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355 lines
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<a href='../env_logger/index.html'><img src='http://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png' alt='logo' width='100'></a>
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<p class='location'>Crate env_logger</p><div class="sidebar-elems"><div class="block items"><ul><li><a href="#reexports">Re-exports</a></li><li><a href="#modules">Modules</a></li><li><a href="#structs">Structs</a></li><li><a href="#constants">Constants</a></li><li><a href="#functions">Functions</a></li></ul></div><p class='location'></p><script>window.sidebarCurrent = {name: 'env_logger', ty: 'mod', relpath: '../'};</script></div>
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<section id='main' class="content"><h1 class='fqn'><span class='in-band'>Crate <a class="mod" href=''>env_logger</a></span><span class='out-of-band'><span id='render-detail'>
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<a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">
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[<span class='inner'>−</span>]
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</a>
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</span><a class='srclink' href='../src/env_logger/lib.rs.html#11-1099' title='goto source code'>[src]</a></span></h1><div class='docblock'><p>A simple logger configured via environment variables which writes
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to stdout or stderr, for use with the logging facade exposed by the
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<a href="https://docs.rs/log/"><code>log</code> crate</a>.</p>
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<h2 id="example" class="section-header"><a href="#example">Example</a></h2>
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<pre class="rust rust-example-rendered">
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<span class="attribute">#[<span class="ident">macro_use</span>]</span> <span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">log</span>;
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<span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">env_logger</span>;
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<span class="kw">use</span> <span class="ident">log</span>::<span class="ident">Level</span>;
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<span class="kw">fn</span> <span class="ident">main</span>() {
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<span class="ident">env_logger</span>::<span class="ident">init</span>();
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<span class="macro">debug</span><span class="macro">!</span>(<span class="string">"this is a debug {}"</span>, <span class="string">"message"</span>);
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<span class="macro">error</span><span class="macro">!</span>(<span class="string">"this is printed by default"</span>);
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<span class="kw">if</span> <span class="macro">log_enabled</span><span class="macro">!</span>(<span class="ident">Level</span>::<span class="ident">Info</span>) {
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<span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="number">3</span> <span class="op">*</span> <span class="number">4</span>; <span class="comment">// expensive computation</span>
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<span class="macro">info</span><span class="macro">!</span>(<span class="string">"the answer was: {}"</span>, <span class="ident">x</span>);
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}
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}</pre>
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<p>Assumes the binary is <code>main</code>:</p>
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<pre><code class="language-{.bash}">$ RUST_LOG=error ./main
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ERROR: 2017-11-09T02:12:24Z: main: this is printed by default
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</code></pre>
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<pre><code class="language-{.bash}">$ RUST_LOG=info ./main
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ERROR: 2017-11-09T02:12:24Z: main: this is printed by default
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INFO: 2017-11-09T02:12:24Z: main: the answer was: 12
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</code></pre>
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<pre><code class="language-{.bash}">$ RUST_LOG=debug ./main
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DEBUG: 2017-11-09T02:12:24Z: main: this is a debug message
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ERROR: 2017-11-09T02:12:24Z: main: this is printed by default
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INFO: 2017-11-09T02:12:24Z: main: the answer was: 12
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</code></pre>
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<p>You can also set the log level on a per module basis:</p>
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<pre><code class="language-{.bash}">$ RUST_LOG=main=info ./main
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ERROR: 2017-11-09T02:12:24Z: main: this is printed by default
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INFO: 2017-11-09T02:12:24Z: main: the answer was: 12
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</code></pre>
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<p>And enable all logging:</p>
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<pre><code class="language-{.bash}">$ RUST_LOG=main ./main
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DEBUG: 2017-11-09T02:12:24Z: main: this is a debug message
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ERROR: 2017-11-09T02:12:24Z: main: this is printed by default
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INFO: 2017-11-09T02:12:24Z: main: the answer was: 12
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</code></pre>
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<p>If the binary name contains hyphens, you will need to replace
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them with underscores:</p>
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<pre><code class="language-{.bash}">$ RUST_LOG=my_app ./my-app
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DEBUG: 2017-11-09T02:12:24Z: my_app: this is a debug message
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ERROR: 2017-11-09T02:12:24Z: my_app: this is printed by default
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INFO: 2017-11-09T02:12:24Z: my_app: the answer was: 12
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</code></pre>
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<p>This is because Rust modules and crates cannot contain hyphens
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in their name, although <code>cargo</code> continues to accept them.</p>
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<p>See the documentation for the <a href="https://docs.rs/log/"><code>log</code> crate</a> for more
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information about its API.</p>
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<h2 id="enabling-logging" class="section-header"><a href="#enabling-logging">Enabling logging</a></h2>
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<p>Log levels are controlled on a per-module basis, and by default all logging
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is disabled except for <code>error!</code>. Logging is controlled via the <code>RUST_LOG</code>
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environment variable. The value of this environment variable is a
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comma-separated list of logging directives. A logging directive is of the
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form:</p>
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<pre><code class="language-text">path::to::module=level
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</code></pre>
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<p>The path to the module is rooted in the name of the crate it was compiled
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for, so if your program is contained in a file <code>hello.rs</code>, for example, to
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turn on logging for this file you would use a value of <code>RUST_LOG=hello</code>.
