Method has_identifier

qiskit/circuit/quantumcircuit.py:3286–3313

Check whether an identifier is accessible in this scope. Args: name_or_ident: the instance, or name of the identifier to check. If this is a :class:`.expr.Var` or :class:`.expr.Stretch` node, the matched instance must be exactly the given one for

(self, name_or_ident: str | expr.Var | expr.Stretch, /)

        return default

    def has_identifier(self, name_or_ident: str | expr.Var | expr.Stretch, /) -> bool:
        """Check whether an identifier is accessible in this scope.

        Args:
            name_or_ident: the instance, or name of the identifier to check.  If this is a
                :class:`.expr.Var` or :class:`.expr.Stretch` node, the matched instance must
                be exactly the given one for this function to return ``True``.

        Returns:
            whether a matching identifier is accessible.

        See also:
            :meth:`QuantumCircuit.get_identifier`
                Retrieve the :class:`.expr.Var` or :class:`.expr.Stretch` instance from this
                circuit by name.
            :meth:`QuantumCircuit.has_var`
                The same as this method, but ignoring anything that isn't a
                run-time :class:`expr.Var` variable.
            :meth:`QuantumCircuit.has_stretch`
                The same as this method, but ignoring anything that isn't a
                run-time :class:`expr.Stretch` variable.
            :meth:`QuantumCircuit.has_parameter`
                A similar method to this, but for compile-time :class:`.Parameter`\\ s instead of
                run-time :class:`.expr.Var` variables.
        """
        if isinstance(name_or_ident, str):
            return self.get_identifier(name_or_ident, None) is not None
        return self.get_identifier(name_or_ident.name, None) == name_or_ident

    def _prepare_new_var(
        self, name_or_var: str | expr.Var, type_: types.Type | None, /