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<title>18.1.6.1 Emulation of compile()</title>
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<H3><A NAME="SECTION0020161000000000000000">
18.1.6.1 Emulation of <tt class="function">compile()</tt></A>
</H3>

<P>
While many useful operations may take place between parsing and
bytecode generation, the simplest operation is to do nothing.  For
this purpose, using the <tt class="module">parser</tt> module to produce an
intermediate data structure is equivalent to the code

<P>
<div class="verbatim"><pre>
&gt;&gt;&gt; code = compile('a + 5', 'file.py', 'eval')
&gt;&gt;&gt; a = 5
&gt;&gt;&gt; eval(code)
10
</pre></div>

<P>
The equivalent operation using the <tt class="module">parser</tt> module is somewhat
longer, and allows the intermediate internal parse tree to be retained
as an AST object:

<P>
<div class="verbatim"><pre>
&gt;&gt;&gt; import parser
&gt;&gt;&gt; ast = parser.expr('a + 5')
&gt;&gt;&gt; code = ast.compile('file.py')
&gt;&gt;&gt; a = 5
&gt;&gt;&gt; eval(code)
10
</pre></div>

<P>
An application which needs both AST and code objects can package this
code into readily available functions:

<P>
<div class="verbatim"><pre>
import parser

def load_suite(source_string):
    ast = parser.suite(source_string)
    return ast, ast.compile()

def load_expression(source_string):
    ast = parser.expr(source_string)
    return ast, ast.compile()
</pre></div>

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