cmd2.history

Classes for storing the history of previously entered commands.

class cmd2.history.History(seq: Iterable[HistoryItem] = ())

A list of HistoryItem objects with additional methods for searching and managing the list.

Cmd instantiates this class into the history attribute, and adds commands to it as a user enters them.

See History for information about the built-in command which allows users to view, search, run, and save previously entered commands.

Developers interested in accessing previously entered commands can use this class to gain access to the historical record.

start_session() None

Start a new session, thereby setting the next index as the first index in the new session.

append(new: HistoryItem) None
append(new: Statement) None

Append a new statement to the end of the History list.

Parameters:

new – Statement object which will be composed into a HistoryItem and added to the end of the list

clear() None

Remove all items from the History list.

get(index: int) HistoryItem

Get item from the History list using 1-based indexing.

Parameters:

index – optional item to get

Returns:

a single HistoryItem

span(span: str, include_persisted: bool = False) OrderedDict[int, HistoryItem]

Return a slice of the History list

Parameters:
  • span – string containing an index or a slice

  • include_persisted – if True, then retrieve full results including from persisted history

Returns:

a dictionary of history items keyed by their 1-based index in ascending order, or an empty dictionary if no results were found

This method can accommodate input in any of these forms:

a..b or a:b a.. or a: ..a or :a -a.. or -a: ..-a or :-a

Different from native python indexing and slicing of arrays, this method uses 1-based array numbering. Users who are not programmers can’t grok zero based numbering. Programmers can sometimes grok zero based numbering. Which reminds me, there are only two hard problems in programming:

  • naming

  • cache invalidation

  • off by one errors

Find history items which contain a given string

Parameters:
  • search – the string to search for

  • include_persisted – if True, then search full history including persisted history

Returns:

a dictionary of history items keyed by their 1-based index in ascending order, or an empty dictionary if the string was not found

Find history items which match a given regular expression

Parameters:
  • regex – the regular expression to search for.

  • include_persisted – if True, then search full history including persisted history

Returns:

a dictionary of history items keyed by their 1-based index in ascending order, or an empty dictionary if the regex was not matched

truncate(max_length: int) None

Truncate the length of the history, dropping the oldest items if necessary

Parameters:

max_length – the maximum length of the history, if negative, all history items will be deleted

Returns:

nothing

to_json() str

Utility method to convert this History into a JSON string for use in persistent history files

static from_json(history_json: str) History

Utility method to restore History from a JSON string

Parameters:

history_json – history data as JSON string (generated using to_json())

Returns:

History object

Raises:
  • json.JSONDecodeError – if passed invalid JSON string

  • KeyError – if JSON is missing required elements

  • ValueError – if history version in JSON isn’t supported

class cmd2.history.HistoryItem(statement: Optional[Statement] = None)

Class used to represent one command in the history list

statement

The Statement object parsed from user input

idx

The 1-based index of this statement in the history list

property raw: str

The raw input from the user for this item.

Proxy property for self.statement.raw

property expanded: str

Return the command as run which includes shortcuts and aliases resolved plus any changes made in hooks

Proxy property for self.statement.expanded_command_line

pr(idx: int, script: bool = False, expanded: bool = False, verbose: bool = False) str

Represent this item in a pretty fashion suitable for printing.

If you pass verbose=True, script and expanded will be ignored

Parameters:
  • idx – The 1-based index of this item in the history list

  • script – True if formatting for a script (No item numbers)

  • expanded – True if expanded command line should be printed

  • verbose – True if expanded and raw should both appear when they are different

Returns:

pretty print string version of a HistoryItem

to_dict() Dict[str, Any]

Utility method to convert this HistoryItem into a dictionary for use in persistent JSON history files

static from_dict(source_dict: Dict[str, Any]) HistoryItem

Utility method to restore a HistoryItem from a dictionary

Parameters:

source_dict – source data dictionary (generated using to_dict())

Returns:

HistoryItem object

Raises:

KeyError – if source_dict is missing required elements