<!DOCTYPE HTML> <html lang="en" class="sidebar-visible no-js light"> <head> <!-- Book generated using mdBook --> <meta charset="UTF-8"> <title>Code Style - Synapse</title> <!-- Custom HTML head --> <meta content="text/html; charset=utf-8" http-equiv="Content-Type"> <meta name="description" content=""> <meta name="viewport" content="width=device-width, initial-scale=1"> <meta name="theme-color" content="#ffffff" /> <link rel="icon" href="favicon.svg"> <link rel="shortcut icon" href="favicon.png"> <link rel="stylesheet" href="css/variables.css"> <link rel="stylesheet" href="css/general.css"> <link rel="stylesheet" href="css/chrome.css"> <link rel="stylesheet" href="css/print.css" media="print"> <!-- Fonts --> <link rel="stylesheet" href="FontAwesome/css/font-awesome.css"> <link rel="stylesheet" href="fonts/fonts.css"> <!-- Highlight.js Stylesheets --> <link rel="stylesheet" href="highlight.css"> <link rel="stylesheet" href="tomorrow-night.css"> <link rel="stylesheet" href="ayu-highlight.css"> <!-- Custom theme stylesheets --> <link rel="stylesheet" href="docs/website_files/table-of-contents.css"> <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css"> <link rel="stylesheet" href="docs/website_files/indent-section-headers.css"> <link rel="stylesheet" href="docs/website_files/version-picker.css"> </head> <body> <!-- Provide site root to javascript --> <script type="text/javascript"> var path_to_root = ""; var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? 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Proxy</a></li><li class="chapter-item expanded "><a href="setup/forward_proxy.html">Configuring a Forward/Outbound Proxy</a></li><li class="chapter-item expanded "><a href="turn-howto.html">Configuring a Turn Server</a></li><li class="chapter-item expanded "><a href="delegate.html">Delegation</a></li><li class="chapter-item expanded affix "><li class="part-title">Upgrading</li><li class="chapter-item expanded "><a href="upgrade.html">Upgrading between Synapse Versions</a></li><li class="chapter-item expanded affix "><li class="part-title">Usage</li><li class="chapter-item expanded "><a href="federate.html">Federation</a></li><li class="chapter-item expanded "><a href="usage/configuration/index.html">Configuration</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="usage/configuration/config_documentation.html">Configuration Manual</a></li><li class="chapter-item expanded "><a href="usage/configuration/homeserver_sample_config.html">Homeserver Sample Config File</a></li><li class="chapter-item expanded "><a href="usage/configuration/logging_sample_config.html">Logging Sample Config File</a></li><li class="chapter-item expanded "><a href="structured_logging.html">Structured Logging</a></li><li class="chapter-item expanded "><a href="templates.html">Templates</a></li><li class="chapter-item expanded "><a href="usage/configuration/user_authentication/index.html">User Authentication</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="usage/configuration/user_authentication/single_sign_on/index.html">Single-Sign On</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="openid.html">OpenID Connect</a></li><li class="chapter-item expanded "><a href="usage/configuration/user_authentication/single_sign_on/saml.html">SAML</a></li><li class="chapter-item expanded "><a href="usage/configuration/user_authentication/single_sign_on/cas.html">CAS</a></li><li class="chapter-item expanded "><a href="sso_mapping_providers.html">SSO Mapping Providers</a></li></ol></li><li class="chapter-item expanded "><a href="password_auth_providers.html">Password Auth Providers</a></li><li class="chapter-item expanded "><a href="jwt.html">JSON Web Tokens</a></li><li class="chapter-item expanded "><a href="usage/configuration/user_authentication/refresh_tokens.html">Refresh Tokens</a></li></ol></li><li class="chapter-item expanded "><a href="CAPTCHA_SETUP.html">Registration Captcha</a></li><li class="chapter-item expanded "><a href="application_services.html">Application Services</a></li><li class="chapter-item expanded "><a href="server_notices.html">Server Notices</a></li><li class="chapter-item expanded "><a href="consent_tracking.html">Consent Tracking</a></li><li class="chapter-item expanded "><a href="development/url_previews.html">URL Previews</a></li><li