boltons_quickstart_omd_remap_traceback_research_utilities.py

1from boltons.iterutils import remap
2from boltons.dictutils import OMD
3from boltons.tbutils import TracebackInfo
4
5# 1. OrderedMultiDict (OMD) - A dictionary that allows multiple values per key
6# and maintains order, perfect for query strings or headers.
7omd = OMD([('a', 1), ('b', 2), ('a', 3)])
8omd.add('b', 4)
9print(f"OMD values for 'a': {omd.getlist('a')}")  # [1, 3]
10print(f"OMD as dict: {omd.to_dict()}")           # {'a': 3, 'b': 4}
11
12# 2. Remap - A powerful tool for transforming nested data structures
13data = {'a': 1, 'b': {'c': 2, 'd': [3, 4]}}
14# Increment every integer in a nested structure
15visit = lambda path, key, value: (key, value + 1) if isinstance(value, int) else (key, value)
16remapped = remap(data, visit=visit)
17print(f"Remapped data: {remapped}")  # {'a': 2, 'b': {'c': 3, 'd': [4, 5]}}
18
19# 3. TracebackInfo - Simplified, object-oriented access to exception tracebacks
20try:
21    x = 1 / 0
22except Exception:
23    ti = TracebackInfo.from_current()
24    print(f"Error caught in function: {ti.frames[-1].name}")
25    print(f"Line content: {ti.frames[-1].line.strip()}")
26
27# 4. Breadcrumbs - Easily see where you are in a nested structure during iteration
28from boltons.iterutils import research
29
30target_data = {'users': [{'id': 1, 'name': 'Alice'}, {'id': 2, 'name': 'Bob'}]}
31# Find the path to the value 'Bob'
32matches = research(target_data, query=lambda p, k, v: v == 'Bob')
33print(f"Path to Bob: {matches[0][0]}") # ('users', 1, 'name')