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22.2.7 Tabulated List mode

Tabulated List mode is a major mode for displaying tabulated data, i.e., data consisting of entries, each entry occupying one row of text with its contents divided into columns. Tabulated List mode provides facilities for pretty-printing rows and columns, and sorting the rows according to the values in each column. It is derived from Special mode (see Basic Major Modes).

Tabulated List mode is intended to be used as a parent mode by a more specialized major mode. Examples include Process Menu mode (see Process Information) and Package Menu mode (see Package Menu).

Such a derived mode should use define-derived-mode in the usual way, specifying tabulated-list-mode as the second argument (see Derived Modes). The body of the define-derived-mode form should specify the format of the tabulated data, by assigning values to the variables documented below; optionally, it can then call the function tabulated-list-init-header, which will populate a header with the names of the columns.

The derived mode should also define a listing command. This, not the mode command, is what the user calls (e.g., M-x list-processes). The listing command should create or switch to a buffer, turn on the derived mode, specify the tabulated data, and finally call tabulated-list-print to populate the buffer.

— Variable: tabulated-list-format

This buffer-local variable specifies the format of the Tabulated List data. Its value should be a vector. Each element of the vector represents a data column, and should be a list (name width sort), where

— Variable: tabulated-list-entries

This buffer-local variable specifies the entries displayed in the Tabulated List buffer. Its value should be either a list, or a function.

If the value is a list, each list element corresponds to one entry, and should have the form (id contents), where

Otherwise, the value should be a function which returns a list of the above form when called with no arguments.

— Variable: tabulated-list-revert-hook

This normal hook is run prior to reverting a Tabulated List buffer. A derived mode can add a function to this hook to recompute tabulated-list-entries.

— Variable: tabulated-list-printer

The value of this variable is the function called to insert an entry at point, including its terminating newline. The function should accept two arguments, id and contents, having the same meanings as in tabulated-list-entries. The default value is a function which inserts an entry in a straightforward way; a mode which uses Tabulated List mode in a more complex way can specify another function.

— Variable: tabulated-list-sort-key

The value of this variable specifies the current sort key for the Tabulated List buffer. If it is nil, no sorting is done. Otherwise, it should have the form (name . flip), where name is a string matching one of the column names in tabulated-list-format, and flip, if non-nil, means to invert the sort order.

— Function: tabulated-list-init-header

This function computes and sets header-line-format for the Tabulated List buffer (see Header Lines), and assigns a keymap to the header line to allow sorting entries by clicking on column headers.

Modes derived from Tabulated List mode should call this after setting the above variables (in particular, only after setting tabulated-list-format).

— Function: tabulated-list-print &optional remember-pos update

This function populates the current buffer with entries. It should be called by the listing command. It erases the buffer, sorts the entries specified by tabulated-list-entries according to tabulated-list-sort-key, then calls the function specified by tabulated-list-printer to insert each entry.

If the optional argument remember-pos is non-nil, this function looks for the id element on the current line, if any, and tries to move to that entry after all the entries are (re)inserted.

If the optional argument update is non-nil, this function will only erase or add entries that have changed since the last print. This is several times faster if most entries haven't changed since the last time this function was called. The only difference in outcome is that tags placed via tabulated-list-put-tag will not be removed from entries that haven't changed (normally all tags are removed).