class="chapter-item expanded "><a href="user_directory.html">User Directory</a></li><li class="chapter-item expanded "><a href="message_retention_policies.html">Message Retention Policies</a></li><li class="chapter-item expanded "><a href="modules/index.html">Pluggable Modules</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="modules/writing_a_module.html">Writing a module</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="modules/spam_checker_callbacks.html">Spam checker callbacks</a></li><li class="chapter-item expanded "><a href="modules/third_party_rules_callbacks.html">Third-party rules callbacks</a></li><li class="chapter-item expanded "><a href="modules/presence_router_callbacks.html">Presence router callbacks</a></li><li class="chapter-item expanded "><a href="modules/account_validity_callbacks.html">Account validity callbacks</a></li><li class="chapter-item expanded "><a href="modules/password_auth_provider_callbacks.html">Password auth provider callbacks</a></li><li class="chapter-item expanded "><a href="modules/background_update_controller_callbacks.html">Background update controller callbacks</a></li><li class="chapter-item expanded "><a href="modules/account_data_callbacks.html">Account data callbacks</a></li><li class="chapter-item expanded "><a href="modules/porting_legacy_module.html">Porting a legacy module to the new interface</a></li></ol></li></ol></li><li class="chapter-item expanded "><a href="workers.html">Workers</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="synctl_workers.html">Using synctl with Workers</a></li><li class="chapter-item expanded "><a href="systemd-with-workers/index.html">Systemd</a></li></ol></li></ol></li><li class="chapter-item expanded "><a href="usage/administration/index.html">Administration</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="usage/administration/admin_api/index.html">Admin API</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="admin_api/account_validity.html">Account Validity</a></li><li class="chapter-item expanded "><a href="usage/administration/admin_api/background_updates.html">Background Updates</a></li><li class="chapter-item expanded "><a href="admin_api/event_reports.html">Event Reports</a></li><li class="chapter-item expanded "><a href="admin_api/media_admin_api.html">Media</a></li><li class="chapter-item expanded "><a href="admin_api/purge_history_api.html">Purge History</a></li><li class="chapter-item expanded "><a href="admin_api/register_api.html">Register Users</a></li><li class="chapter-item expanded "><a href="usage/administration/admin_api/registration_tokens.html">Registration Tokens</a></li><li class="chapter-item expanded "><a href="admin_api/room_membership.html">Manipulate Room Membership</a></li><li class="chapter-item expanded "><a href="admin_api/rooms.html">Rooms</a></li><li class="chapter-item expanded "><a href="admin_api/server_notices.html">Server Notices</a></li><li class="chapter-item expanded "><a href="admin_api/statistics.html">Statistics</a></li><li class="chapter-item expanded "><a href="admin_api/user_admin_api.html">Users</a></li><li class="chapter-item expanded "><a href="admin_api/version_api.html">Server Version</a></li><li class="chapter-item expanded "><a href="usage/administration/admin_api/federation.html">Federation</a></li></ol></li><li class="chapter-item expanded "><a href="manhole.html">Manhole</a></li><li class="chapter-item expanded "><a href="metrics-howto.html">Monitoring</a></li><li class="chapter-item expanded "><a href="usage/administration/understanding_synapse_through_grafana_graphs.html">Understanding Synapse Through Grafana Graphs</a></li><li class="chapter-item expanded "><a href="usage/administration/useful_sql_for_admins.html">Useful SQL for Admins</a></li><li class="chapter-item expanded "><a href="usage/administration/database_maintenance_tools.html">Database Maintenance Tools</a></li><li class="chapter-item expanded "><a href="usage/administration/state_groups.html">State Groups</a></li><li class="chapter-item expanded "><a href="usage/administration/request_log.html">Request log format</a></li><li class="chapter-item expanded "><a href="usage/administration/admin_faq.html">Admin FAQ</a></li><li class="chapter-item expanded "><div>Scripts</div></li></ol></li><li class="chapter-item expanded "><li