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<head><title>newClass -- set the class and parent of an object</title>
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<div><a href="index.html" title="">Macaulay2Doc</a> > <a href="___The_sp__Macaulay2_splanguage.html" title="">The Macaulay2 language</a> > <a href="_new.html" title="new objects and new types">new</a> > <a href="_new__Class.html" title="set the class and parent of an object">newClass</a></div>
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<div><h1>newClass -- set the class and parent of an object</h1>
<div class="single"><h2>Description</h2>
<div><div><h2>setting the class and parent</h2>
<ul><li><div class="list"><dl class="element"><dt class="heading">Usage: </dt><dd class="value"><div><tt>newClass(A,B,x)</tt></div>
</dd></dl>
</div>
</li>
<li>Inputs:<ul><li><span><tt>A</tt>, <span>a <a href="___Hash__Table.html">hash table</a></span></span></li>
<li><span><tt>B</tt>, <span>a <a href="___Hash__Table.html">hash table</a></span></span></li>
<li><span><tt>x</tt></span></li>
</ul>
</li>
<li>Outputs:<ul><li><span>a copy (possibly) of <tt>x</tt> with <tt>A</tt> as class and <tt>B</tt> as parent</span></li>
</ul>
</li>
</ul>
</div>
<div><h2>setting the class</h2>
<ul><li><div class="list"><dl class="element"><dt class="heading">Usage: </dt><dd class="value"><div><tt>newClass(A,x)</tt></div>
</dd></dl>
</div>
</li>
<li>Inputs:<ul><li><span><tt>A</tt>, <span>a <a href="___Hash__Table.html">hash table</a></span></span></li>
<li><span><tt>x</tt></span></li>
</ul>
</li>
<li>Outputs:<ul><li><span>a copy (possibly) of <tt>x</tt> with <tt>A</tt> as the new class</span></li>
</ul>
</li>
</ul>
</div>
<h2>common remarks</h2>
<p>If <tt>x</tt> is a basic list or sequence, then <a href="___Basic__List.html" title="the class of all basic lists">BasicList</a> should be an ancestor of <tt>A</tt> and <tt>B</tt> should be <a href="___Nothing.html" title="the empty class">Nothing</a>. If <tt>x</tt> is a hash table, then <a href="___Hash__Table.html" title="the class of all hash tables">HashTable</a> should be an ancestor of <tt>A</tt>.</p>
<p>If the class (and parent) of x are already equal to A (and B, respectively), then copying of the elements of <tt>x</tt> is not required, and is not done.</p>
<p>If <tt>x</tt> is mutable, and instances of class <tt>A</tt> are also mutable, then copying of the elements of <tt>x</tt> is not required, and is not done.</p>
<p>If <tt>x</tt> is not a hash table, basic list, or sequence, then its class will be set to <tt>A</tt> internally, essentially by wrapping it in a special kind of object designed solely to indicate the new class. The new class <tt>A</tt> must be a specialization of the class of <tt>x</tt>. The parent cannot be reset this way. Not all of the internal code of Macaulay2 is ready to recognize such wrapped objects, which are part of a new feature, except for the code that handles functions.</p>
<table class="examples"><tr><td><pre>i1 : t = 1..4
o1 = (1, 2, 3, 4)
o1 : Sequence</pre>
</td></tr>
<tr><td><pre>i2 : newClass(Array,t)
o2 = [1, 2, 3, 4]
o2 : Array</pre>
</td></tr>
<tr><td><pre>i3 : x = new HashTable from { a => 1, b => 2 }
o3 = HashTable{a => 1}
b => 2
o3 : HashTable</pre>
</td></tr>
<tr><td><pre>i4 : z = newClass(ImmutableType,Vector,x)
o4 = ImmutableType{a => 1}
b => 2
o4 : ImmutableType</pre>
</td></tr>
<tr><td><pre>i5 : parent z
o5 = Vector
o5 : Type</pre>
</td></tr>
</table>
<p>The difference between <tt>new A of B from x</tt> and <tt>newClass(A,B,x)</tt> is that the methods installed for <a href="_new.html" title="new objects and new types">new</a> are not used.</p>
<table class="examples"><tr><td><pre>i6 : new Thing of Thing from Thing := (A,B,c) -> (
<< "-- new " << A << " of " << B
<< " from " << toString c << endl;
c);</pre>
</td></tr>
<tr><td><pre>i7 : new ImmutableType of Vector from x
-- new ImmutableType of Vector from new HashTable from {a => 1, b => 2}
o7 = ImmutableType{a => 1}
b => 2
o7 : ImmutableType</pre>
</td></tr>
<tr><td><pre>i8 : newClass(ImmutableType,Vector,x)
o8 = ImmutableType{a => 1}
b => 2
o8 : ImmutableType</pre>
</td></tr>
</table>
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<div class="single"><h2>See also</h2>
<ul><li><span><a href="_new.html" title="new objects and new types">new</a> -- new objects and new types</span></li>
<li><span><a href="_copy.html" title="copy an object">copy</a> -- copy an object</span></li>
<li><span><a href="_to__List.html" title="list of elements">toList</a> -- list of elements</span></li>
</ul>
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