Error Handling

class HydraException(Exception):
    """Base exception for all Hydra-specific errors."""

class CompactHydraException(HydraException):
    """Base for exceptions that should display compactly."""

class MissingConfigException(IOError, ConfigCompositionException):
    """Raised when a required configuration cannot be found."""
    
    def __init__(
        self,
        message: str,
        missing_cfg_file: Optional[str] = None,
        options: Optional[Sequence[str]] = None
    ) -> None:
        """
        Parameters:
        - message: Error description
        - missing_cfg_file: Name of missing config file
        - options: Available config options
        """

class ConfigCompositionException(CompactHydraException):
    """Raised when configuration composition fails."""

class SearchPathException(CompactHydraException):
    """Raised when config search path operations fail."""

class OverrideParseException(CompactHydraException):
    """Raised when command-line override parsing fails."""
    
    def __init__(self, override: str, message: str) -> None:
        """
        Parameters:
        - override: The problematic override string
        - message: Error description
        """
        super().__init__(message)
        self.override = override
        self.message = message

class InstantiationException(CompactHydraException):
    """Raised when object instantiation fails."""

class HydraDeprecationError(HydraException):
    """Raised when deprecated functionality is used inappropriately."""

from hydra import compose, initialize
from hydra.errors import MissingConfigException, ConfigCompositionException

try:
    with initialize(version_base=None, config_path="conf"):
        cfg = compose(config_name="nonexistent_config")
except MissingConfigException as e:
    print(f"Config not found: {e}")
    if e.missing_cfg_file:
        print(f"Missing file: {e.missing_cfg_file}")
    if e.options:
        print(f"Available options: {e.options}")

# Handle general composition errors
try:
    with initialize(version_base=None, config_path="conf"):
        cfg = compose(config_name="config", overrides=["invalid_override"])
except ConfigCompositionException as e:
    print(f"Composition failed: {e}")

from hydra.errors import OverrideParseException
from hydra._internal.core_plugins.basic_sweeper import BasicSweeper

# Simulate override parsing error
try:
    # This would typically happen internally during command-line parsing
    problematic_override = "key=value=extra_equals"
    raise OverrideParseException(
        override=problematic_override,
        message="Too many equals signs in override"
    )
except OverrideParseException as e:
    print(f"Override parsing failed: {e.message}")
    print(f"Problematic override: {e.override}")

from hydra.utils import instantiate
from hydra.errors import InstantiationException
from omegaconf import DictConfig

# Handle instantiation failures
config = DictConfig({
    "_target_": "nonexistent.module.Class",
    "param": "value"
})

try:
    obj = instantiate(config)
except InstantiationException as e:
    print(f"Instantiation failed: {e}")
    # Could implement fallback logic here
    fallback_config = DictConfig({
        "_target_": "builtins.dict",
        "param": "value"
    })
    obj = instantiate(fallback_config)

from hydra import initialize_config_dir
from hydra.errors import SearchPathException, HydraException

try:
    # Invalid config directory
    with initialize_config_dir(
        version_base=None, 
        config_dir="/nonexistent/directory"
    ):
        pass
except HydraException as e:
    # This might be SearchPathException or another type
    print(f"Hydra error: {e}")
    if isinstance(e, SearchPathException):
        print("Search path specific error")

from hydra.errors import HydraDeprecationError
from hydra.types import TargetConf

try:
    # This will raise HydraDeprecationError in newer versions
    target = TargetConf(_target_="my.module.Class")
except HydraDeprecationError as e:
    print(f"Deprecated functionality: {e}")
    # Use modern approach instead
    from omegaconf import DictConfig
    config = DictConfig({"_target_": "my.module.Class"})

from hydra import main, compose, initialize
from hydra.errors import (
    HydraException,
    MissingConfigException,
    ConfigCompositionException,
    InstantiationException,
    OverrideParseException
)
from omegaconf import DictConfig

def safe_config_composition(config_path: str, config_name: str, overrides: list = None):
    """Safely compose configuration with comprehensive error handling."""
    
    if overrides is None:
        overrides = []
        
    try:
        with initialize(version_base=None, config_path=config_path):
            cfg = compose(config_name=config_name, overrides=overrides)
            return cfg
    except MissingConfigException as e:
        print(f"Configuration not found: {e}")
        if e.options:
            print(f"Available configurations: {', '.join(e.options)}")
        return None
    except ConfigCompositionException as e:
        print(f"Failed to compose configuration: {e}")
        return None
    except OverrideParseException as e:
        print(f"Invalid override '{e.override}': {e.message}")
        return None
    except HydraException as e:
        print(f"Hydra error: {e}")
        return None
    except Exception as e:
        print(f"Unexpected error: {e}")
        return None

# Usage
cfg = safe_config_composition("conf", "config", ["db.port=5432"])
if cfg is not None:
    print("Configuration loaded successfully")

import logging
from hydra.errors import HydraException
from hydra import main
from omegaconf import DictConfig

# Set up logging to capture Hydra errors
logging.basicConfig(level=logging.DEBUG)
logger = logging.getLogger(__name__)

@main(version_base=None, config_path="conf", config_name="config")
def my_app(cfg: DictConfig) -> None:
    try:
        # Application logic that might fail
        risky_operation(cfg)
    except HydraException as e:
        logger.error(f"Hydra-specific error: {e}", exc_info=True)
        # Could implement retry logic or graceful degradation
    except Exception as e:
        logger.error(f"Unexpected error: {e}", exc_info=True)
        raise

def risky_operation(cfg: DictConfig):
    """Simulate operation that might cause Hydra errors."""
    from hydra.utils import instantiate
    
    if "_target_" in cfg:
        return instantiate(cfg)
    else:
        raise ValueError("No _target_ specified")

from hydra.errors import HydraException

class AppConfigurationError(HydraException):
    """Application-specific configuration error."""
    
    def __init__(self, message: str, config_section: str = None):
        super().__init__(message)
        self.config_section = config_section

def validate_config(cfg: DictConfig):
    """Validate configuration and raise custom errors."""
    
    if not cfg.get("database"):
        raise AppConfigurationError(
            "Database configuration is required",
            config_section="database"
        )
    
    if cfg.database.port < 1 or cfg.database.port > 65535:
        raise AppConfigurationError(
            f"Invalid database port: {cfg.database.port}",
            config_section="database.port"
        )

# Usage with custom error handling
try:
    validate_config(cfg)
except AppConfigurationError as e:
    print(f"Configuration validation failed: {e}")
    if e.config_section:
        print(f"Problem in section: {e.config_section}")
except HydraException as e:
    print(f"Hydra error: {e}")

from hydra.errors import MissingConfigException, InstantiationException
from hydra import initialize, compose
from hydra.utils import instantiate

def robust_app_initialization():
    """Initialize app with fallback configurations."""
    
    configs_to_try = ["prod", "dev", "default"]
    
    for config_name in configs_to_try:
        try:
            with initialize(version_base=None, config_path="conf"):
                cfg = compose(config_name=config_name)
                return cfg
        except MissingConfigException:
            continue
    
    # Last resort: create minimal config
    from omegaconf import DictConfig
    return DictConfig({"app": {"name": "fallback"}})

def robust_instantiation(config, fallback_target=None):
    """Instantiate with fallback on failure."""
    
    try:
        return instantiate(config)
    except InstantiationException as e:
        print(f"Primary instantiation failed: {e}")
        
        if fallback_target:
            try:
                fallback_config = {"_target_": fallback_target}
                return instantiate(fallback_config)
            except InstantiationException:
                print("Fallback instantiation also failed")
        
        return None