class="part-title">Development</li><li class="chapter-item expanded "><a href="development/contributing_guide.html">Contributing Guide</a></li><li class="chapter-item expanded "><a href="code_style.html" class="active">Code Style</a></li><li class="chapter-item expanded "><a href="development/releases.html">Release Cycle</a></li><li class="chapter-item expanded "><a href="development/git.html">Git Usage</a></li><li class="chapter-item expanded "><div>Testing</div></li><li><ol class="section"><li class="chapter-item expanded "><a href="development/demo.html">Demo scripts</a></li></ol></li><li class="chapter-item expanded "><a href="opentracing.html">OpenTracing</a></li><li class="chapter-item expanded "><a href="development/database_schema.html">Database Schemas</a></li><li class="chapter-item expanded "><a href="development/experimental_features.html">Experimental features</a></li><li class="chapter-item expanded "><a href="development/dependencies.html">Dependency management</a></li><li class="chapter-item expanded "><div>Synapse Architecture</div></li><li><ol class="section"><li class="chapter-item expanded "><a href="development/synapse_architecture/cancellation.html">Cancellation</a></li><li class="chapter-item expanded "><a href="log_contexts.html">Log Contexts</a></li><li class="chapter-item expanded "><a href="replication.html">Replication</a></li><li class="chapter-item expanded "><a href="tcp_replication.html">TCP Replication</a></li></ol></li><li class="chapter-item expanded "><a href="development/internal_documentation/index.html">Internal Documentation</a></li><li><ol class="section"><li class="chapter-item expanded "><div>Single Sign-On</div></li><li><ol class="section"><li class="chapter-item expanded "><a href="development/saml.html">SAML</a></li><li class="chapter-item expanded "><a href="development/cas.html">CAS</a></li></ol></li><li class="chapter-item expanded "><a href="development/room-dag-concepts.html">Room DAG concepts</a></li><li class="chapter-item expanded "><div>State Resolution</div></li><li><ol class="section"><li class="chapter-item expanded "><a href="auth_chain_difference_algorithm.html">The Auth Chain Difference Algorithm</a></li></ol></li><li class="chapter-item expanded "><a href="media_repository.html">Media Repository</a></li><li class="chapter-item expanded "><a href="room_and_user_statistics.html">Room and User Statistics</a></li></ol></li><li class="chapter-item expanded "><div>Scripts</div></li><li class="chapter-item expanded affix "><li class="part-title">Other</li><li class="chapter-item expanded "><a href="deprecation_policy.html">Dependency Deprecation Policy</a></li><li class="chapter-item expanded "><a href="other/running_synapse_on_single_board_computers.html">Running Synapse on a Single-Board Computer</a></li></ol> </div> <div id="sidebar-resize-handle" class="sidebar-resize-handle"></div> </nav> <div id="page-wrapper" class="page-wrapper"> <div class="page"> <div id="menu-bar-hover-placeholder"></div> <div id="menu-bar" class="menu-bar sticky bordered"> <div class="left-buttons"> <button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar"> <i class="fa fa-bars"></i> </button> <button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list"> <i class="fa fa-paint-brush"></i> </button> <ul id="theme-list" class="theme-popup" 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(Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar"> <i class="fa fa-search"></i> </button> <div class="version-picker"> <div class="dropdown"> <div class="select"> <span></span> <i class="fa fa-chevron-down"></i> </div> <input type="hidden" name="version"> <ul class="dropdown-menu"> <!-- Versions will be added dynamically in version-picker.js --> </ul> </div> </div> </div> <h1 class="menu-title">Synapse</h1> <div class="right-buttons"> <a href="print.html" title="Print this book" aria-label="Print this book"> <i id="print-button" class="fa fa-print"></i> </a> <a href="https://github.com/matrix-org/synapse" title="Git repository" aria-label="Git repository"> <i id="git-repository-button" class="fa fa-github"></i> </a> <a href="https://github.com/matrix-org/synapse/edit/develop/docs/code_style.md" title="Suggest an edit" aria-label="Suggest an edit"> <i id="git-edit-button" class="fa fa-edit"></i> </a> </div> </div> <div id="search-wrapper" class="hidden"> <form id="searchbar-outer" class="searchbar-outer"> <input type="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header"> </form> <div id="searchresults-outer" class="searchresults-outer hidden"> <div id="searchresults-header" class="searchresults-header"></div> <ul id="searchresults"> </ul> </div> </div> <!