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# cmd2.exceptions

## `` cmd2.exceptions

Custom exceptions for cmd2.

### `` SkipPostcommandHooks

Bases: `Exception`

For when a command has a failed bad enough to skip post command hooks, but not bad enough to print to the user.

### `` Cmd2ArgparseError

Bases: `SkipPostcommandHooks`

A `SkipPostcommandHooks` exception for when a command fails to parse its arguments.

Normally argparse raises a SystemExit exception in these cases. To avoid stopping the command loop, catch the SystemExit and raise this instead. If you still need to run post command hooks after parsing fails, just return instead of raising an exception.

### `` CommandSetRegistrationError

Bases: `Exception`

For when an error occurs while a CommandSet is being added or removed from a cmd2 application.

### `` CompletionError

    CompletionError(*args, apply_style=True)

Bases: `Exception`

Raised during tab completion operations to report any sort of error you want printed.

This can also be used just to display a message, even if it's not an error. For instance, ArgparseCompleter raises CompletionErrors to display tab completion hints and sets apply_style to False so hints aren't colored like error text.

Example use cases:

- Reading a database to retrieve a tab completion data set failed
- A previous command line argument that determines the data set being completed is invalid
- Tab completion hints

Initialize CompletionError instance.

PARAMETER | DESCRIPTION
--- | ---
`apply_style` | If True, then styles.ERROR will be applied to the message text when printed. Set to False in cases where the message text already has the desired style. Defaults to True. TYPE: `bool` DEFAULT: `True`

Source code in `cmd2/exceptions.py`

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    def __init__(self, *args: Any, apply_style: bool = True) -> None:
        """Initialize CompletionError instance.

        :param apply_style: If True, then styles.ERROR will be applied to the message text when printed.
                            Set to False in cases where the message text already has the desired style.
                            Defaults to True.
        """
        self.apply_style = apply_style

        super().__init__(*args)

#### `` apply_style `instance-attribute`

    apply_style = apply_style

### `` PassThroughException

    PassThroughException(*args, wrapped_ex)

Bases: `Exception`

Normally all unhandled exceptions raised during commands get printed to the user.

This class is used to wrap an exception that should be raised instead of printed.

Initialize PassThroughException instance.

PARAMETER | DESCRIPTION
--- | ---
`wrapped_ex` | the exception that will be raised. TYPE: `BaseException`

Source code in `cmd2/exceptions.py`

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    def __init__(self, *args: Any, wrapped_ex: BaseException) -> None:
        """Initialize PassThroughException instance.

        :param wrapped_ex: the exception that will be raised.
        """
        self.wrapped_ex = wrapped_ex
        super().__init__(*args)

#### `` wrapped_ex `instance-attribute`

    wrapped_ex = wrapped_ex

### `` Cmd2ShlexError

Bases: `Exception`

Raised when shlex fails to parse a command line string in StatementParser.

### `` EmbeddedConsoleExit

Bases: `SystemExit`

Custom exception class for use with the py command.

### `` EmptyStatement

Bases: `Exception`

Custom exception class for handling behavior when the user just presses <Enter>.

### `` RedirectionError

Bases: `Exception`

Custom exception class for when redirecting or piping output fails.