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Furthermore, this path is a prefix-search, so all modules nested in the
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specified module will also have logging enabled.</p>
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<p>The actual <code>level</code> is optional to specify. If omitted, all logging will
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be enabled. If specified, it must be one of the strings <code>debug</code>, <code>error</code>,
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<code>info</code>, <code>warn</code>, or <code>trace</code>.</p>
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<p>As the log level for a module is optional, the module to enable logging for
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is also optional. If only a <code>level</code> is provided, then the global log
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level for all modules is set to this value.</p>
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<p>Some examples of valid values of <code>RUST_LOG</code> are:</p>
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<ul>
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<li><code>hello</code> turns on all logging for the 'hello' module</li>
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<li><code>info</code> turns on all info logging</li>
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<li><code>hello=debug</code> turns on debug logging for 'hello'</li>
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<li><code>hello,std::option</code> turns on hello, and std's option logging</li>
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<li><code>error,hello=warn</code> turn on global error logging and also warn for hello</li>
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</ul>
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<h2 id="filtering-results" class="section-header"><a href="#filtering-results">Filtering results</a></h2>
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<p>A <code>RUST_LOG</code> directive may include a regex filter. The syntax is to append <code>/</code>
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followed by a regex. Each message is checked against the regex, and is only
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logged if it matches. Note that the matching is done after formatting the
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log string but before adding any logging meta-data. There is a single filter
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for all modules.</p>
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<p>Some examples:</p>
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<ul>
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<li><code>hello/foo</code> turns on all logging for the 'hello' module where the log
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message includes 'foo'.</li>
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<li><code>info/f.o</code> turns on all info logging where the log message includes 'foo',
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'f1o', 'fao', etc.</li>
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<li><code>hello=debug/foo*foo</code> turns on debug logging for 'hello' where the log
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message includes 'foofoo' or 'fofoo' or 'fooooooofoo', etc.</li>
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<li><code>error,hello=warn/[0-9]scopes</code> turn on global error logging and also
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warn for hello. In both cases the log message must include a single digit
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number followed by 'scopes'.</li>
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</ul>
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<h2 id="disabling-colors" class="section-header"><a href="#disabling-colors">Disabling colors</a></h2>
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<p>Colors and other styles can be configured with the <code>RUST_LOG_STYLE</code>
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environment variable. It accepts the following values:</p>
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<ul>
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<li><code>auto</code> (default) will attempt to print style characters, but don't force the issue.
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If the console isn't available on Windows, or if TERM=dumb, for example, then don't print colors.</li>
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<li><code>always</code> will always print style characters even if they aren't supported by the terminal.
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This includes emitting ANSI colors on Windows if the console API is unavailable.</li>
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<li><code>never</code> will never print style characters.</li>
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</ul>
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<h2 id="tweaking-the-default-format" class="section-header"><a href="#tweaking-the-default-format">Tweaking the default format</a></h2>
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<p>Parts of the default format can be excluded from the log output using the <a href="struct.Builder.html"><code>Builder</code></a>.
