| Developer(s) | Edward K. Ream, et al. |
|---|---|
| Stable release | 6.7.4 [1] / 17 August 2023 |
| Repository | |
| Written in | Python |
| Operating system | Cross-platform |
| Size | ~9 MB |
| Type | Text editor, Outliner, IDE |
| License | MIT |
| Website | leo-editor |
Leo is an open-source text editor/outliner that features clones (virtual copies of outline nodes) as a central tool of organization, navigation, customization and scripting.
Leo can manipulate text or code in any human or computer programming language (e.g., Python, C, C++, Java), as Leo is a language-independent or "adaptable LPE" (literate programming environment). [2] Syntax highlighting is provided for many different programming languages. [3] Leo is written in Python and can be extended with plugins written in Python. The GUI uses the Qt toolkit; the syntax-aware editor is based on Scintilla. Leo outlines are stored as XML files.
Leo's foremost functionality, in addition to text editing, is that of an outliner, with a "vast range of convenience features for structuring and managing outlines" both by drag-and-drop via GUI and by keyboard commands. [3] Leo's outline pane shows a tree of data nodes. Nodes contain headlines, body text, and other information. Headlines naturally serve as descriptions of the body text. For example, @file nodes are nodes whose headline starts with @file. Leo trees are in fact directed acyclic graphs; nodes may have more than one parent. Leo calls such nodes clones. Clones appear in several places in the outline pane. Views are simply nodes whose children contain clones. A single outline may contain arbitrarily many views of the nodes contained therein.
@file nodes represent external files, files on the computer's file system other than the outline file. When saving an outline Leo automatically writes all changed @file trees back to the external files. Comments, called sentinel lines, in external files represent the outline structure. When Leo reads an outline, these comments allow Leo to recreate @file trees using only the data in the external file. @auto nodes and @clean nodes represent external files without using sentinel comments. When reading @auto nodes, Leo uses the program structure of the external file to create the @auto tree. When reading @clean nodes, Leo uses the structure of the outline to create the @clean tree.
Leo's outline or hierarchical structure is distinct from the web of interleaved program and documentation "chunks" associated with classic literate programming tools. [4] [5] The body text of any Leo node may contain a Leo script, a Python script executed in the context of a Leo outline. A simple API gives Leo scripts full access to all data in loaded outlines, as well as full access to Leo's own source code. The API includes Python iterators that allow scripts to traverse outlines easily. Scripts may be composed of any tree of nodes. A markup language similar to noweb tells Leo how to create scripts from (parts of) an outline. Headlines control and guide scripts. For example, @button nodes create user-defined commands. Leo executes the script of an @button node in the context of any other outline node.
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Graphviz is a package of open-source tools initiated by AT&T Labs Research for drawing graphs specified in DOT language scripts having the file name extension "gv". It also provides libraries for software applications to use the tools. Graphviz is free software licensed under the Eclipse Public License.
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This article provides basic comparisons for notable text editors. More feature details for text editors are available from the Category of text editor features and from the individual products' articles. This article may not be up-to-date or necessarily all-inclusive.
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Org Mode is a mode for document editing, formatting, and organizing within the free software text editor GNU Emacs and its derivatives, designed for notes, planning, and authoring. The name is used to encompass plain text files that include simple marks to indicate levels of a hierarchy, and an editor with functions that can read the markup and manipulate hierarchy elements.
Sublime Text is a shareware text and source code editor available for Windows, macOS, and Linux. It natively supports many programming languages and markup languages. Users can customize it with themes and expand its functionality with plugins, typically community-built and maintained under free-software licenses. To facilitate plugins, Sublime Text features a Python API. The editor utilizes minimal interface and contains features for programmers including configurable syntax highlighting, code folding, search-and-replace supporting regular-expressions, terminal output window, and more. It is proprietary software, but a free evaluation version is available.
Spyder is an open-source cross-platform integrated development environment (IDE) for scientific programming in the Python language. Spyder integrates with a number of prominent packages in the scientific Python stack, including NumPy, SciPy, Matplotlib, pandas, IPython, SymPy and Cython, as well as other open-source software. It is released under the MIT license.
Atom was a free and open-source text and source code editor for macOS, Linux, and Windows with support for plug-ins written in JavaScript, and embedded Git Control. Developed by GitHub, Atom was released on June 25, 2015.
Pluma is a fork of gedit 2 and the default text editor of the MATE desktop environment used in Linux distributions. It extends the basic functionality with other features and plugins.
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{{cite journal}}: CS1 maint: bot: original URL status unknown (link) Table 2: "Some Adaptable LPEs", p. 113. Same authors' abridged version in book form: Eckstein, Jutta; Baumeister, Hubert, eds. (June 2004). "Literate Programming to Enhance Agile Methods". Extreme Programming and Agile Processes in Software Engineering. Berlin; Heidelberg; New York: Springer-Verlag. pp. 250–253. ISBN 3-540-22137-9. Table 2: "Some Language Independent LPEs", p. 251{{cite journal}}: CS1 maint: bot: original URL status unknown (link) Leo discussed on pp. 12-13 of author's copy of published article.A few literate programming systems have taken a much different tack based on novel user interfaces. Edward Ream's literate editor, Leo, uses visual outlines that allow users to attach metadata and descriptions to program descriptions and data. Unfortunately, truly literate programs may break Leo's hierarchical outline based paradigm.(p. 1009)
