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<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate"><span class="pre">string.templatelib</span></code> — Support for template string literals</a><ul>
<li><a class="reference internal" href="#template-strings">Template strings</a></li>
<li><a class="reference internal" href="#types">Types</a></li>
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  <section id="module-string.templatelib">
<span id="string-templatelib-support-for-template-string-literals"></span><h1><code class="xref py py-mod docutils literal notranslate"><span class="pre">string.templatelib</span></code> — Support for template string literals<a class="headerlink" href="#module-string.templatelib" title="Link to this heading">¶</a></h1>
<p><strong>Source code:</strong> <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/3.14/Lib/string/templatelib.py">Lib/string/templatelib.py</a></p>
<hr class="docutils" />
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<ul class="simple">
<li><p><a class="reference internal" href="../reference/lexical_analysis.html#f-strings"><span class="std std-ref">Format strings</span></a></p></li>
<li><p><a class="reference internal" href="../reference/lexical_analysis.html#t-strings"><span class="std std-ref">Template string literal (t-string) syntax</span></a></p></li>
<li><p><span class="target" id="index-0"></span><a class="pep reference external" href="https://peps.python.org/pep-0750/"><strong>PEP 750</strong></a></p></li>
</ul>
</div>
<section id="template-strings">
<span id="id1"></span><h2>Template strings<a class="headerlink" href="#template-strings" title="Link to this heading">¶</a></h2>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.14.</span></p>
</div>
<p>Template strings are a mechanism for custom string processing.
They have the full flexibility of Python’s <a class="reference internal" href="../reference/lexical_analysis.html#f-strings"><span class="std std-ref">f-strings</span></a>,
but return a <a class="reference internal" href="#string.templatelib.Template" title="string.templatelib.Template"><code class="xref py py-class docutils literal notranslate"><span class="pre">Template</span></code></a> instance that gives access
to the static and interpolated (in curly brackets) parts of a string
<em>before</em> they are combined.</p>
<p>To write a t-string, use a <code class="docutils literal notranslate"><span class="pre">'t'</span></code> prefix instead of an <code class="docutils literal notranslate"><span class="pre">'f'</span></code>, like so:</p>
<div class="highlight-pycon notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">pi</span> <span class="o">=</span> <span class="mf">3.14</span>
<span class="gp">&gt;&gt;&gt; </span><span class="sa">t</span><span class="s1">&#39;t-strings are new in Python </span><span class="si">{</span><span class="n">pi</span><span class="si">!s}</span><span class="s1">!&#39;</span>
<span class="go">Template(</span>
<span class="go">   strings=(&#39;t-strings are new in Python &#39;, &#39;!&#39;),</span>
<span class="go">   interpolations=(Interpolation(3.14, &#39;pi&#39;, &#39;s&#39;, &#39;&#39;),)</span>
<span class="go">)</span>
</pre></div>
</div>
</section>
<section id="types">
<h2>Types<a class="headerlink" href="#types" title="Link to this heading">¶</a></h2>
<dl class="py class">
<dt class="sig sig-object py" id="string.templatelib.Template">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">string.templatelib.</span></span><span class="sig-name descname"><span class="pre">Template</span></span><a class="headerlink" href="#string.templatelib.Template" title="Link to this definition">¶</a></dt>
<dd><p>The <code class="xref py py-class docutils literal notranslate"><span class="pre">Template</span></code> class describes the contents of a template string.
It is immutable, meaning that attributes of a template cannot be reassigned.</p>
<p>The most common way to create a <code class="xref py py-class docutils literal notranslate"><span class="pre">Template</span></code> instance is to use the
<a class="reference internal" href="../reference/lexical_analysis.html#t-strings"><span class="std std-ref">template string literal syntax</span></a>.
This syntax is identical to that of <a class="reference internal" href="../reference/lexical_analysis.html#f-strings"><span class="std std-ref">f-strings</span></a>,
except that it uses a <code class="docutils literal notranslate"><span class="pre">t</span></code> prefix in place of an <code class="docutils literal notranslate"><span class="pre">f</span></code>:</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">cheese</span> <span class="o">=</span> <span class="s1">&#39;Red Leicester&#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span> <span class="o">=</span> <span class="sa">t</span><span class="s2">&quot;We&#39;re fresh out of </span><span class="si">{</span><span class="n">cheese</span><span class="si">}</span><span class="s2">, sir.&quot;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="nb">type</span><span class="p">(</span><span class="n">template</span><span class="p">)</span>
<span class="go">&lt;class &#39;string.templatelib.Template&#39;&gt;</span>
</pre></div>
</div>
<p>Templates are stored as sequences of literal <a class="reference internal" href="#string.templatelib.Template.strings" title="string.templatelib.Template.strings"><code class="xref py py-attr docutils literal notranslate"><span class="pre">strings</span></code></a>
and dynamic <a class="reference internal" href="#string.templatelib.Template.interpolations" title="string.templatelib.Template.interpolations"><code class="xref py py-attr docutils literal notranslate"><span class="pre">interpolations</span></code></a>.
