Binding properties pattern

<h2 id="comparison-with-aspect-oriented-implementation">Comparison with aspect-oriented implementation</h2>
As an alternative to the aspect-oriented implementation of mutual properties, property binding can be proposed. In LibPropC++ <a href="/facts/C%2B%2B/Et0F2qn9">C++</a> library it is implemented too.<a class="footnote-ref" id="fnref:3" href="#fn:3">3</a>
Some weakness in the LibPropC++ (with property binding):

<ol><li>Its use is not transparent as it requires to be declared necessary object attributes as properties and appropriate accessor methods must be provided</li>
<li>Binding of attributes in LibPropC++ is not designed to replace method calls</li>
<li>The library does not maintain an interaction history.<a class="footnote-ref" id="fnref:4" href="#fn:4">4</a></li></ol>
<h2 id="implementation">Implementation</h2>
There are two types of binding. One-way binding should be applied when one of the properties is read-only. In other cases, two-way binding must be applied.<a class="footnote-ref" id="fnref:5" href="#fn:5">5</a><a class="footnote-ref" id="fnref:6" href="#fn:6">6</a>
Infinite loops can be eliminated by blocking the signal, or comparing the assigned value with the property value before assignment, or eliminating unnecessary assignments.<a class="footnote-ref" id="fnref:7" href="#fn:7">7</a><a class="footnote-ref" id="fnref:8" href="#fn:8">8</a>
Binding properties of different types can be achieved through <a href="/facts/Type_conversion/FuPD945T">type conversions</a>.<a class="footnote-ref" id="fnref:9" href="#fn:9">9</a><a class="footnote-ref" id="fnref:10" href="#fn:10">10</a>
Binding properties with transformations can be achieved through reducing the transformation function to the problem of binding properties, and the function can be imaginary consider as Type Conversions.<a class="footnote-ref" id="fnref:11" href="#fn:11">11</a><a class="footnote-ref" id="fnref:12" href="#fn:12">12</a>

<a href="/facts/Procedural_programming/7r5xz7kx">Procedural programming</a>
 <a href="/facts/Object-oriented_programming/TxNMEcao">Object-oriented programming</a>
 Signals/event programming
 Components with properties
 binding properties together<a class="footnote-ref" id="fnref:13" href="#fn:13">13</a>
<h2 id="resulting-context">Resulting context</h2>
Properties are being kept synchronized automatically. Between library calls they always have the values expressed by the EqualityConstraints.<a class="footnote-ref" id="fnref:14" href="#fn:14">14</a>

<h2 id="deficiencies">Deficiencies</h2>
Property changes watching mechanism acquires some resources.<a class="footnote-ref" id="fnref:15" href="#fn:15">15</a>

<h2 id="sample-code">Sample code</h2>
Code sketch for one-way binding may look like as follows:

bind_multiple_one_way(src_obj, src_prop, dst_objs[], dst_props[])
{
 for (i, j) in (dst_objs, dst_props)
 {
 bind_properties_one_way(src_obj, src_prop, i, j);
 }
}
<a class="footnote-ref" id="fnref:16" href="#fn:16">16</a>
Two-way binding can be expressed as follows (in <a href="/facts/C%2B%2B/Et0F2qn9">C++</a>):

// In this pseudo-code are not taken into the account initial values assignments
bind_two_way(prop1, prop2)
{
 bind(prop1, prop2);
 bind(prop2, prop1);
}
<a class="footnote-ref" id="fnref:17" href="#fn:17">17</a>
Accomplishing the binding (i.e. connecting the property change notification in an event handler) may be like as follows:

