider its 'alpha' status when planning for production use. Contribute bug reports or fixes to help stabilize the project.

Install

pip install redbaron Basic installation
pip install redbaron[pygments] With syntax highlighting support

Imports

RedBaron
```
from redbaron import RedBaron
```

Quickstart

This quickstart demonstrates how to parse Python code into a RedBaron FST, find a function, modify its name and a variable's value within it, add a new line, and then convert the modified FST back into a Python string. RedBaron's API is designed to be intuitive for tree traversal and modification.

from redbaron import RedBaron

code = """
def my_function(arg1, arg2):
    value = 42
    print(f"Hello {value}")
"""

red = RedBaron(code)

# Find the function definition by name
func_node = red.find("def", name="my_function")

# Change the function name
func_node.name.value = "my_renamed_function"

# Find the variable assignment and change its value
value_assignment_node = func_node.find("assignment", target="value")
if value_assignment_node:
    value_assignment_node.value.value = "99"

# Add a new line (comment) at the end of the function body
# Note: Raw strings might be needed for complex insertions
func_node.value.append("    # Added by RedBaron\n")

# Dump the modified code back to a string
print(red.dumps())

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