A <a class="reference internal" href="#string.templatelib.Template.values" title="string.templatelib.Template.values"><code class="xref py py-attr docutils literal notranslate"><span class="pre">values</span></code></a> attribute holds the values of the interpolations:</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">cheese</span> <span class="o">=</span> <span class="s1">&#39;Camembert&#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span> <span class="o">=</span> <span class="sa">t</span><span class="s1">&#39;Ah! We do have </span><span class="si">{</span><span class="n">cheese</span><span class="si">}</span><span class="s1">.&#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span><span class="o">.</span><span class="n">strings</span>
<span class="go">(&#39;Ah! We do have &#39;, &#39;.&#39;)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span><span class="o">.</span><span class="n">interpolations</span>
<span class="go">(Interpolation(&#39;Camembert&#39;, ...),)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span><span class="o">.</span><span class="n">values</span>
<span class="go">(&#39;Camembert&#39;,)</span>
</pre></div>
</div>
<p>The <code class="xref py py-attr docutils literal notranslate"><span class="pre">strings</span></code> tuple has one more element than <code class="xref py py-attr docutils literal notranslate"><span class="pre">interpolations</span></code>
and <code class="xref py py-attr docutils literal notranslate"><span class="pre">values</span></code>; the interpolations “belong” between the strings.
This may be easier to understand when tuples are aligned</p>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="n">template</span><span class="o">.</span><span class="n">strings</span><span class="p">:</span>  <span class="p">(</span><span class="s1">&#39;Ah! We do have &#39;</span><span class="p">,</span>              <span class="s1">&#39;.&#39;</span><span class="p">)</span>
<span class="n">template</span><span class="o">.</span><span class="n">values</span><span class="p">:</span>   <span class="p">(</span>                   <span class="s1">&#39;Camembert&#39;</span><span class="p">,</span>    <span class="p">)</span>
</pre></div>
</div>
<p class="rubric">Attributes</p>
<dl class="py attribute">
<dt class="sig sig-object py" id="string.templatelib.Template.strings">
<span class="sig-name descname"><span class="pre">strings</span></span><em class="property"><span class="p"><span class="pre">:</span></span><span class="w"> </span><a class="reference internal" href="stdtypes.html#tuple" title="tuple"><span class="pre">tuple</span></a><span class="p"><span class="pre">[</span></span><a class="reference internal" href="stdtypes.html#str" title="str"><span class="pre">str</span></a><span class="p"><span class="pre">,</span></span><span class="w"> </span><span class="p"><span class="pre">...</span></span><span class="p"><span class="pre">]</span></span></em><a class="headerlink" href="#string.templatelib.Template.strings" title="Link to this definition">¶</a></dt>
<dd><p>A <a class="reference internal" href="stdtypes.html#tuple" title="tuple"><code class="xref py py-class docutils literal notranslate"><span class="pre">tuple</span></code></a> of the static strings in the template.</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">cheese</span> <span class="o">=</span> <span class="s1">&#39;Camembert&#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span> <span class="o">=</span> <span class="sa">t</span><span class="s1">&#39;Ah! We do have </span><span class="si">{</span><span class="n">cheese</span><span class="si">}</span><span class="s1">.&#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span><span class="o">.</span><span class="n">strings</span>
<span class="go">(&#39;Ah! We do have &#39;, &#39;.&#39;)</span>
</pre></div>
</div>
<p>Empty strings <em>are</em> included in the tuple:</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">response</span> <span class="o">=</span> <span class="s1">&#39;We do have &#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">cheese</span> <span class="o">=</span> <span class="s1">&#39;Camembert&#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span> <span class="o">=</span> <span class="sa">t</span><span class="s1">&#39;Ah! </span><span class="si">{</span><span class="n">response</span><span class="si">}{</span><span class="n">cheese</span><span class="si">}</span><span class="s1">.&#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span><span class="o">.</span><span class="n">strings</span>
<span class="go">(&#39;Ah! &#39;, &#39;&#39;, &#39;.&#39;)</span>
</pre></div>
</div>
<p>The <code class="docutils literal notranslate"><span class="pre">strings</span></code> tuple is never empty, and always contains one more
string than the <code class="docutils literal notranslate"><span class="pre">interpolations</span></code> and <code class="docutils literal notranslate"><span class="pre">values</span></code> tuples:</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="sa">t</span><span class="s1">&#39;&#39;</span><span class="o">.</span><span class="n">strings</span>
<span class="go">(&#39;&#39;,)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="sa">t</span><span class="s1">&#39;&#39;</span><span class="o">.</span><span class="n">values</span>
