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<H2><A NAME="SECTION0021320000000000000000">
19.3.2 Assignment nodes</A>
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<P>
There is a collection of nodes used to represent assignments.  Each
assignment statement in the source code becomes a single
<tt class="class">Assign</tt> node in the AST.  The <tt class="member">nodes</tt> attribute is a
list that contains a node for each assignment target.  This is
necessary because assignment can be chained, e.g. <code>a = b = 2</code>.
Each <tt class="class">Node</tt> in the list will be one of the following classes:
<tt class="class">AssAttr</tt>, <tt class="class">AssList</tt>, <tt class="class">AssName</tt>, or
<tt class="class">AssTuple</tt>.

<P>
Each target assignment node will describe the kind of object being
assigned to:  <tt class="class">AssName</tt> for a simple name, e.g. <code>a = 1</code>.
<tt class="class">AssAttr</tt> for an attribute assigned, e.g. <code>a.x = 1</code>.
<tt class="class">AssList</tt> and <tt class="class">AssTuple</tt> for list and tuple expansion
respectively, e.g. <code>a, b, c = a_tuple</code>.

<P>
The target assignment nodes also have a <tt class="member">flags</tt> attribute that
indicates whether the node is being used for assignment or in a delete
statement.  The <tt class="class">AssName</tt> is also used to represent a delete
statement, e.g. <tt class="class">del x</tt>.

<P>
When an expression contains several attribute references, an
assignment or delete statement will contain only one <tt class="class">AssAttr</tt>
node - for the final attribute reference.  The other attribute
references will be represented as <tt class="class">Getattr</tt> nodes in the
<tt class="member">expr</tt> attribute of the <tt class="class">AssAttr</tt> instance.

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<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
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