Stack Data

0.6.3 · active · verified Sat Mar 28

stack-data is a Python library designed to extract detailed information from stack frames and tracebacks, offering more useful and customizable displays than Python's default tracebacks. It's currently at version 0.6.3 and is actively maintained, powering features in tools like IPython and futurecoder.

Warnings

gotcha When inspecting recursive functions or deeply nested calls, `stack_data`, similar to Python's built-in traceback, automatically avoids showing all identical repeated frames. It instead provides a `RepeatedFrames` object. If you need to see every single frame, you must explicitly pass `collapse_repeated_frames=False` to `FrameInfo` (not to `Options`).
Fix: Pass `collapse_repeated_frames=False` to `stack_data.FrameInfo` when initializing, e.g., `stack_data.FrameInfo(frame, collapse_repeated_frames=False)`.
gotcha When rendering lines that include markers (e.g., for highlighting or inserting HTML), ensure you use `line.render(markers, escape_html=True)` if you are inserting HTML. This will correctly escape special HTML characters in the Python source code to prevent malformed output, while still allowing your markers to be interpreted as HTML.
Fix: Use `line.render(markers, escape_html=True)` when preparing output for HTML display, especially if markers themselves contain unescaped HTML.
gotcha The basic `line.render()` method strips common leading indentation. If preserving exact original indentation (including common leading whitespace) is critical for your display logic, be aware that `line.render()` modifies it. More advanced control over rendering and ranges is available via `line.token_ranges` or `line.range_from_node`.
Fix: For custom indentation control, consider iterating through `line.token_ranges` and reconstructing the line, or use `line.range_from_node(node, data)` for more granular control over specific parts of the line.

Install

pip install stack-data Install with pip

Imports

FrameInfo
```
from stack_data import FrameInfo
```
Options
```
from stack_data import Options
```
Line
```
from stack_data import Line
```

Quickstart

This example demonstrates basic usage by creating a FrameInfo object from the current frame and then iterating through its lines to print the source code, highlighting the current line.

import inspect
import stack_data

def foo():
    result = []
    for i in range(2):
        row = []
        result.append(row)
        print_stack()
        for j in range(2):
            row.append(i * j)
    return result

def print_stack():
    frame = inspect.currentframe().f_back
    frame_info = stack_data.FrameInfo(frame)
    print(f"{frame_info.code.co_name} at line {frame_info.lineno}")
    print("-----------")
    for line in frame_info.lines:
        print(f"{'-->' if line.is_current else ' '} {line.lineno:4} | {line.render()}")

foo()

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