---
title: BasePassManager (v1.3)
description: API reference for qiskit.passmanager.BasePassManager in qiskit v1.3
source: https://eu-de.quantum.cloud.ibm.com/docs/en/api/qiskit/1.3/qiskit.passmanager.BasePassManager
---

# BasePassManager

*class* `qiskit.passmanager.BasePassManager(tasks=(), max_iteration=1000)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.3/qiskit/passmanager/passmanager.py#L33-L267)

Bases: [`ABC`](https://docs.python.org/3/library/abc.html#abc.ABC)

Pass manager base class.

Initialize an empty pass manager object.

**Parameters**

- **tasks** (*Task |* [*list*](https://docs.python.org/3/library/stdtypes.html#list)*\[Task]*) – A pass set to be added to the pass manager schedule.
- **max\_iteration** ([*int*](https://docs.python.org/3/library/functions.html#int)) – The maximum number of iterations the schedule will be looped if the condition is not met.

## Methods

### append

`append(tasks)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.3/qiskit/passmanager/passmanager.py#L57-L74)

Append tasks to the schedule of passes.

**Parameters**

**tasks** (*Task |* [*list*](https://docs.python.org/3/library/stdtypes.html#list)*\[Task]*) – A set of pass manager tasks to be added to schedule.

**Raises**

[**TypeError**](https://docs.python.org/3/library/exceptions.html#TypeError) – When any element of tasks is not a subclass of passmanager Task.

**Return type**

None

### remove

`remove(index)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.3/qiskit/passmanager/passmanager.py#L96-L108)

Removes a particular pass in the scheduler.

**Parameters**

**index** ([*int*](https://docs.python.org/3/library/functions.html#int)) – Pass index to remove, based on the position in `passes()`.

**Raises**

[**PassManagerError**](/docs/api/qiskit/1.3/passmanager#qiskit.passmanager.PassManagerError "qiskit.passmanager.PassManagerError") – If the index is not found.

**Return type**

None

### replace

`replace(index, tasks)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.3/qiskit/passmanager/passmanager.py#L76-L94)

Replace a particular pass in the scheduler.

**Parameters**

- **index** ([*int*](https://docs.python.org/3/library/functions.html#int)) – Task index to replace, based on the position in `tasks()`
- **tasks** (*Task |* [*list*](https://docs.python.org/3/library/stdtypes.html#list)*\[Task]*) – A set of pass manager tasks to be added to schedule.

**Raises**

- [**TypeError**](https://docs.python.org/3/library/exceptions.html#TypeError) – When any element of tasks is not a subclass of passmanager Task.
- [**PassManagerError**](/docs/api/qiskit/1.3/passmanager#qiskit.passmanager.PassManagerError "qiskit.passmanager.PassManagerError") – If the index is not found.

**Return type**

None

### run

`run(in_programs, callback=None, num_processes=None, **kwargs)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.3/qiskit/passmanager/passmanager.py#L172-L251)

Run all the passes on the specified `in_programs`.

**Parameters**

- **in\_programs** (*Any |* [*list*](https://docs.python.org/3/library/stdtypes.html#list)*\[Any]*) – Input programs to transform via all the registered passes. A single input object cannot be a Python builtin list object. A list object is considered as multiple input objects to optimize.

- **callback** (*Callable*) –

  A callback function that will be called after each pass execution. The function will be called with 4 keyword arguments:

  ```python
  task (GenericPass): the pass being run
  passmanager_ir (Any): depending on pass manager subclass
  property_set (PropertySet): the property set
  running_time (float): the time to execute the pass
  count (int): the index for the pass execution
  ```

  The exact arguments pass expose the internals of the pass manager and are subject to change as the pass manager internals change. If you intend to reuse a callback function over multiple releases be sure to check that the arguments being passed are the same.

  To use the callback feature you define a function that will take in kwargs dict and access the variables. For example:

  ```python
  def callback_func(**kwargs):
      task = kwargs['task']
      passmanager_ir = kwargs['passmanager_ir']
      property_set = kwargs['property_set']
      running_time = kwargs['running_time']
      count = kwargs['count']
      ...
  ```

- **num\_processes** ([*int*](https://docs.python.org/3/library/functions.html#int)) – The maximum number of parallel processes to launch if parallel execution is enabled. This argument overrides `num_processes` in the user configuration file, and the `QISKIT_NUM_PROCS` environment variable. If set to `None` the system default or local user configuration will be used.

- **kwargs** – Arbitrary arguments passed to the compiler frontend and backend.

**Returns**

The transformed program(s).

**Return type**

Any

### to\_flow\_controller

`to_flow_controller()`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.3/qiskit/passmanager/passmanager.py#L253-L261)

Linearize this manager into a single [`FlowControllerLinear`](/docs/api/qiskit/1.3/qiskit.passmanager.FlowControllerLinear "qiskit.passmanager.FlowControllerLinear"), so that it can be nested inside another pass manager.

**Returns**

A linearized pass manager.

**Return type**

[*FlowControllerLinear*](/docs/api/qiskit/1.3/qiskit.passmanager.FlowControllerLinear "qiskit.passmanager.flow_controllers.FlowControllerLinear")