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"""
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===============================================
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Top-level exceptions (:mod:`qiskit.exceptions`)
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===============================================
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All Qiskit-related errors raised by Qiskit are subclasses of the base:
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.. autoexception:: QiskitError
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.. note::
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Errors that are just general programming errors, such as incorrect typing, may still raise
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standard Python errors such as ``TypeError``. :exc:`QiskitError` is generally for errors raised
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in usage that is particular to Qiskit.
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Many of the Qiskit subpackages define their own more granular error, to help in catching only the
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subset of errors you care about. For example, :mod:`qiskit.circuit` almost exclusively uses
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:exc:`.CircuitError`, while both :exc:`.QASM2ExportError` and :exc:`.QASM2ParseError` derive from
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:exc:`.QASM2Error` in :mod:`qiskit.qasm2`, which is in turn a type of :exc:`.QiskitError`.
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Qiskit has several optional features that depend on other packages that are not required for a
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minimal install. You can read more about those, and ways to check for their presence, in
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:mod:`qiskit.utils.optionals`. Trying to use a feature that requires an optional extra will raise a
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particular error, which subclasses both :exc:`QiskitError` and the Python built-in ``ImportError``.
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.. autoexception:: MissingOptionalLibraryError
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Two more uncommon errors relate to failures in reading user-configuration files, or specifying a
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filename that cannot be used:
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.. autoexception:: QiskitUserConfigError
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.. autoexception:: InvalidFileError
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"""
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from typing import Optional
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class QiskitError(Exception):
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"""Base class for errors raised by Qiskit."""
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def __init__(self, *message):
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"""Set the error message."""
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super().__init__(" ".join(message))
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self.message = " ".join(message)
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def __str__(self):
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"""Return the message."""
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return repr(self.message)
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class QiskitUserConfigError(QiskitError):
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"""Raised when an error is encountered reading a user config file."""
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message = "User config invalid"
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class MissingOptionalLibraryError(QiskitError, ImportError):
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"""Raised when an optional library is missing."""
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def __init__(
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self, libname: str, name: str, pip_install: Optional[str] = None, msg: Optional[str] = None
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) -> None:
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"""Set the error message.
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Args:
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libname: Name of missing library
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name: Name of class, function, module that uses this library
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pip_install: pip install command, if any
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msg: Descriptive message, if any
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"""
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message = [f"The '{libname}' library is required to use '{name}'."]
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if pip_install:
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message.append(f"You can install it with '{pip_install}'.")
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if msg:
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message.append(f" {msg}.")
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super().__init__(" ".join(message))
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self.message = " ".join(message)
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def __str__(self) -> str:
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"""Return the message."""
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return repr(self.message)
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class InvalidFileError(QiskitError):
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"""Raised when the file provided is not valid for the specific task."""
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