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       <img src="" class="logo" alt=""><h1>Register compute bindings</h1>
       <small class="dont-index">Source: <a href="https://github.com/apache/arrow/blob/main/r/R/dplyr-funcs.R" class="external-link"><code>R/dplyr-funcs.R</code></a></small>
       <div class="d-none name"><code>register_binding.Rd</code></div>
     </div>

     <div class="ref-description section level2">
     <p>The <code>register_binding()</code> and <code>register_binding_agg()</code> functions
 are used to populate a list of functions that operate on (and return)
 Expressions. These are the basis for the <code>.data</code> mask inside dplyr methods.</p>
     </div>

     <div class="section level2">
     <h2 id="ref-usage">Usage<a class="anchor" aria-label="anchor" href="#ref-usage"></a></h2>
     <div class="sourceCode"><pre class="sourceCode r"><code><span><span class="fu">register_binding</span><span class="op">(</span></span>
 <span>  <span class="va">fun_name</span>,</span>
 <span>  <span class="va">fun</span>,</span>
 <span>  registry <span class="op">=</span> <span class="va">nse_funcs</span>,</span>
 <span>  update_cache <span class="op">=</span> <span class="cn">FALSE</span>,</span>
 <span>  notes <span class="op">=</span> <span class="fu"><a href="https://rdrr.io/r/base/character.html" class="external-link">character</a></span><span class="op">(</span><span class="fl">0</span><span class="op">)</span></span>
 <span><span class="op">)</span></span>
 <span></span>
 <span><span class="fu">register_binding_agg</span><span class="op">(</span></span>
 <span>  <span class="va">fun_name</span>,</span>
 <span>  <span class="va">agg_fun</span>,</span>
 <span>  registry <span class="op">=</span> <span class="va">agg_funcs</span>,</span>
 <span>  notes <span class="op">=</span> <span class="fu"><a href="https://rdrr.io/r/base/character.html" class="external-link">character</a></span><span class="op">(</span><span class="fl">0</span><span class="op">)</span></span>
 <span><span class="op">)</span></span></code></pre></div>
     </div>

     <div class="section level2">
     <h2 id="arguments">Arguments<a class="anchor" aria-label="anchor" href="#arguments"></a></h2>
     <dl><dt>fun_name</dt>
 <dd><p>A string containing a function name in the form <code>"function"</code> or
 <code>"package::function"</code>. The package name is currently not used but
 may be used in the future to allow these types of function calls.</p></dd>


 <dt>fun</dt>
 <dd><p>A function or <code>NULL</code> to un-register a previous function.
 This function must accept <code>Expression</code> objects as arguments and return
 <code>Expression</code> objects instead of regular R objects.</p></dd>


 <dt>registry</dt>
 <dd><p>An environment in which the functions should be
 assigned.</p></dd>


 <dt>update_cache</dt>
 <dd><p>Update .cache$functions at the time of registration.
 the default is FALSE because the majority of usage is to register
 bindings at package load, after which we create the cache once. The
 reason why .cache$functions is needed in addition to nse_funcs for
 non-aggregate functions could be revisited...it is currently used
 as the data mask in mutate, filter, and aggregate (but not
 summarise) because the data mask has to be a list.</p></dd>


 <dt>notes</dt>
 <dd><p>string for the docs: note any limitations or differences in
 behavior between the Arrow version and the R function.</p></dd>


 <dt>agg_fun</dt>
 <dd><p>An aggregate function or <code>NULL</code> to un-register a previous
 aggregate function. This function must accept <code>Expression</code> objects as
 arguments and return a <code><a href="https://rdrr.io/r/base/list.html" class="external-link">list()</a></code> with components:</p><ul><li><p><code>fun</code>: string function name</p></li>
 <li><p><code>data</code>: list of 0 or more <code>Expression</code>s</p></li>
 <li><p><code>options</code>: list of function options, as passed to call_function</p></li>
 </ul></dd>

 </dl></div>
     <div class="section level2">
     <h2 id="value">Value<a class="anchor" aria-label="anchor" href="#value"></a></h2>


 <p>The previously registered binding or <code>NULL</code> if no previously
 registered function existed.</p>
     </div>
     <div class="section level2">
     <h2 id="writing-bindings">Writing bindings<a class="anchor" aria-label="anchor" href="#writing-bindings"></a></h2>


 <ul><li><p><code>Expression$create()</code> will wrap any non-Expression inputs as Scalar
 Expressions. If you want to try to coerce scalar inputs to match the type
 of the Expression(s) in the arguments, call
 <code>cast_scalars_to_common_type(args)</code> on the
 args. For example, <code>Expression$create("add", args = list(int16_field, 1))</code>
 would result in a <code>float64</code> type output because <code>1</code> is a <code>double</code> in R.
 To prevent casting all of the data in <code>int16_field</code> to float and to
 preserve it as int16, do
 <code>Expression$create("add", args = cast_scalars_to_common_type(list(int16_field, 1)))</code></p></li>
 <li><p>Inside your function, you can call any other binding with <code>call_binding()</code>.</p></li>
 </ul></div>

