Post-transactions

Solver transactions can be extended with the conda_post_transaction_actions plugin hook. This plugin hook accepts a subclass of Action which will be instantiated and appended to the end of conda's transaction action list. When defining the class you must define the following methods:

• execute: this is the primary place to put code you wish to run during the action.

• verify: this is run before the action is executed. This is a good place to check for conditions that would cause the action to fail.

• cleanup: this is run after the action is executed. This is a good place to clean up any resources that were created during the action.

• reverse: in the case of a failure, this allows you to define any reversal procedures.

class CondaPostTransactionAction

Return type to use when defining a post-transaction action hook.

For details on how this is used, see conda_post_transaction_actions().

Parameters:

• name -- Post transaction name (this is just a label)

• action -- Action class which implements plugin behavior. See Action for implementation details

action

name

conda_post_transaction_actions()

Register post-transaction hooks.

Post-transaction hooks run after all other actions run in a UnlinkLinkTransaction. For information about the Action class, see Action.

Example:

from conda import plugins
from conda.core.path_actions import Action


class PrintAction(Action):
    def verify(self):
        print("Performing verification...")
        self._verified = True

    def execute(self):
        print(
            self.transaction_context,
            self.target_prefix,
            self.unlink_precs,
            self.link_precs,
            self.remove_specs,
            self.update_specs,
            self.neutered_specs,
        )

    def reverse(self):
        print("Reversing only happens when `execute` raises an exception.")

    def cleanup(self):
        print("Carrying out cleanup...")


class PrintActionPlugin:
    @plugins.hookimpl
    def conda_post_transaction_actions(
        self,
    ) -> Iterable[plugins.CondaPostTransactionAction]:
        yield plugins.CondaPostTransactionAction(
            name="example-post-transaction-action",
            action=PrintAction,
        )