on_property_change(src_prop, dst_prop)
{
 block_signal(src_obj, on_property_change);
 dst_prop := src_prop;
 unblock_signal(src_obj, on_property_change);
}
<a class="footnote-ref" id="fnref:18" href="#fn:18">18</a>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Software_design_pattern/mV7r4egw">Software design pattern</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1">"Binding Properties". Cunningham & Cunningham. Cunningham & Cunningham. Retrieved 4 February 2015. <a href="http://c2.com/cgi/wiki?BindingProperties" target="_blank">http://c2.com/cgi/wiki?BindingProperties</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></li>
<li id="fn:2">Porton, V. "Binding together Properties of Objects". Victor Porton. Retrieved 25 February 2021. <a href="https://cloudflare-ipfs.com/ipfs/QmNj5xHJx9JEWfPAttTTitXnjFKwm319nLZU8BfAoMwx9h/" target="_blank">https://cloudflare-ipfs.com/ipfs/QmNj5xHJx9JEWfPAttTTitXnjFKwm319nLZU8BfAoMwx9h/</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></li>
<li id="fn:3">Evermann, J., The Association Construct in Conceptual Modelling - An Analysis Using the Bunge Ontological Model, Wellington, New Zealand: School of Information Management, Victoria University <a href="#fnref:3" class="footnote-back-ref">↩</a></li>
<li id="fn:4">Evermann, J., The Association Construct in Conceptual Modelling - An Analysis Using the Bunge Ontological Model, Wellington, New Zealand: School of Information Management, Victoria University <a href="#fnref:4" class="footnote-back-ref">↩</a></li>
<li id="fn:5">Porton, V. "Binding together Properties of Objects". Victor Porton. Retrieved 25 February 2021. <a href="https://cloudflare-ipfs.com/ipfs/QmNj5xHJx9JEWfPAttTTitXnjFKwm319nLZU8BfAoMwx9h/" target="_blank">https://cloudflare-ipfs.com/ipfs/QmNj5xHJx9JEWfPAttTTitXnjFKwm319nLZU8BfAoMwx9h/</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></li>
<li id="fn:6">Evermann, J., The Association Construct in Conceptual Modelling - An Analysis Using the Bunge Ontological Model, Wellington, New Zealand: School of Information Management, Victoria University <a href="#fnref:6" class="footnote-back-ref">↩</a></li>
<li id="fn:7">Porton, V. "Binding together Properties of Objects". Victor Porton. Retrieved 25 February 2021. <a href="https://cloudflare-ipfs.com/ipfs/QmNj5xHJx9JEWfPAttTTitXnjFKwm319nLZU8BfAoMwx9h/" target="_blank">https://cloudflare-ipfs.com/ipfs/QmNj5xHJx9JEWfPAttTTitXnjFKwm319nLZU8BfAoMwx9h/</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></li>
<li id="fn:8">Evermann, J., The Association Construct in Conceptual Modelling - An Analysis Using the Bunge Ontological Model, Wellington, New Zealand: School of Information Management, Victoria University <a href="#fnref:8" class="footnote-back-ref">↩</a></li>
<li id="fn:9">Porton, V. "Binding together Properties of Objects". Victor Porton. Retrieved 25 February 2021. <a href="https://cloudflare-ipfs.com/ipfs/QmNj5xHJx9JEWfPAttTTitXnjFKwm319nLZU8BfAoMwx9h/" target="_blank">https://cloudflare-ipfs.com/ipfs/QmNj5xHJx9JEWfPAttTTitXnjFKwm319nLZU8BfAoMwx9h/</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></li>
<li id="fn:10">Evermann, J., The Association Construct in Conceptual Modelling - An Analysis Using the Bunge Ontological Model, Wellington, New Zealand: School of Information Management, Victoria University <a href="#fnref:10" class="footnote-back-ref">↩</a></li>
<li id="fn:11">Porton, V. "Binding together Properties of Objects". Victor Porton. Retrieved 25 February 2021. <a href="https://cloudflare-ipfs.com/ipfs/QmNj5xHJx9JEWfPAttTTitXnjFKwm319nLZU8BfAoMwx9h/" target="_blank">https://cloudflare-ipfs.com/ipfs/QmNj5xHJx9JEWfPAttTTitXnjFKwm319nLZU8BfAoMwx9h/</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></li>
<li id="fn:12">Evermann, J., The Association Construct in Conceptual Modelling - An Analysis Using the Bunge Ontological Model, Wellington, New Zealand: School of Information Management, Victoria University <a href="#fnref:12" class="footnote-back-ref">↩</a></li>
<li id="fn:13">Porton, V. "Binding together Properties of Objects". Victor Porton. Retrieved 25 February 2021. <a href="https://cloudflare-ipfs.com/ipfs/QmNj5xHJx9JEWfPAttTTitXnjFKwm319nLZU8BfAoMwx9h/" target="_blank">https://cloudflare-ipfs.com/ipfs/QmNj5xHJx9JEWfPAttTTitXnjFKwm319nLZU8BfAoMwx9h/</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></li>
<li id="fn:14">Evermann, J., The Association Construct in Conceptual Modelling - An Analysis Using the Bunge Ontological Model, Wellington, New Zealand: School of Information Management, Victoria University <a href="#fnref:14" class="footnote-back-ref">↩</a></li>
<li id="fn:15">Evermann, J., The Association Construct in Conceptual Modelling - An Analysis Using the Bunge Ontological Model, Wellington, New Zealand: School of Information Management, Victoria University <a href="#fnref:15" class="footnote-back-ref">↩</a></li>
<li id="fn:16">Porton, V. "Binding together Properties of Objects". Victor Porton. Retrieved 25 February 2021. <a href="https://cloudflare-ipfs.com/ipfs/QmNj5xHJx9JEWfPAttTTitXnjFKwm319nLZU8BfAoMwx9h/" target="_blank">https://cloudflare-ipfs.com/ipfs/QmNj5xHJx9JEWfPAttTTitXnjFKwm319nLZU8BfAoMwx9h/</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></li>
<li id="fn:17">Evermann, J., The Association Construct in Conceptual Modelling - An Analysis Using the Bunge Ontological Model, Wellington, New Zealand: School of Information Management, Victoria University <a href="#fnref:17" class="footnote-back-ref">↩</a></li>
<li id="fn:18">Evermann, J., The Association Construct in Conceptual Modelling - An Analysis Using the Bunge Ontological Model, Wellington, New Zealand: School of Information Management, Victoria University <a href="#fnref:18" class="footnote-back-ref">↩</a></li>
</ol>

Binding properties pattern open-in-new

Binding properties pattern