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The following example excluding the timestamp from the log output:</p>
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<pre class="rust rust-example-rendered">
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<span class="attribute">#[<span class="ident">macro_use</span>]</span> <span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">log</span>;
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<span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">env_logger</span>;
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|
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<span class="kw">use</span> <span class="ident">log</span>::<span class="ident">Level</span>;
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<span class="kw">fn</span> <span class="ident">main</span>() {
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<span class="ident">env_logger</span>::<span class="ident">Builder</span>::<span class="ident">from_default_env</span>()
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.<span class="ident">default_format_timestamp</span>(<span class="bool-val">false</span>)
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.<span class="ident">init</span>();
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<span class="macro">debug</span><span class="macro">!</span>(<span class="string">"this is a debug {}"</span>, <span class="string">"message"</span>);
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<span class="macro">error</span><span class="macro">!</span>(<span class="string">"this is printed by default"</span>);
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<span class="kw">if</span> <span class="macro">log_enabled</span><span class="macro">!</span>(<span class="ident">Level</span>::<span class="ident">Info</span>) {
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<span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="number">3</span> <span class="op">*</span> <span class="number">4</span>; <span class="comment">// expensive computation</span>
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<span class="macro">info</span><span class="macro">!</span>(<span class="string">"the answer was: {}"</span>, <span class="ident">x</span>);
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}
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}</pre>
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</div><h2 id='reexports' class='section-header'><a href="#reexports">Re-exports</a></h2>
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<table><tr><td><code>pub use self::fmt::<a class="enum" href="../env_logger/fmt/enum.Target.html" title="enum env_logger::fmt::Target">Target</a>;</code></td></tr><tr><td><code>pub use self::fmt::<a class="enum" href="../env_logger/fmt/enum.WriteStyle.html" title="enum env_logger::fmt::WriteStyle">WriteStyle</a>;</code></td></tr><tr><td><code>pub use self::fmt::<a class="enum" href="../env_logger/fmt/enum.Color.html" title="enum env_logger::fmt::Color">Color</a>;</code></td></tr><tr><td><code>pub use self::fmt::<a class="struct" href="../env_logger/fmt/struct.Formatter.html" title="struct env_logger::fmt::Formatter">Formatter</a>;</code></td></tr></table><h2 id='modules' class='section-header'><a href="#modules">Modules</a></h2>
|
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<table>
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<tr class=' module-item'>
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<td><a class="mod" href="filter/index.html"
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title='mod env_logger::filter'>filter</a></td>
|
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|
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<td class='docblock-short'>
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<p>Filtering for log records.</p>
|
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|
|
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</td>
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|
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</tr>
|
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|
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<tr class=' module-item'>
|
|||
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<td><a class="mod" href="fmt/index.html"
|
|||
|
|
title='mod env_logger::fmt'>fmt</a></td>
|
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|
|
<td class='docblock-short'>
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<p>Formatting for log records.</p>
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|
|
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</td>
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</tr></table><h2 id='structs' class='section-header'><a href="#structs">Structs</a></h2>
|
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<table>
|
|||
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<tr class=' module-item'>
|
|||
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|
<td><a class="struct" href="struct.Builder.html"
|
|||
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title='struct env_logger::Builder'>Builder</a></td>
|
|||
|
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<td class='docblock-short'>
|
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|
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<p><code>Builder</code> acts as builder for initializing a <code>Logger</code>.</p>
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|
|
|
|||
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</td>
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</tr>
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<tr class=' module-item'>
|
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<td><a class="struct" href="struct.Env.html"
|
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title='struct env_logger::Env'>Env</a></td>
|
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|
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<td class='docblock-short'>
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<p>Set of environment variables to configure from.</p>
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|
|
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</td>
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</tr>
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<tr class=' module-item'>
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|||
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<td><a class="struct" href="struct.Logger.html"
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|
title='struct env_logger::Logger'>Logger</a></td>
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<td class='docblock-short'>
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<p>The env logger.</p>
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|
|
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</td>