<span class="go">()</span>
<span class="gp">&gt;&gt;&gt; </span><span class="sa">t</span><span class="s1">&#39;</span><span class="si">{</span><span class="s1">&#39;cheese&#39;</span><span class="si">}</span><span class="s1">&#39;</span><span class="o">.</span><span class="n">strings</span>
<span class="go">(&#39;&#39;, &#39;&#39;)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="sa">t</span><span class="s1">&#39;</span><span class="si">{</span><span class="s1">&#39;cheese&#39;</span><span class="si">}</span><span class="s1">&#39;</span><span class="o">.</span><span class="n">values</span>
<span class="go">(&#39;cheese&#39;,)</span>
</pre></div>
</div>
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="string.templatelib.Template.interpolations">
<span class="sig-name descname"><span class="pre">interpolations</span></span><em class="property"><span class="p"><span class="pre">:</span></span><span class="w"> </span><a class="reference internal" href="stdtypes.html#tuple" title="tuple"><span class="pre">tuple</span></a><span class="p"><span class="pre">[</span></span><a class="reference internal" href="#string.templatelib.Interpolation" title="string.templatelib.Interpolation"><span class="pre">Interpolation</span></a><span class="p"><span class="pre">,</span></span><span class="w"> </span><span class="p"><span class="pre">...</span></span><span class="p"><span class="pre">]</span></span></em><a class="headerlink" href="#string.templatelib.Template.interpolations" title="Link to this definition">¶</a></dt>
<dd><p>A <a class="reference internal" href="stdtypes.html#tuple" title="tuple"><code class="xref py py-class docutils literal notranslate"><span class="pre">tuple</span></code></a> of the interpolations in the template.</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">cheese</span> <span class="o">=</span> <span class="s1">&#39;Camembert&#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span> <span class="o">=</span> <span class="sa">t</span><span class="s1">&#39;Ah! We do have </span><span class="si">{</span><span class="n">cheese</span><span class="si">}</span><span class="s1">.&#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span><span class="o">.</span><span class="n">interpolations</span>
<span class="go">(Interpolation(&#39;Camembert&#39;, &#39;cheese&#39;, None, &#39;&#39;),)</span>
</pre></div>
</div>
<p>The <code class="docutils literal notranslate"><span class="pre">interpolations</span></code> tuple may be empty and always contains one fewer
values than the <code class="docutils literal notranslate"><span class="pre">strings</span></code> tuple:</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="sa">t</span><span class="s1">&#39;Red Leicester&#39;</span><span class="o">.</span><span class="n">interpolations</span>
<span class="go">()</span>
</pre></div>
</div>
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="string.templatelib.Template.values">
<span class="sig-name descname"><span class="pre">values</span></span><em class="property"><span class="p"><span class="pre">:</span></span><span class="w"> </span><a class="reference internal" href="stdtypes.html#tuple" title="tuple"><span class="pre">tuple</span></a><span class="p"><span class="pre">[</span></span><a class="reference internal" href="functions.html#object" title="object"><span class="pre">object</span></a><span class="p"><span class="pre">,</span></span><span class="w"> </span><span class="p"><span class="pre">...</span></span><span class="p"><span class="pre">]</span></span></em><a class="headerlink" href="#string.templatelib.Template.values" title="Link to this definition">¶</a></dt>
<dd><p>A tuple of all interpolated values in the template.</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">cheese</span> <span class="o">=</span> <span class="s1">&#39;Camembert&#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span> <span class="o">=</span> <span class="sa">t</span><span class="s1">&#39;Ah! We do have </span><span class="si">{</span><span class="n">cheese</span><span class="si">}</span><span class="s1">.&#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span><span class="o">.</span><span class="n">values</span>
<span class="go">(&#39;Camembert&#39;,)</span>
</pre></div>
</div>
<p>The <code class="docutils literal notranslate"><span class="pre">values</span></code> tuple always has the same length as the
<code class="docutils literal notranslate"><span class="pre">interpolations</span></code> tuple. It is always equivalent to
<code class="docutils literal notranslate"><span class="pre">tuple(i.value</span> <span class="pre">for</span> <span class="pre">i</span> <span class="pre">in</span> <span class="pre">template.interpolations)</span></code>.</p>
</dd></dl>

<p class="rubric">Methods</p>
<dl class="py method">
<dt class="sig sig-object py" id="string.templatelib.Template.__new__">
<span class="sig-name descname"><span class="pre">__new__</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="o"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span><span class="p"><span class="pre">:</span></span><span class="w"> </span><span class="n"><a class="reference internal" href="stdtypes.html#str" title="str"><span class="pre">str</span></a><span class="w"> </span><span class="p"><span class="pre">|</span></span><span class="w"> </span><a class="reference internal" href="#string.templatelib.Interpolation" title="string.templatelib.Interpolation"><span class="pre">Interpolation</span></a></span></em><span class="sig-paren">)</span><a class="headerlink" href="#string.templatelib.Template.__new__" title="Link to this definition">¶</a></dt>
