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119 lines
3.4 KiB
Org Mode
119 lines
3.4 KiB
Org Mode
:PROPERTIES:
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:ID: 994be8e1-6bf2-4621-adf2-1c9a5ec46521
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:END:
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#+title: Anki: Emacs
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#+date: "2021-05-02 19:18:32 +08:00"
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#+date_modified: "2021-05-06 21:57:59 +08:00"
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#+language: en
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#+property: anki_deck Emacs
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* The overview of buffers
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:PROPERTIES:
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:ANKI_NOTE_TYPE: Styled cards
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:ANKI_NOTE_ID: 1620039512243
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:END:
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** Front
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What is a buffer?
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** Back
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A buffer is anything that Emacs displays.
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It usually display file contents among other examples with ~butterfly~, ~doctor~, or the starting buffer when you first open Emacs.
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While buffers usually have an associated file path, a buffer doesn't need one.
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This is one of the concepts that is applied to other text editors (Vim, Atom, Visual Studio Code).
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* The basics of modes
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:PROPERTIES:
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:ANKI_NOTE_TYPE: Styled cards
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:ANKI_NOTE_ID: 1620039513634
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:END:
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** Front
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What is a mode?
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** Back
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A mode is set of behavior quite similar to Vim modes.
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Emacs further divides modes into two.
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*Major modes are Emacs' way of supporting programming languages and file formats.*
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Programming language support usually comes in major mode — e.g., ~R-mode~ for R files, ~python-mode~ for Python scripts, ~org-mode~ for Org mode documents.
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Think of them as an equivalent to Vim's filetype.
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Only one major mode can be activated in one buffer at a time and all buffers have a major mode.
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*Minor modes usually contain little behavioral changes that improve the editing experience.*
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When enabled, some of them are global modes — affecting every buffer in your session.
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Others are only buffer-local — affecting only the buffer when you activated the mode.
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Unlike major modes, multiple minor modes can be enabled at any given time.
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* Eagle's eye view of a window
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:PROPERTIES:
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:ANKI_DECK: Emacs
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:ANKI_NOTE_TYPE: Styled cards
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:ANKI_NOTE_ID: 1620039514055
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:END:
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** Front
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What is a window?
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** Back
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A window is where the buffers are being displayed.
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One window can display all buffers but only one at a time.
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To display two buffers at a single time, just add another window.
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All windows display the same buffer;
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if the buffer is modified in one of the window, it will show the changes in all windows.
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* Point and marker
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:PROPERTIES:
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:ANKI_NOTE_TYPE: Styled cards
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:ANKI_NOTE_ID: 1620040989788
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:END:
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** Front
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What is a point and a marker?
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** Back
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A point is the current location of the cursor in the buffer.
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You can get the point with ~point~ function.
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Often helpful for interacting with buffers.
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A marker is another point in the buffer.
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It is usually found when interacting with regions when asked for the two points (i.e., the beginning and the ending position).
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Furthermore, a marker can be used to save locations and jump back to that marker when asked.
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* Interacting with buffers in Elisp
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:PROPERTIES:
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:ANKI_NOTE_TYPE: Styled cards
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:ANKI_NOTE_ID: 1620309319576
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:END:
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** Front
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Give a rough example on how to do the following.
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- Create a temporary buffer containing the text "Hello world".
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- Name the buffer and open it as an Org mode document.
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- Get or create the ID for the document.
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** Back
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#+begin_src elisp :exports code
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(with-temp-buffer
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(insert "Hello world")
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(org-mode))
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#+end_src
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* String comparison in Emacs Lisp
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:PROPERTIES:
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:ANKI_NOTE_TYPE: Styled cards
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:ANKI_NOTE_ID: 1620309321231
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:END:
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** Front
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How to compare two strings?
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** Back
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~(string= STR1 STR2)~
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#+begin_src elisp
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(print (string= "WHOA" "whoa"))
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(print (string= "WHOA" (upcase "whoa")))
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(print (string= "Hello world" "HeLL0 World"))
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#+end_src
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#+results:
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:
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: nil
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:
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: t
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:
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: nil
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