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authorGeorg Brandl <georg@python.org>2007-08-15 14:28:22 (GMT)
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+
+:mod:`codeop` --- Compile Python code
+=====================================
+
+.. module:: codeop
+ :synopsis: Compile (possibly incomplete) Python code.
+.. sectionauthor:: Moshe Zadka <moshez@zadka.site.co.il>
+.. sectionauthor:: Michael Hudson <mwh@python.net>
+
+
+.. % LaTeXed from excellent doc-string.
+
+The :mod:`codeop` module provides utilities upon which the Python
+read-eval-print loop can be emulated, as is done in the :mod:`code` module. As
+a result, you probably don't want to use the module directly; if you want to
+include such a loop in your program you probably want to use the :mod:`code`
+module instead.
+
+There are two parts to this job:
+
+#. Being able to tell if a line of input completes a Python statement: in
+ short, telling whether to print '``>>>``' or '``...``' next.
+
+#. Remembering which future statements the user has entered, so subsequent
+ input can be compiled with these in effect.
+
+The :mod:`codeop` module provides a way of doing each of these things, and a way
+of doing them both.
+
+To do just the former:
+
+
+.. function:: compile_command(source[, filename[, symbol]])
+
+ Tries to compile *source*, which should be a string of Python code and return a
+ code object if *source* is valid Python code. In that case, the filename
+ attribute of the code object will be *filename*, which defaults to
+ ``'<input>'``. Returns ``None`` if *source* is *not* valid Python code, but is a
+ prefix of valid Python code.
+
+ If there is a problem with *source*, an exception will be raised.
+ :exc:`SyntaxError` is raised if there is invalid Python syntax, and
+ :exc:`OverflowError` or :exc:`ValueError` if there is an invalid literal.
+
+ The *symbol* argument determines whether *source* is compiled as a statement
+ (``'single'``, the default) or as an expression (``'eval'``). Any other value
+ will cause :exc:`ValueError` to be raised.
+
+ **Caveat:** It is possible (but not likely) that the parser stops parsing with a
+ successful outcome before reaching the end of the source; in this case, trailing
+ symbols may be ignored instead of causing an error. For example, a backslash
+ followed by two newlines may be followed by arbitrary garbage. This will be
+ fixed once the API for the parser is better.
+
+
+.. class:: Compile()
+
+ Instances of this class have :meth:`__call__` methods identical in signature to
+ the built-in function :func:`compile`, but with the difference that if the
+ instance compiles program text containing a :mod:`__future__` statement, the
+ instance 'remembers' and compiles all subsequent program texts with the
+ statement in force.
+
+
+.. class:: CommandCompiler()
+
+ Instances of this class have :meth:`__call__` methods identical in signature to
+ :func:`compile_command`; the difference is that if the instance compiles program
+ text containing a ``__future__`` statement, the instance 'remembers' and
+ compiles all subsequent program texts with the statement in force.
+
+A note on version compatibility: the :class:`Compile` and
+:class:`CommandCompiler` are new in Python 2.2. If you want to enable the
+future-tracking features of 2.2 but also retain compatibility with 2.1 and
+earlier versions of Python you can either write ::
+
+ try:
+ from codeop import CommandCompiler
+ compile_command = CommandCompiler()
+ del CommandCompiler
+ except ImportError:
+ from codeop import compile_command
+
+which is a low-impact change, but introduces possibly unwanted global state into
+your program, or you can write::
+
+ try:
+ from codeop import CommandCompiler
+ except ImportError:
+ def CommandCompiler():
+ from codeop import compile_command
+ return compile_command
+
+and then call ``CommandCompiler`` every time you need a fresh compiler object.
+