<dd><p>While literal syntax is the most common way to create a <code class="xref py py-class docutils literal notranslate"><span class="pre">Template</span></code>,
it is also possible to create them directly using the constructor:</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span><span class="w"> </span><span class="nn">string.templatelib</span><span class="w"> </span><span class="kn">import</span> <span class="n">Interpolation</span><span class="p">,</span> <span class="n">Template</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">cheese</span> <span class="o">=</span> <span class="s1">&#39;Camembert&#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span> <span class="o">=</span> <span class="n">Template</span><span class="p">(</span>
<span class="gp">... </span>    <span class="s1">&#39;Ah! We do have &#39;</span><span class="p">,</span> <span class="n">Interpolation</span><span class="p">(</span><span class="n">cheese</span><span class="p">,</span> <span class="s1">&#39;cheese&#39;</span><span class="p">),</span> <span class="s1">&#39;.&#39;</span>
<span class="gp">... </span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="nb">list</span><span class="p">(</span><span class="n">template</span><span class="p">)</span>
<span class="go">[&#39;Ah! We do have &#39;, Interpolation(&#39;Camembert&#39;, &#39;cheese&#39;, None, &#39;&#39;), &#39;.&#39;]</span>
</pre></div>
</div>
<p>If multiple strings are passed consecutively, they will be concatenated
into a single value in the <a class="reference internal" href="#string.templatelib.Template.strings" title="string.templatelib.Template.strings"><code class="xref py py-attr docutils literal notranslate"><span class="pre">strings</span></code></a> attribute. For example,
the following code creates a <code class="xref py py-class docutils literal notranslate"><span class="pre">Template</span></code> with a single final string:</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span><span class="w"> </span><span class="nn">string.templatelib</span><span class="w"> </span><span class="kn">import</span> <span class="n">Template</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span> <span class="o">=</span> <span class="n">Template</span><span class="p">(</span><span class="s1">&#39;Ah! We do have &#39;</span><span class="p">,</span> <span class="s1">&#39;Camembert&#39;</span><span class="p">,</span> <span class="s1">&#39;.&#39;</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span><span class="o">.</span><span class="n">strings</span>
<span class="go">(&#39;Ah! We do have Camembert.&#39;,)</span>
</pre></div>
</div>
<p>If multiple interpolations are passed consecutively, they will be treated
as separate interpolations and an empty string will be inserted between them.
For example, the following code creates a template with empty placeholders
in the <a class="reference internal" href="#string.templatelib.Template.strings" title="string.templatelib.Template.strings"><code class="xref py py-attr docutils literal notranslate"><span class="pre">strings</span></code></a> attribute:</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span><span class="w"> </span><span class="nn">string.templatelib</span><span class="w"> </span><span class="kn">import</span> <span class="n">Interpolation</span><span class="p">,</span> <span class="n">Template</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span> <span class="o">=</span> <span class="n">Template</span><span class="p">(</span>
<span class="gp">... </span>    <span class="n">Interpolation</span><span class="p">(</span><span class="s1">&#39;Camembert&#39;</span><span class="p">,</span> <span class="s1">&#39;cheese&#39;</span><span class="p">),</span>
<span class="gp">... </span>    <span class="n">Interpolation</span><span class="p">(</span><span class="s1">&#39;.&#39;</span><span class="p">,</span> <span class="s1">&#39;punctuation&#39;</span><span class="p">),</span>
<span class="gp">... </span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span><span class="o">.</span><span class="n">strings</span>
<span class="go">(&#39;&#39;, &#39;&#39;, &#39;&#39;)</span>
</pre></div>
</div>
</dd></dl>

<dl class="describe">
<dt class="sig sig-object">
<span class="sig-name descname"><span class="pre">iter(template)</span></span></dt>
<dd><p>Iterate over the template, yielding each non-empty string and
<a class="reference internal" href="#string.templatelib.Interpolation" title="string.templatelib.Interpolation"><code class="xref py py-class docutils literal notranslate"><span class="pre">Interpolation</span></code></a> in the correct order:</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">cheese</span> <span class="o">=</span> <span class="s1">&#39;Camembert&#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="nb">list</span><span class="p">(</span><span class="sa">t</span><span class="s1">&#39;Ah! We do have </span><span class="si">{</span><span class="n">cheese</span><span class="si">}</span><span class="s1">.&#39;</span><span class="p">)</span>