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM --> <script type="text/javascript"> document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible'); document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible'); Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) { link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1); }); </script> <div id="content" class="content"> <main> <!-- Page table of contents --> <div class="sidetoc"> <nav class="pagetoc"></nav> </div> <h1 id="code-style"><a class="header" href="#code-style">Code Style</a></h1> <h2 id="formatting-tools"><a class="header" href="#formatting-tools">Formatting tools</a></h2> <p>The Synapse codebase uses a number of code formatting tools in order to quickly and automatically check for formatting (and sometimes logical) errors in code.</p> <p>The necessary tools are:</p> <ul> <li><a href="https://black.readthedocs.io/en/stable/">black</a>, a source code formatter;</li> <li><a href="https://pycqa.github.io/isort/">isort</a>, which organises each file's imports;</li> <li><a href="https://flake8.pycqa.org/en/latest/">flake8</a>, which can spot common errors; and</li> <li><a href="https://mypy.readthedocs.io/en/stable/">mypy</a>, a type checker.</li> </ul> <p>Install them with:</p> <pre><code class="language-sh">pip install -e ".[lint,mypy]" </code></pre> <p>The easiest way to run the lints is to invoke the linter script as follows.</p> <pre><code class="language-sh">scripts-dev/lint.sh </code></pre> <p>It's worth noting that modern IDEs and text editors can run these tools automatically on save. It may be worth looking into whether this functionality is supported in your editor for a more convenient development workflow. It is not, however, recommended to run <code>flake8</code> or <code>mypy</code> on save as they take a while and can be very resource intensive.</p> <h2 id="general-rules"><a class="header" href="#general-rules">General rules</a></h2> <ul> <li><strong>Naming</strong>: <ul> <li>Use <code>CamelCase</code> for class and type names</li> <li>Use underscores for <code>function_names</code> and <code>variable_names</code>.</li> </ul> </li> <li><strong>Docstrings</strong>: should follow the <a href="https://google.github.io/styleguide/pyguide.html#38-comments-and-docstrings">google code style</a>. See the <a href="http://sphinxcontrib-napoleon.readthedocs.io/en/latest/example_google.html">examples</a> in the sphinx documentation.</li> <li><strong>Imports</strong>: <ul> <li> <p>Imports should be sorted by <code>isort</code> as described above.</p> </li> <li> <p>Prefer to import classes and functions rather than packages or modules.</p> <p>Example:</p> <pre><code class="language-python">from synapse.types import UserID ... user_id = UserID(local, server) </code></pre> <p>is preferred over:</p> <pre><code class="language-python">from synapse import types ... user_id = types.UserID(local, server) </code></pre> <p>(or any other variant).</p> <p>This goes against the advice in the Google style guide, but it means that errors in the name are caught early (at import time).</p> </li> <li> <p>Avoid wildcard imports (<code>from synapse.types import *</code>) and relative imports (<code>from .types import UserID</code>).</p> </li> </ul> </li> </ul> <h2 id="configuration-file-format"><a class="header" href="#configuration-file-format">Configuration file format</a></h2> <p>The <a href="./sample_config.yaml">sample configuration file</a> acts as a reference to Synapse's configuration options for server administrators. Remember that many readers will be unfamiliar with YAML and server administration in general, so that it is important that the file be as easy to understand as possible, which includes following a consistent format.</p> <p>Some guidelines follow:</p> <ul> <li> <p>Sections should be separated with a heading consisting of a single line prefixed and suffixed with <code>##</code>. There should be <strong>two</strong> blank lines before the section header, and <strong>one</strong> after.