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	<main id="main" class="col-md-9"><div class="page-header">
	<img src="" class="logo" alt=""><h1>Register compute bindings</h1>
	<small class="dont-index">Source: <a href="https://github.com/apache/arrow/blob/main/r/R/dplyr-funcs.R" class="external-link"><code>R/dplyr-funcs.R</code></a></small>
	<div class="d-none name"><code>register_binding.Rd</code></div>
	</div>

	<div class="ref-description section level2">
	<p>The <code>register_binding()</code> and <code>register_binding_agg()</code> functions
	are used to populate a list of functions that operate on (and return)
	Expressions. These are the basis for the <code>.data</code> mask inside dplyr methods.</p>
	</div>

	<div class="section level2">
	<h2 id="ref-usage">Usage<a class="anchor" aria-label="anchor" href="#ref-usage"></a></h2>
	<div class="sourceCode"><pre class="sourceCode r"><code><span><span class="fu">register_binding</span><span class="op">(</span></span>
	<span> <span class="va">fun_name</span>,</span>
	<span> <span class="va">fun</span>,</span>
	<span> registry <span class="op">=</span> <span class="va">nse_funcs</span>,</span>
	<span> update_cache <span class="op">=</span> <span class="cn">FALSE</span>,</span>
	<span> notes <span class="op">=</span> <span class="fu"><a href="https://rdrr.io/r/base/character.html" class="external-link">character</a></span><span class="op">(</span><span class="fl">0</span><span class="op">)</span></span>
	<span><span class="op">)</span></span>
	<span></span>
	<span><span class="fu">register_binding_agg</span><span class="op">(</span></span>
	<span> <span class="va">fun_name</span>,</span>
	<span> <span class="va">agg_fun</span>,</span>
	<span> registry <span class="op">=</span> <span class="va">agg_funcs</span>,</span>
	<span> notes <span class="op">=</span> <span class="fu"><a href="https://rdrr.io/r/base/character.html" class="external-link">character</a></span><span class="op">(</span><span class="fl">0</span><span class="op">)</span></span>
	<span><span class="op">)</span></span></code></pre></div>
	</div>

	<div class="section level2">
	<h2 id="arguments">Arguments<a class="anchor" aria-label="anchor" href="#arguments"></a></h2>
	<dl><dt>fun_name</dt>
	<dd><p>A string containing a function name in the form <code>"function"</code> or
	<code>"package::function"</code>. The package name is currently not used but
	may be used in the future to allow these types of function calls.</p></dd>


	<dt>fun</dt>
	<dd><p>A function or <code>NULL</code> to un-register a previous function.
	This function must accept <code>Expression</code> objects as arguments and return
	<code>Expression</code> objects instead of regular R objects.</p></dd>


	<dt>registry</dt>
	<dd><p>An environment in which the functions should be
	assigned.</p></dd>


	<dt>update_cache</dt>
	<dd><p>Update .cache$functions at the time of registration.
	the default is FALSE because the majority of usage is to register
	bindings at package load, after which we create the cache once. The
	reason why .cache$functions is needed in addition to nse_funcs for
	non-aggregate functions could be revisited...it is currently used
	as the data mask in mutate, filter, and aggregate (but not
	summarise) because the data mask has to be a list.</p></dd>


	<dt>notes</dt>
	<dd><p>string for the docs: note any limitations or differences in
	behavior between the Arrow version and the R function.</p></dd>


	<dt>agg_fun</dt>
	<dd><p>An aggregate function or <code>NULL</code> to un-register a previous
	aggregate function. This function must accept <code>Expression</code> objects as
	arguments and return a <code><a href="https://rdrr.io/r/base/list.html" class="external-link">list()</a></code> with components:</p><ul><li><p><code>fun</code>: string function name</p></li>
	<li><p><code>data</code>: list of 0 or more <code>Expression</code>s</p></li>
	<li><p><code>options</code>: list of function options, as passed to call_function</p></li>
	</ul></dd>

	</dl></div>
	<div class="section level2">
	<h2 id="value">Value<a class="anchor" aria-label="anchor" href="#value"></a></h2>


	<p>The previously registered binding or <code>NULL</code> if no previously
	registered function existed.</p>
	</div>
	<div class="section level2">
	<h2 id="writing-bindings">Writing bindings<a class="anchor" aria-label="anchor" href="#writing-bindings"></a></h2>


	<ul><li><p><code>Expression$create()</code> will wrap any non-Expression inputs as Scalar
	Expressions. If you want to try to coerce scalar inputs to match the type
	of the Expression(s) in the arguments, call
	<code>cast_scalars_to_common_type(args)</code> on the
	args. For example, <code>Expression$create("add", args = list(int16_field, 1))</code>
	would result in a <code>float64</code> type output because <code>1</code> is a <code>double</code> in R.
	To prevent casting all of the data in <code>int16_field</code> to float and to
	preserve it as int16, do
	<code>Expression$create("add", args = cast_scalars_to_common_type(list(int16_field, 1)))</code></p></li>
	<li><p>Inside your function, you can call any other binding with <code>call_binding()</code>.</p></li>
	</ul></div>

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