<span class="go">[&#39;Ah! We do have &#39;, Interpolation(&#39;Camembert&#39;, &#39;cheese&#39;, None, &#39;&#39;), &#39;.&#39;]</span>
</pre></div>
</div>
<div class="admonition caution">
<p class="admonition-title">Caution</p>
<p>Empty strings are <strong>not</strong> included in the iteration:</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">response</span> <span class="o">=</span> <span class="s1">&#39;We do have &#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">cheese</span> <span class="o">=</span> <span class="s1">&#39;Camembert&#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="nb">list</span><span class="p">(</span><span class="sa">t</span><span class="s1">&#39;Ah! </span><span class="si">{</span><span class="n">response</span><span class="si">}{</span><span class="n">cheese</span><span class="si">}</span><span class="s1">.&#39;</span><span class="p">)</span>
<span class="go">[&#39;Ah! &#39;,</span>
<span class="go"> Interpolation(&#39;We do have &#39;, &#39;response&#39;, None, &#39;&#39;),</span>
<span class="go"> Interpolation(&#39;Camembert&#39;, &#39;cheese&#39;, None, &#39;&#39;),</span>
<span class="go"> &#39;.&#39;]</span>
</pre></div>
</div>
</div>
</dd></dl>

<dl class="describe">
<dt class="sig sig-object">
<span class="sig-name descname"><span class="pre">template</span> <span class="pre">+</span> <span class="pre">other</span></span></dt>
<dt class="sig sig-object">
<span class="sig-name descname"><span class="pre">template</span> <span class="pre">+=</span> <span class="pre">other</span></span></dt>
<dd><p>Concatenate this template with another, returning a new
<code class="xref py py-class docutils literal notranslate"><span class="pre">Template</span></code> instance:</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">cheese</span> <span class="o">=</span> <span class="s1">&#39;Camembert&#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="nb">list</span><span class="p">(</span><span class="sa">t</span><span class="s1">&#39;Ah! &#39;</span> <span class="o">+</span> <span class="sa">t</span><span class="s1">&#39;We do have </span><span class="si">{</span><span class="n">cheese</span><span class="si">}</span><span class="s1">.&#39;</span><span class="p">)</span>
<span class="go">[&#39;Ah! We do have &#39;, Interpolation(&#39;Camembert&#39;, &#39;cheese&#39;, None, &#39;&#39;), &#39;.&#39;]</span>
</pre></div>
</div>
<p>Concatenating a <code class="xref py py-class docutils literal notranslate"><span class="pre">Template</span></code> and a <code class="docutils literal notranslate"><span class="pre">str</span></code> is <strong>not</strong> supported.
This is because it is unclear whether the string should be treated as
a static string or an interpolation.
If you want to concatenate a <code class="xref py py-class docutils literal notranslate"><span class="pre">Template</span></code> with a string,
you should either wrap the string directly in a <code class="xref py py-class docutils literal notranslate"><span class="pre">Template</span></code>
(to treat it as a static string)
or use an <code class="xref py py-class docutils literal notranslate"><span class="pre">Interpolation</span></code> (to treat it as dynamic):</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span><span class="w"> </span><span class="nn">string.templatelib</span><span class="w"> </span><span class="kn">import</span> <span class="n">Interpolation</span><span class="p">,</span> <span class="n">Template</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span> <span class="o">=</span> <span class="sa">t</span><span class="s1">&#39;Ah! &#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="c1"># Treat &#39;We do have &#39; as a static string</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span> <span class="o">+=</span> <span class="n">Template</span><span class="p">(</span><span class="s1">&#39;We do have &#39;</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="c1"># Treat cheese as an interpolation</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">cheese</span> <span class="o">=</span> <span class="s1">&#39;Camembert&#39;</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">template</span> <span class="o">+=</span> <span class="n">Template</span><span class="p">(</span><span class="n">Interpolation</span><span class="p">(</span><span class="n">cheese</span><span class="p">,</span> <span class="s1">&#39;cheese&#39;</span><span class="p">))</span>
<span class="gp">&gt;&gt;&gt; </span><span class="nb">list</span><span class="p">(</span><span class="n">template</span><span class="p">)</span>
<span class="go">[&#39;Ah! We do have &#39;, Interpolation(&#39;Camembert&#39;, &#39;cheese&#39;, None, &#39;&#39;)]</span>
</pre></div>
</div>
</dd></dl>

</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="string.templatelib.Interpolation">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">string.templatelib.</span></span><span class="sig-name descname"><span class="pre">Interpolation</span></span><a class="headerlink" href="#string.templatelib.Interpolation" title="Link to this definition">¶</a></dt>
<dd><p>The <code class="xref py py-class docutils literal notranslate"><span class="pre">Interpolation</span></code> type represents an expression inside a template string.