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</tr></table><h2 id='constants' class='section-header'><a href="#constants">Constants</a></h2>
|
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<table>
|
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<tr class=' module-item'>
|
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<td><a class="constant" href="constant.DEFAULT_FILTER_ENV.html"
|
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title='constant env_logger::DEFAULT_FILTER_ENV'>DEFAULT_FILTER_ENV</a></td>
|
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<td class='docblock-short'>
|
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<p>The default name for the environment variable to read filters from.</p>
|
|||
|
|
|
|||
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</td>
|
|||
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</tr>
|
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<tr class=' module-item'>
|
|||
|
|
<td><a class="constant" href="constant.DEFAULT_WRITE_STYLE_ENV.html"
|
|||
|
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title='constant env_logger::DEFAULT_WRITE_STYLE_ENV'>DEFAULT_WRITE_STYLE_ENV</a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>The default name for the environment variable to read style preferences from.</p>
|
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|
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|
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</td>
|
|||
|
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</tr></table><h2 id='functions' class='section-header'><a href="#functions">Functions</a></h2>
|
|||
|
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<table>
|
|||
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<tr class=' module-item'>
|
|||
|
|
<td><a class="fn" href="fn.init.html"
|
|||
|
|
title='fn env_logger::init'>init</a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>Initializes the global logger with an env logger.</p>
|
|||
|
|
|
|||
|
|
</td>
|
|||
|
|
</tr>
|
|||
|
|
<tr class=' module-item'>
|
|||
|
|
<td><a class="fn" href="fn.init_from_env.html"
|
|||
|
|
title='fn env_logger::init_from_env'>init_from_env</a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>Initializes the global logger with an env logger from the given environment
|
|||
|
|
variables.</p>
|
|||
|
|
|
|||
|
|
</td>
|
|||
|
|
</tr>
|
|||
|
|
<tr class=' module-item'>
|
|||
|
|
<td><a class="fn" href="fn.try_init.html"
|
|||
|
|
title='fn env_logger::try_init'>try_init</a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>Attempts to initialize the global logger with an env logger.</p>
|
|||
|
|
|
|||
|
|
</td>
|
|||
|
|
</tr>
|
|||
|
|
<tr class=' module-item'>
|
|||
|
|
<td><a class="fn" href="fn.try_init_from_env.html"
|
|||
|
|
title='fn env_logger::try_init_from_env'>try_init_from_env</a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>Attempts to initialize the global logger with an env logger from the given
|
|||
|
|
environment variables.</p>
|
|||
|
|
|
|||
|
|
</td>
|
|||
|
|
</tr></table></section>
|
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<section id='search' class="content hidden"></section>
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<h1 class="hidden">Help</h1>
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|
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<div class="shortcuts">
|
|||
|
|
<h2>Keyboard Shortcuts</h2>
|
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<dl>
|
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<dt><kbd>?</kbd></dt>
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<dd>Show this help dialog</dd>
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<dt><kbd>S</kbd></dt>
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<dd>Focus the search field</dd>
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<dt><kbd>↑</kbd></dt>
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<dd>Move up in search results</dd>
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<dd>Move down in search results</dd>
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<dd>Switch tab</dd>
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<dt><kbd>⏎</kbd></dt>
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</dl>
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</div>
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<div class="infos">
|
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|
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<h2>Search Tricks</h2>
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|
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<p>
|
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|
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Prefix searches with a type followed by a colon (e.g.
|
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<code>fn:</code>) to restrict the search to a given type.
|
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</p>
|
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|
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|
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<p>
|
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|
|
Accepted types are: <code>fn</code>, <code>mod</code>,
|
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|
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<code>struct</code>, <code>enum</code>,
|
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|
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<code>trait</code>, <code>type</code>, <code>macro</code>,
|
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|
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and <code>const</code>.
|
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</p>
|
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|
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|
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<p>
|
|||
|
|
Search functions by type signature (e.g.
|
|||
|
|
<code>vec -> usize</code> or <code>* -> vec</code>)
|
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</p>
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|
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</div>
|
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</div>
|
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</aside>
|
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|
|||
|
|
<script>
|
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|
|
window.rootPath = "../";
|
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|
|
window.currentCrate = "env_logger";
|
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</script>
|
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<script src="../main.js"></script>
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<script defer src="../search-index.js"></script>
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