designing-python-apis

# Python API Design

## Core Principles

1. **Simplicity**: Simple things simple, complex things possible
2. **Consistency**: Similar operations work similarly
3. **Least Surprise**: Behave as users expect
4. **Discoverability**: Find via autocomplete and help

## Progressive Disclosure Pattern

```python
# Level 1: Simple functions
from mylib import encode, decode
result = encode(37.7749, -122.4194)

# Level 2: Configurable classes
from mylib import Encoder
encoder = Encoder(precision=15)

# Level 3: Low-level access
from mylib.internals import BitEncoder
```

## Naming Conventions

```python
# Actions: verbs
encode(), decode(), validate()

# Retrieval: get_*
get_user(), get_config()

# Boolean: is_*, has_*, can_*
is_valid(), has_permission()

# Conversion: to_*, from_*
to_dict(), from_json()
```

## Error Handling

```python
class MyLibError(Exception):
    """Base exception with helpful messages."""
    def __init__(self, message: str, *, hint: str = None):
        super().__init__(message)
        self.hint = hint

# Usage
raise ValidationError(
    f"Latitude must be -90 to 90, got {lat}",
    hint="Did you swap latitude and longitude?"
)
```

## Deprecation

```python
import warnings

def old_function():
    warnings.warn(
        "old_function() deprecated, use new_function()",
        DeprecationWarning,
        stacklevel=2,
    )
    return new_function()
```

## Anti-Patterns

```python
# Bad: Boolean trap
process(data, True, False, True)

# Good: Keyword arguments
process(data, validate=True, cache=False)

# Bad: Mutable default
def process(items: list = []):

# Good: None default
def process(items: list | None = None):
```

For detailed patterns, see:
- **[PATTERNS.md](PATTERNS.md)** - Builder, factory, and advanced patterns
- **[EVOLUTION.md](EVOLUTION.md)** - API versioning and migration guides

## Review Checklist

```
Naming:
- [ ] Clear, self-documenting names
- [ ] Consistent patterns throughout
- [ ] Boolean params read naturally

Parameters:
- [