It is immutable, meaning that attributes of an interpolation cannot be reassigned.</p>
<p>Interpolations support pattern matching, allowing you to match against
their attributes with the <a class="reference internal" href="../reference/compound_stmts.html#match"><span class="std std-ref">match statement</span></a>:</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span><span class="w"> </span><span class="nn">string.templatelib</span><span class="w"> </span><span class="kn">import</span> <span class="n">Interpolation</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">interpolation</span> <span class="o">=</span> <span class="sa">t</span><span class="s1">&#39;</span><span class="si">{</span><span class="mf">1.</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mf">2.</span><span class="si">:</span><span class="s1">.2f</span><span class="si">}</span><span class="s1">&#39;</span><span class="o">.</span><span class="n">interpolations</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">interpolation</span>
<span class="go">Interpolation(3.0, &#39;1. + 2.&#39;, None, &#39;.2f&#39;)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="k">match</span> <span class="n">interpolation</span><span class="p">:</span>
<span class="gp">... </span>    <span class="k">case</span> <span class="n">Interpolation</span><span class="p">(</span><span class="n">value</span><span class="p">,</span> <span class="n">expression</span><span class="p">,</span> <span class="n">conversion</span><span class="p">,</span> <span class="n">format_spec</span><span class="p">):</span>
<span class="gp">... </span>        <span class="nb">print</span><span class="p">(</span><span class="n">value</span><span class="p">,</span> <span class="n">expression</span><span class="p">,</span> <span class="n">conversion</span><span class="p">,</span> <span class="n">format_spec</span><span class="p">,</span> <span class="n">sep</span><span class="o">=</span><span class="s1">&#39; | &#39;</span><span class="p">)</span>
<span class="gp">...</span>
<span class="go">3.0 | 1. + 2. | None | .2f</span>
</pre></div>
</div>
<p class="rubric">Attributes</p>
<dl class="py attribute">
<dt class="sig sig-object py" id="string.templatelib.Interpolation.value">
<span class="sig-name descname"><span class="pre">value</span></span><em class="property"><span class="p"><span class="pre">:</span></span><span class="w"> </span><a class="reference internal" href="functions.html#object" title="object"><span class="pre">object</span></a></em><a class="headerlink" href="#string.templatelib.Interpolation.value" title="Link to this definition">¶</a></dt>
<dd><p>The evaluated value of the interpolation.</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="sa">t</span><span class="s1">&#39;</span><span class="si">{</span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">2</span><span class="si">}</span><span class="s1">&#39;</span><span class="o">.</span><span class="n">interpolations</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">value</span>
<span class="go">3</span>
</pre></div>
</div>
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="string.templatelib.Interpolation.expression">
<span class="sig-name descname"><span class="pre">expression</span></span><em class="property"><span class="p"><span class="pre">:</span></span><span class="w"> </span><a class="reference internal" href="stdtypes.html#str" title="str"><span class="pre">str</span></a></em><a class="headerlink" href="#string.templatelib.Interpolation.expression" title="Link to this definition">¶</a></dt>
<dd><p>For interpolations created by t-string literals, <code class="xref py py-attr docutils literal notranslate"><span class="pre">expression</span></code>
is the expression text found inside the curly brackets (<code class="docutils literal notranslate"><span class="pre">{</span></code> &amp; <code class="docutils literal notranslate"><span class="pre">}</span></code>),
including any whitespace, excluding the curly brackets themselves,
and ending before the first <code class="docutils literal notranslate"><span class="pre">!</span></code>, <code class="docutils literal notranslate"><span class="pre">:</span></code>, or <code class="docutils literal notranslate"><span class="pre">=</span></code> if any is present.
