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| emacs_tutorial [2021/03/21 06:11] – [Search & Replace] hc9 | emacs_tutorial [2021/03/21 06:18] – [Emacs Modes] hc9 |
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| ===== Emacs Modes ===== | ===== Emacs Modes ===== |
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| Emacs buffers are associated with one so-called //major mode// and one or more //minor modes//. Major modes typically denote a type of file, and are associated with special command sequences and syntax highlighting just for that file type. Minor modes change the behavior of an associated major mode in small ways. For example, the major mode for editing text is called text-mode, while the one for editing HTML is called html-mode. Both text and html modes have a minor mode called refill-mode that automatically formats paragraphs of text as you type (similar to the behavior you expect from a word processor). You can switch modes by just typing "M-x modename", so "M-x html-mode" would switch you into html-mode. Emacs can usually figure out the mode to use by the file extension, so if you visit (load with "C-x C-f") a file ending in .html or .htm, html-mode will be selected for you, and if you visit a file ending in .txt, text mode will be selected. | Emacs buffers are associated with one so-called //major mode// and one or more //minor modes//. Major modes typically denote a type of file, and are associated with special command sequences and syntax highlighting just for that file type. Minor modes change the behavior of an associated major mode in small ways. For example, the major mode for editing text is called text-mode, while the one for editing HTML is called html-mode. Both text and html modes have a minor mode called refill-mode that automatically formats paragraphs of text as you type (similar to the behavior you expect from a word processor). You can switch modes by just typing ''M-x modename'', so ''M-x html-mode'' would switch you into html-mode. Emacs can usually figure out the mode to use by the file extension, so if you visit (load with ''C-x C-f'') a file ending in .html or .htm, html-mode will be selected for you, and if you visit a file ending in .txt, text mode will be selected. |
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| As an example, say you want to create a new text document. You type "C-x C-f foo.txt" and Emacs creates an empty buffer for you named "foo.txt". Notice the modeline displays "(Text)" to indicate the major mode. Now type "M-x refi" and hit the Tab key. Emacs will complete "refill-mode". Hit enter, now the modeline displays "(Text Refill)" to indicate the major and minor modes in effect. Experiment with refill mode by typing some text and watch as Emacs wraps the lines for you. Now go back and add or delete some text and notice how the paragraph re-formats itself. Modes toggle on and off, so a second "M-x refill-mode" will turn refilling off. Type some text and notice Emacs no longer wraps lines or formats paragraphs for you. The mode for buffers not associated with any special file type is called fundamental-mode. This is the mode your scratch buffer is put in at startup. | As an example, say you want to create a new text document. You type ''C-x C-f foo.txt'' and Emacs creates an empty buffer for you named "foo.txt". Notice the modeline displays "(Text)" to indicate the major mode. Now type ''M-x refi'' and hit the Tab key. Emacs will complete "refill-mode". Hit enter, now the modeline displays "(Text Refill)" to indicate the major and minor modes in effect. Experiment with refill mode by typing some text and watch as Emacs wraps the lines for you. Now go back and add or delete some text and notice how the paragraph re-formats itself. Modes toggle on and off, so a second ''M-x refill-mode'' will turn refilling off. Type some text and notice Emacs no longer wraps lines or formats paragraphs for you. The mode for buffers not associated with any special file type is called fundamental-mode. This is the mode your scratch buffer is put in at startup. |
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| There are lots of Emacs major modes, many of which are useful for programmers. There is c-mode, perl-mode, and c++-mode, for example. Each mode has its own key bindings and syntax highlighting rules. You can see the details of the currently selected major mode by typing "C-h m". To enable syntax highlighting on a source-code file, you can type "M-x global-font-lock-mode" (on some operating systems, packaged versions of Emacs will enable font lock [syntax highlighting] for you automatically). | There are lots of Emacs major modes, many of which are useful for programmers. There is c-mode, perl-mode, and c++-mode, for example. Each mode has its own key bindings and syntax highlighting rules. You can see the details of the currently selected major mode by typing ''C-h m''. To enable syntax highlighting on a source-code file, you can type ''M-x global-font-lock-mode'' (on some operating systems, packaged versions of Emacs will enable font lock [syntax highlighting] for you automatically). |
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| As an example of special key bindings, in html-mode, the key sequence "C-c C-c h" will insert a properly formatted hyperlink into the text, prompting you for the URL first. In other modes this key sequence will have no effect. | As an example of special key bindings, in html-mode, the key sequence ''C-c C-c h'' will insert a properly formatted hyperlink into the text, prompting you for the URL first. In other modes this key sequence will have no effect. |
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| Here are some of the most useful mode commands: | Here are some of the most useful mode commands: |
