Regex Configuration Patterns

Generates the correct regex patterns for config_manager.py save operations that update BobConfig.py.

When to Use

Adding save logic to config_manager.py
Creating regex patterns for new config parameters
Troubleshooting regex matching issues
Understanding the config save pattern

Pattern Structure

All config saves follow this pattern:

python

content = re.sub(
    r'PATTERN_TO_MATCH',
    f'REPLACEMENT_STRING',
    content
)
changes_made.append(f"PARAM_NAME = {value}")

Type-Specific Patterns

Boolean Parameters

BobConfig.py:

python

FEATURE_ENABLED: bool = True

Regex Pattern:

python

if 'feature_enabled' in section:
    content = re.sub(
        r'FEATURE_ENABLED:\s*bool\s*=\s*(True|False)',
        f'FEATURE_ENABLED: bool = {section["feature_enabled"]}',
        content
    )
    changes_made.append(f"FEATURE_ENABLED = {section['feature_enabled']}")

Pattern Breakdown:

FEATURE_ENABLED: - Exact parameter name + colon
\s* - Zero or more whitespace
bool - Type annotation
\s*=\s* - Equals sign with optional whitespace
(True|False) - Either True or False (capture group)

Integer Parameters

BobConfig.py:

python

MAX_RETRIES: int = 3

Regex Pattern:

python

if 'max_retries' in section:
    content = re.sub(
        r'MAX_RETRIES:\s*int\s*=\s*\d+',
        f'MAX_RETRIES: int = {section["max_retries"]}',
        content
    )
    changes_made.append(f"MAX_RETRIES = {section['max_retries']}")

Pattern Breakdown:

\d+ - One or more digits (matches any integer)

Float Parameters

BobConfig.py:

python

THRESHOLD: float = 0.5
PERCENTAGE: float = 10.0

Regex Pattern:

python

if 'threshold' in section:
    content = re.sub(
        r'THRESHOLD:\s*float\s*=\s*[\d.]+',
        f'THRESHOLD: float = {float(section["threshold"])}',
        content
    )
    changes_made.append(f"THRESHOLD = {section['threshold']}")

Pattern Breakdown:

[\d.]+ - One or more digits or decimal points
Note: float() conversion in f-string ensures proper formatting

Important: Always cast to float in f-string!

python

# ✓ Correct
f'THRESHOLD: float = {float(section["threshold"])}'

# ✗ Wrong - may produce "0.5" vs "0.50"
f'THRESHOLD: float = {section["threshold"]}'

String Parameters

BobConfig.py:

python

MODEL_NAME: str = "default"
API_URL: str = "http://localhost:5000"

Regex Pattern:

python

if 'model_name' in section:
    content = re.sub(
        r'MODEL_NAME:\s*str\s*=\s*"[^"]*"',
        f'MODEL_NAME: str = "{section["model_name"]}"',
        content
    )
    changes_made.append(f"MODEL_NAME = {section['model_name']}")

Pattern Breakdown:

"[^"]*" - Matches string in double quotes
[^"] - Any character except double quote
* - Zero or more characters

For single quotes:

python

r"MODEL_NAME:\s*str\s*=\s*'[^']*'"
f"MODEL_NAME: str = '{section[\"model_name\"]}'"

Optional Parameters

BobConfig.py:

python

API_KEY: Optional[str] = None

Regex Pattern:

python

if 'api_key' in section:
    content = re.sub(
        r'API_KEY:\s*Optional\[str\]\s*=\s*(?:"[^"]*"|None)',
        f'API_KEY: Optional[str] = "{section["api_key"]}" if section["api_key"] else "None"',
        content
    )
    changes_made.append(f"API_KEY = {section['api_key']}")

Pattern Breakdown:

Optional\[str\] - Type annotation (brackets escaped)
(?:"[^"]*"|None) - Non-capturing group: either string or None
"[^"]*" - String in quotes
| - OR
None - Literal None

List Parameters

BobConfig.py:

python

ALLOWED_MODELS: List[str] = ["model1", "model2"]

Regex Pattern (Complex):

python

if 'allowed_models' in section:
    models_str = str(section["allowed_models"])  # Convert list to string
    content = re.sub(
        r'ALLOWED_MODELS:\s*List\[str\]\s*=\s*\[.*?\]',
        f'ALLOWED_MODELS: List[str] = {models_str}',
        content
    )
    changes_made.append(f"ALLOWED_MODELS = {len(section['allowed_models'])} items")

Pattern Breakdown:

\[.*?\] - Matches list brackets with any content
.*? - Non-greedy match (minimum characters)

Common Pattern Variations

With Comments

BobConfig.py:

python

MAX_FPS: int = 30  # Maximum frames per second

Regex (preserves comment):

python

r'MAX_FPS:\s*int\s*=\s*\d+(\s*#.*)?'