For manually created interpolations, <code class="xref py py-attr docutils literal notranslate"><span class="pre">expression</span></code> is the arbitrary
string provided when constructing the interpolation instance.</p>
<p>We recommend using valid Python expressions or the empty string for the
<code class="docutils literal notranslate"><span class="pre">expression</span></code> field of manually created <code class="xref py py-class docutils literal notranslate"><span class="pre">Interpolation</span></code>
instances, although this is not enforced at runtime.</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="sa">t</span><span class="s1">&#39;</span><span class="si">{</span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">2</span><span class="si">}</span><span class="s1">&#39;</span><span class="o">.</span><span class="n">interpolations</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">expression</span>
<span class="go">&#39;1 + 2&#39;</span>
</pre></div>
</div>
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="string.templatelib.Interpolation.conversion">
<span class="sig-name descname"><span class="pre">conversion</span></span><em class="property"><span class="p"><span class="pre">:</span></span><span class="w"> </span><a class="reference internal" href="typing.html#typing.Literal" title="typing.Literal"><span class="pre">Literal</span></a><span class="p"><span class="pre">[</span></span><span class="s"><span class="pre">'a'</span></span><span class="p"><span class="pre">,</span></span><span class="w"> </span><span class="s"><span class="pre">'r'</span></span><span class="p"><span class="pre">,</span></span><span class="w"> </span><span class="s"><span class="pre">'s'</span></span><span class="p"><span class="pre">]</span></span><span class="w"> </span><span class="p"><span class="pre">|</span></span><span class="w"> </span><a class="reference internal" href="constants.html#None" title="None"><span class="pre">None</span></a></em><a class="headerlink" href="#string.templatelib.Interpolation.conversion" title="Link to this definition">¶</a></dt>
<dd><p>The conversion to apply to the value, or <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p>
<p>The <code class="xref py py-attr docutils literal notranslate"><span class="pre">conversion</span></code> is the optional conversion to apply
to the value:</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="sa">t</span><span class="s1">&#39;</span><span class="si">{</span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">2</span><span class="si">!a}</span><span class="s1">&#39;</span><span class="o">.</span><span class="n">interpolations</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">conversion</span>
<span class="go">&#39;a&#39;</span>
</pre></div>
</div>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Unlike f-strings, where conversions are applied automatically,
the expected behavior with t-strings is that code that <em>processes</em> the
<code class="xref py py-class docutils literal notranslate"><span class="pre">Template</span></code> will decide how to interpret and whether to apply
the <code class="xref py py-attr docutils literal notranslate"><span class="pre">conversion</span></code>.
For convenience, the <a class="reference internal" href="#string.templatelib.convert" title="string.templatelib.convert"><code class="xref py py-func docutils literal notranslate"><span class="pre">convert()</span></code></a> function can be used to mimic
f-string conversion semantics.</p>
</div>
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="string.templatelib.Interpolation.format_spec">
<span class="sig-name descname"><span class="pre">format_spec</span></span><em class="property"><span class="p"><span class="pre">:</span></span><span class="w"> </span><a class="reference internal" href="stdtypes.html#str" title="str"><span class="pre">str</span></a></em><a class="headerlink" href="#string.templatelib.Interpolation.format_spec" title="Link to this definition">¶</a></dt>
<dd><p>The format specification to apply to the value.</p>
<p>The <code class="xref py py-attr docutils literal notranslate"><span class="pre">format_spec</span></code> is an optional, arbitrary string
used as the format specification to present the value:</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="sa">t</span><span class="s1">&#39;</span><span class="si">{</span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">2</span><span class="si">:</span><span class="s1">.2f</span><span class="si">}</span><span class="s1">&#39;</span><span class="o">.</span><span class="n">interpolations</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">format_spec</span>
<span class="go">&#39;.2f&#39;</span>
</pre></div>
</div>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Unlike f-strings, where format specifications are applied automatically
via the <a class="reference internal" href="functions.html#format" title="format"><code class="xref py py-func docutils literal notranslate"><span class="pre">format()</span></code></a> protocol, the expected behavior with
t-strings is that code that <em>processes</em> the interpolation will
decide how to interpret and whether to apply the format specification.
