Function naming logic

This vignette describes the logic behind the names of the {dm}-functions.

In general, the functions are implemented in such a way that no function can handle instances of both dm classes (dm and dm_zoomed) as an argument. In most situations, a dm_zoomed behaves like a table and there are mostly no explicit functions available for this class, but rather methods (see vignette “Zooming and manipulating tables”.


  1. dm_: There are two cases for this prefix:
    • The function takes a dm object as a first argument
    • The function constructs a dm object from other objects
  2. check_: Certain tests on the arguments are performed and an error is thrown in case they are not passed. If the tests are passed, the first argument is returned invisibly.
  3. examine_: The function executes checks and returns an object containing an overview of the results of the checks.

Most important extended prefixes dm_..._:

  1. dm_examine_: The function examines several aspects of a dm object
  2. dm_add_: Adds either key constraints or new tables to a dm
  3. dm_get_: Retrieves a specific piece of information about the dm (often a part of its constituents)
  4. dm_rm_: Removes either key constraints or tables from a dm


  1. _dm: Validators, checkers, or coercers
  2. _to_tbl: Data from a dm is processed in a way that a tibble is produced
  3. _candidates: If key-candidates are to be calculated and presented in tibble-form
  4. _pk(s): Relates to primary key(s)
  5. _fk(s): Relates to foreign key(s)
  6. _tbl: Add/remove/select/rename a tibble to/from/within a dm object
  7. _colors: Relates to the colors for the visualization of a dm object
  8. _zoomed: Insert, update, or discard the zoomed table. In combination with the prefix dm_, this indicates that the first argument is a dm_zoomed rather than a dm.