Pattern Breakdown:

(\s*#.*)? - Optional group for comment
\s*# - Whitespace + hash
.* - Rest of comment
? - Group is optional

Multiline Parameters

BobConfig.py:

python

LONG_LIST: List[str] = [
    "item1",
    "item2"
]

Use re.DOTALL flag:

python

content = re.sub(
    r'LONG_LIST:\s*List\[str\]\s*=\s*\[.*?\]',
    f'LONG_LIST: List[str] = {value}',
    content,
    flags=re.DOTALL
)

Complete Save Method Template

python

def save_<section>_settings(self, settings: Dict) -> Dict:
    """Save <section> settings to BobConfig.py"""
    try:
        config_path = Path(__file__).parent.parent / 'BobConfig.py'

        if not config_path.exists():
            return {'success': False, 'message': f'Config file not found: {config_path}'}

        # Read current config
        with open(config_path, 'r', encoding='utf-8') as f:
            content = f.read()

        changes_made = []

        # Boolean parameter
        if 'bool_param' in settings['section']:
            content = re.sub(
                r'BOOL_PARAM:\s*bool\s*=\s*(True|False)',
                f'BOOL_PARAM: bool = {settings["section"]["bool_param"]}',
                content
            )
            changes_made.append(f"BOOL_PARAM = {settings['section']['bool_param']}")

        # Integer parameter
        if 'int_param' in settings['section']:
            content = re.sub(
                r'INT_PARAM:\s*int\s*=\s*\d+',
                f'INT_PARAM: int = {settings["section"]["int_param"]}',
                content
            )
            changes_made.append(f"INT_PARAM = {settings['section']['int_param']}")

        # Float parameter
        if 'float_param' in settings['section']:
            content = re.sub(
                r'FLOAT_PARAM:\s*float\s*=\s*[\d.]+',
                f'FLOAT_PARAM: float = {float(settings["section"]["float_param"])}',
                content
            )
            changes_made.append(f"FLOAT_PARAM = {settings['section']['float_param']}")

        # String parameter
        if 'str_param' in settings['section']:
            content = re.sub(
                r'STR_PARAM:\s*str\s*=\s*"[^"]*"',
                f'STR_PARAM: str = "{settings["section"]["str_param"]}"',
                content
            )
            changes_made.append(f"STR_PARAM = {settings['section']['str_param']}")

        if not changes_made:
            return {'success': False, 'message': 'No valid settings to update'}

        # Write updated config
        with open(config_path, 'w', encoding='utf-8') as f:
            f.write(content)

        logger.info(f"Updated settings: {', '.join(changes_made)}")

        return {
            'success': True,
            'message': f'Settings saved. Updated: {", ".join(changes_made)}'
        }

    except Exception as e:
        logger.error(f"Error saving settings: {e}", exc_info=True)
        return {'success': False, 'message': f'Error: {str(e)}'}

Testing Regex Patterns

Python REPL Test:

python

import re

# Test content
content = "THRESHOLD: float = 0.5  # Detection threshold"

# Test pattern
pattern = r'THRESHOLD:\s*float\s*=\s*[\d.]+'
replacement = f'THRESHOLD: float = {float(10.0)}'

result = re.sub(pattern, replacement, content)
print(result)
# Output: THRESHOLD: float = 10.0  # Detection threshold

Online Regex Tester:

https://regex101.com/ (Python flavor)
Paste BobConfig.py line
Test pattern
Verify match and replacement

Common Mistakes

1. Wrong Pattern for Float

python

# ✗ Wrong - only matches integers
r'THRESHOLD:\s*float\s*=\s*\d+'

# ✓ Correct - matches floats with decimals
r'THRESHOLD:\s*float\s*=\s*[\d.]+'

2. Missing Float Conversion

python

# ✗ Wrong - may lose precision
f'THRESHOLD: float = {value}'

# ✓ Correct - explicit float conversion
f'THRESHOLD: float = {float(value)}'

3. Greedy vs Non-Greedy

python

# ✗ Wrong - matches too much (greedy)
r'PARAM:\s*str\s*=\s*".*"'  # Matches from first to LAST quote

# ✓ Correct - matches minimal (non-greedy)
r'PARAM:\s*str\s*=\s*"[^"]*"'  # Matches one string

4. Not Escaping Special Characters

python

# ✗ Wrong - brackets are regex special chars
r'List[str]'

# ✓ Correct - escape brackets
r'List\[str\]'

5. Missing changes_made Entry

python

# ✗ Wrong - silent success, no tracking
content = re.sub(pattern, replacement, content)

# ✓ Correct - track changes
content = re.sub(pattern, replacement, content)
changes_made.append(f"PARAM = {value}")

Debugging Regex Issues

Pattern doesn't match:

Copy actual line from BobConfig.py
Test in regex101.com with Python flavor
Check for extra whitespace or comments
Verify type annotation exact spelling

Match but wrong replacement:

Check capture groups in pattern
Verify f-string uses correct variable
Test with print before writing file

Multiple matches:

Make pattern more specific (add context)
Use parameter name prefix (e.g., VISION_THRESHOLD)
Check for duplicates in BobConfig.py

Quick Reference

Type	Pattern	Example Match
bool	`(True\|False)`	`True`, `False`
int	`\d+`	`42`, `100`
float	`[\d.]+`	`0.5`, `10.0`
str	`"[^"]*"`	`"value"`
Optional[str]	`(?:"[^"]*"\|None)`	`"value"` or `None`
List	`\[.*?\]`	`["a", "b"]`

Pro Tips

Test patterns first - Use regex101.com before coding
Copy exact lines - Use actual BobConfig.py content for testing
Be specific - Include parameter name to avoid false matches
Track changes - Always append to changes_made list
Handle errors - Wrap in try/except
Log changes - Use logger.info for change tracking
Validate input - Check types before regex

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SKILL.md

Regex Configuration Patterns

When to Use

Pattern Structure

Type-Specific Patterns

Boolean Parameters

Integer Parameters

Float Parameters

String Parameters

Optional Parameters

List Parameters

Common Pattern Variations

With Comments

Multiline Parameters

Complete Save Method Template

Testing Regex Patterns

Common Mistakes

1. Wrong Pattern for Float

2. Missing Float Conversion

3. Greedy vs Non-Greedy

4. Not Escaping Special Characters

5. Missing changes_made Entry

Debugging Regex Issues

Quick Reference

Pro Tips