As a result, <code class="xref py py-attr docutils literal notranslate"><span class="pre">format_spec</span></code> values in interpolations
can be arbitrary strings,
including those that do not conform to the <code class="xref py py-func docutils literal notranslate"><span class="pre">format()</span></code> protocol.</p>
</div>
</dd></dl>

<p class="rubric">Methods</p>
<dl class="py method">
<dt class="sig sig-object py" id="string.templatelib.Interpolation.__new__">
<span class="sig-name descname"><span class="pre">__new__</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">value</span></span><span class="p"><span class="pre">:</span></span><span class="w"> </span><span class="n"><a class="reference internal" href="functions.html#object" title="object"><span class="pre">object</span></a></span></em>, <em class="sig-param"><span class="n"><span class="pre">expression</span></span><span class="p"><span class="pre">:</span></span><span class="w"> </span><span class="n"><a class="reference internal" href="stdtypes.html#str" title="str"><span class="pre">str</span></a></span></em>, <em class="sig-param"><span class="n"><span class="pre">conversion</span></span><span class="p"><span class="pre">:</span></span><span class="w"> </span><span class="n"><a class="reference internal" href="typing.html#typing.Literal" title="typing.Literal"><span class="pre">Literal</span></a><span class="p"><span class="pre">[</span></span><span class="s"><span class="pre">'a'</span></span><span class="p"><span class="pre">,</span></span><span class="w"> </span><span class="s"><span class="pre">'r'</span></span><span class="p"><span class="pre">,</span></span><span class="w"> </span><span class="s"><span class="pre">'s'</span></span><span class="p"><span class="pre">]</span></span><span class="w"> </span><span class="p"><span class="pre">|</span></span><span class="w"> </span><a class="reference internal" href="constants.html#None" title="None"><span class="pre">None</span></a></span><span class="w"> </span><span class="o"><span class="pre">=</span></span><span class="w"> </span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">format_spec</span></span><span class="p"><span class="pre">:</span></span><span class="w"> </span><span class="n"><a class="reference internal" href="stdtypes.html#str" title="str"><span class="pre">str</span></a></span><span class="w"> </span><span class="o"><span class="pre">=</span></span><span class="w"> </span><span class="default_value"><span class="pre">''</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#string.templatelib.Interpolation.__new__" title="Link to this definition">¶</a></dt>
<dd><p>Create a new <code class="xref py py-class docutils literal notranslate"><span class="pre">Interpolation</span></code> object from component parts.</p>
<dl class="field-list simple">
<dt class="field-odd">Parameters<span class="colon">:</span></dt>
<dd class="field-odd"><ul class="simple">
<li><p><strong>value</strong> – The evaluated, in-scope result of the interpolation.</p></li>
<li><p><strong>expression</strong> – The text of a valid Python expression,
or an empty string.</p></li>
<li><p><strong>conversion</strong> – The <a class="reference internal" href="string.html#formatstrings"><span class="std std-ref">conversion</span></a> to be used,
one of <code class="docutils literal notranslate"><span class="pre">None</span></code>, <code class="docutils literal notranslate"><span class="pre">'a'</span></code>, <code class="docutils literal notranslate"><span class="pre">'r'</span></code>, or <code class="docutils literal notranslate"><span class="pre">'s'</span></code>.</p></li>
<li><p><strong>format_spec</strong> – An optional, arbitrary string used as the
<a class="reference internal" href="string.html#formatspec"><span class="std std-ref">format specification</span></a> to present the value.</p></li>
</ul>
</dd>
</dl>
</dd></dl>

</dd></dl>

</section>
<section id="helper-functions">
<h2>Helper functions<a class="headerlink" href="#helper-functions" title="Link to this heading">¶</a></h2>
<dl class="py function">
<dt class="sig sig-object py" id="string.templatelib.convert">
<span class="sig-prename descclassname"><span class="pre">string.templatelib.</span></span><span class="sig-name descname"><span class="pre">convert</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">obj</span></span></em>, <em class="sig-param"><span class="positional-only-separator o"><abbr title="Positional-only parameter separator (PEP 570)"><span class="pre">/</span></abbr></span></em>, <em class="sig-param"><span class="n"><span class="pre">conversion</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#string.templatelib.convert" title="Link to this definition">¶</a></dt>
<dd><p>Applies formatted string literal <a class="reference internal" href="string.html#formatstrings-conversion"><span class="std std-ref">conversion</span></a>
semantics to the given object <em>obj</em>.
This is frequently useful for custom template string processing logic.</p>
<p>Three conversion flags are currently supported:</p>
<ul class="simple">
<li><p><code class="docutils literal notranslate"><span class="pre">'s'</span></code> which calls <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-func docutils literal notranslate"><span class="pre">str()</span></code></a> on the value (like <code class="docutils literal notranslate"><span class="pre">!s</span></code>),</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'r'</span></code> which calls <a class="reference internal" href="functions.html#repr" title="repr"><code class="xref py py-func docutils literal notranslate"><span class="pre">repr()</span></code></a> (like <code class="docutils literal notranslate"><span class="pre">!r</span></code>), and</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'a'</span></code> which calls <a class="reference internal" href="functions.html#ascii" title="ascii"><code class="xref py py-func docutils literal notranslate"><span class="pre">ascii()</span></code></a> (like <code class="docutils literal notranslate"><span class="pre">!a</span></code>).</p></li>
</ul>
<p>If the conversion flag is <code class="docutils literal notranslate"><span class="pre">None</span></code>, <em>obj</em> is returned unchanged.</p>
</dd></dl>

</section>
</section>


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