Package basic-mode provides a major mode for editing BASIC code in GNU Emacs. Features include syntax highlighting and indentation, as well as support for auto-numbering and renumering of code lines.
The recommended way to install basic-mode is from MELPA.
To install manually, place basic-mode.el in your load-path, and add the following lines of code to your init file:
(autoload 'basic-mode "basic-mode" "Major mode for editing BASIC code." t)
(add-to-list 'auto-mode-alist '("\\.bas\\'" . basic-mode))TAB indents the current line of BASIC code, including line numbers if available. If the region is active, TAB indents all lines in the region.
C-c C-f formats the entire buffer; indents all lines, and removes any extra whitespace. If the region is active, C-c C-f formats all lines in the region.
For classic BASIC, basic-mode provides several functions to manage line numbers. Customize variables basic-auto-number and basic-line-number-cols to your liking to turn on line numbers.
With line numbers turned on, RET will start new lines with a fresh line number. The line number increment is defined by variable basic-auto-number. C-c C-r will renumber all lines in the entire buffer, including any jumps in the code. The line number increment used when renumbering is defined by variable basic-renumber-increment. If the region is active, C-c C-r renumbers all lines in the region instead.
With line numbers turned on, C-c C-f will also respect line numbers, and the value configured in basic-line-number-cols while formatting.
Package basic-mode also provides additional functionality to navigate in the source code. M-. will find and move to the line number, label, or variable at point, and M-, will move back again. For more information, see function xref-find-definitions.
The following table lists the customizable variables that affect basic-mode in some way:
| Name | Description | Default Value |
|---|---|---|
| basic-auto-number | If non-nil, auto-number new lines by incrementing the line number with this value. | nil |
| basic-delete-trailing-whitespace | If non-nil, basic-format-code deletes trailing whitespace while formatting. | t |
| basic-indent-offset | The number of columns to indent code blocks, for example inside an IF statement. | 4 |
| basic-line-number-cols | The number of columns allocated to line numbers at the beginning of the line. | 0 |
| basic-mode-hook | Hook run when entering BASIC mode. | nil |
| basic-renumber-increment | Default line number increment when renumbering lines. | 10 |
| basic-renumber-unnumbered-lines | If non-nil, lines without line numbers are also renumbered when renumbering lines. | t |
| basic-syntax-highlighting-require-separator | If non-nil, only keywords separated by separators will be highlighted. If nil, keywords separated by numbers will also be highlighted. | t |
| delete-trailing-lines (simple.el) | If non-nil, basic-format-code deletes trailing empty lines while formatting. | t |