</p> </li> <li> <p>Each option should be listed in the file with the following format:</p> <ul> <li> <p>A comment describing the setting. Each line of this comment should be prefixed with a hash (<code>#</code>) and a space.</p> <p>The comment should describe the default behaviour (ie, what happens if the setting is omitted), as well as what the effect will be if the setting is changed.</p> <p>Often, the comment end with something like "uncomment the following to <do action>".</p> </li> <li> <p>A line consisting of only <code>#</code>.</p> </li> <li> <p>A commented-out example setting, prefixed with only <code>#</code>.</p> <p>For boolean (on/off) options, convention is that this example should be the <em>opposite</em> to the default (so the comment will end with "Uncomment the following to enable [or disable] <feature>." For other options, the example should give some non-default value which is likely to be useful to the reader.</p> </li> </ul> </li> <li> <p>There should be a blank line between each option.</p> </li> <li> <p>Where several settings are grouped into a single dict, <em>avoid</em> the convention where the whole block is commented out, resulting in comment lines starting <code># #</code>, as this is hard to read and confusing to edit. Instead, leave the top-level config option uncommented, and follow the conventions above for sub-options. Ensure that your code correctly handles the top-level option being set to <code>None</code> (as it will be if no sub-options are enabled).</p> </li> <li> <p>Lines should be wrapped at 80 characters.</p> </li> <li> <p>Use two-space indents.</p> </li> <li> <p><code>true</code> and <code>false</code> are spelt thus (as opposed to <code>True</code>, etc.)</p> </li> <li> <p>Use single quotes (<code>'</code>) rather than double-quotes (<code>"</code>) or backticks (<code>`</code>) to refer to configuration options.</p> </li> </ul> <p>Example:</p> <pre><code class="language-yaml">## Frobnication ## # The frobnicator will ensure that all requests are fully frobnicated. # To enable it, uncomment the following. # #frobnicator_enabled: true # By default, the frobnicator will frobnicate with the default frobber. # The following will make it use an alternative frobber. # #frobincator_frobber: special_frobber # Settings for the frobber # frobber: # frobbing speed. Defaults to 1. # #speed: 10 # frobbing distance. Defaults to 1000. # #distance: 100 </code></pre> <p>Note that the sample configuration is generated from the synapse code and is maintained by a script, <code>scripts-dev/generate_sample_config.sh</code>. Making sure that the output from this script matches the desired format is left as an exercise for the reader!</p> </main> <nav class="nav-wrapper" aria-label="Page navigation"> <!-- Mobile navigation buttons --> <a rel="prev" href="development/contributing_guide.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> <i class="fa fa-angle-left"></i> </a> <a rel="next" href="development/releases.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> <i class="fa fa-angle-right"></i> </a> <div style="clear: both"></div> </nav> </div> </div> <nav class="nav-wide-wrapper" aria-label="Page navigation"> <a rel="prev" href="development/contributing_guide.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> <i class="fa fa-angle-left"></i> </a> <a rel="next" href="development/releases.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> <i class="fa fa-angle-right"></i> </a> </nav> </div> <script type="text/javascript"> window.playground_copyable = true; </script> <script src="elasticlunr.min.js" type="text/javascript" charset="utf-8"></script> <script src="mark.min.js" type="text/javascript" charset="utf-8"></script> <script src="searcher.js" type="text/javascript" charset="utf-8"></script> <script src="clipboard.min.js" type="text/javascript" charset="utf-8"></script> <script src="highlight.js" type="text/javascript" charset="utf-8"></script> <script src="book.js" type="text/javascript" charset="utf-8"></script> <!-- Custom JS scripts --> <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script> <script type="text/javascript" src="docs/website_files/version-picker.js"></script> <script type="text/javascript" src="docs/website_files/version.js"></script> </body> </html>