# Justanesta Claude Code Resources Python Error Handling

> Python Error Handling

- Skill: `tomevault-io/justanesta-claude-code-resources-python-error-handling` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/justanesta-claude-code-resources-python-error-handling`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/justanesta-claude-code-resources-python-error-handling/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/justanesta-claude-code-resources-python-error-handling

---


# Python Error Handling

Modern error handling, logging, and debugging patterns.

## Core Principles

1. **Specific exceptions** - Catch specific types, not `Exception`
2. **Fail fast** - Raise errors early at source
3. **Context in errors** - Include relevant information
4. **Log, don't just print** - Structured, searchable logs

## Exception Handling Patterns

**Be specific about what you catch**

```python
# BAD - Too broad
try:
    result = process_data()
except:
    print("Error occurred")

# GOOD - Specific handling
try:
    result = process_data()
except FileNotFoundError as e:
    logger.error(f"Config file not found: {e}")
    use_defaults()
except ValueError as e:
    logger.error(f"Invalid data: {e}")
    raise
except Exception as e:
    logger.error(f"Unexpected error: {e}", exc_info=True)
    raise
```

See [exception-patterns.md](references/exception-patterns.md).

## Custom Exceptions

**Create domain-specific exceptions**

```python
class DataValidationError(ValueError):
    """Raised when data validation fails."""
    pass

class APIError(Exception):
    """Base exception for API errors."""
    def __init__(self, message: str, status_code: int):
        self.message = message
        self.status_code = status_code
        super().__init__(self.message)

class APITimeout(APIError):
    """API request timeout."""
    def __init__(self, message: str):
        super().__init__(message, status_code=504)
```

See [custom-exceptions.md](references/custom-exceptions.md).

## Context Managers for Cleanup

```python
from contextlib import contextmanager

@contextmanager
def managed_resource(name):
    resource = acquire_resource(name)
    try:
        yield resource
    finally:
        release_resource(resource)  # Always called

with managed_resource("database") as db:
    db.query("SELECT * FROM users")
    # Even if exception, resource released
```

## Logging with Structlog

```python
import structlog

logger = structlog.get_logger()

def process_order(order_id: str):
    log = logger.bind(order_id=order_id)
    
    try:
        log.info("processing_order_started")
        result = process(order_id)
        log.info("processing_order_completed", result=result)
        return result
    except Exception as e:
        log.error("processing_order_failed", error=str(e))
        raise
```

See [logging-patterns.md](references/logging-patterns.md).

## Debugging Tools

**Use pdb for interactive debugging**

```python
def complex_function(data):
    # Set breakpoint
    import pdb; pdb.set_trace()
    
    # Or in Python 3.7+
    breakpoint()
    
    result = process(data)
    return result
```

See [debugging-tools.md](references/debugging-tools.md).

## Error Recovery Patterns

```python
from tenacity import retry, stop_after_attempt, wait_exponential

@retry(
    stop=stop_after_attempt(3),
    wait=wait_exponential(multiplier=1, min=4, max=10)
)
def unreliable_api_call():
    """Retry with exponential backoff."""
    response = requests.get("https://api.example.com")
    response.raise_for_status()
    return response.json()
```

See [retry-patterns.md](references/retry-patterns.md).

source: Python error handling best practices

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