6 *************************
7 The Very High Level Layer
8 *************************
10 The functions in this chapter will let you execute Python source code given in a
11 file or a buffer, but they will not let you interact in a more detailed way with
14 Several of these functions accept a start symbol from the grammar as a
15 parameter. The available start symbols are :const:`Py_eval_input`,
16 :const:`Py_file_input`, and :const:`Py_single_input`. These are described
17 following the functions which accept them as parameters.
19 Note also that several of these functions take :ctype:`FILE\*` parameters. One
20 particular issue which needs to be handled carefully is that the :ctype:`FILE`
21 structure for different C libraries can be different and incompatible. Under
22 Windows (at least), it is possible for dynamically linked extensions to actually
23 use different libraries, so care should be taken that :ctype:`FILE\*` parameters
24 are only passed to these functions if it is certain that they were created by
25 the same library that the Python runtime is using.
28 .. cfunction:: int Py_Main(int argc, wchar_t **argv)
30 The main program for the standard interpreter. This is made
31 available for programs which embed Python. The *argc* and *argv*
32 parameters should be prepared exactly as those which are passed to
33 a C program's :cfunc:`main` function (converted to wchar_t
34 according to the user's locale). It is important to note that the
35 argument list may be modified (but the contents of the strings
36 pointed to by the argument list are not). The return value will be
37 the integer passed to the :func:`sys.exit` function, ``1`` if the
38 interpreter exits due to an exception, or ``2`` if the parameter
39 list does not represent a valid Python command line.
41 Note that if an otherwise unhandled :exc:`SystemError` is raised, this
42 function will not return ``1``, but exit the process, as long as
43 ``Py_InspectFlag`` is not set.
46 .. cfunction:: int PyRun_AnyFile(FILE *fp, const char *filename)
48 This is a simplified interface to :cfunc:`PyRun_AnyFileExFlags` below, leaving
49 *closeit* set to ``0`` and *flags* set to *NULL*.
52 .. cfunction:: int PyRun_AnyFileFlags(FILE *fp, const char *filename, PyCompilerFlags *flags)
54 This is a simplified interface to :cfunc:`PyRun_AnyFileExFlags` below, leaving
55 the *closeit* argument set to ``0``.
58 .. cfunction:: int PyRun_AnyFileEx(FILE *fp, const char *filename, int closeit)
60 This is a simplified interface to :cfunc:`PyRun_AnyFileExFlags` below, leaving
61 the *flags* argument set to *NULL*.
64 .. cfunction:: int PyRun_AnyFileExFlags(FILE *fp, const char *filename, int closeit, PyCompilerFlags *flags)
66 If *fp* refers to a file associated with an interactive device (console or
67 terminal input or Unix pseudo-terminal), return the value of
68 :cfunc:`PyRun_InteractiveLoop`, otherwise return the result of
69 :cfunc:`PyRun_SimpleFile`. If *filename* is *NULL*, this function uses
70 ``"???"`` as the filename.
73 .. cfunction:: int PyRun_SimpleString(const char *command)
75 This is a simplified interface to :cfunc:`PyRun_SimpleStringFlags` below,
76 leaving the *PyCompilerFlags\** argument set to NULL.
79 .. cfunction:: int PyRun_SimpleStringFlags(const char *command, PyCompilerFlags *flags)
81 Executes the Python source code from *command* in the :mod:`__main__` module
82 according to the *flags* argument. If :mod:`__main__` does not already exist, it
83 is created. Returns ``0`` on success or ``-1`` if an exception was raised. If
84 there was an error, there is no way to get the exception information. For the
85 meaning of *flags*, see below.
87 Note that if an otherwise unhandled :exc:`SystemError` is raised, this
88 function will not return ``-1``, but exit the process, as long as
89 ``Py_InspectFlag`` is not set.
92 .. cfunction:: int PyRun_SimpleFile(FILE *fp, const char *filename)
94 This is a simplified interface to :cfunc:`PyRun_SimpleFileExFlags` below,
95 leaving *closeit* set to ``0`` and *flags* set to *NULL*.
98 .. cfunction:: int PyRun_SimpleFileFlags(FILE *fp, const char *filename, PyCompilerFlags *flags)
100 This is a simplified interface to :cfunc:`PyRun_SimpleFileExFlags` below,
101 leaving *closeit* set to ``0``.
104 .. cfunction:: int PyRun_SimpleFileEx(FILE *fp, const char *filename, int closeit)
106 This is a simplified interface to :cfunc:`PyRun_SimpleFileExFlags` below,
107 leaving *flags* set to *NULL*.
110 .. cfunction:: int PyRun_SimpleFileExFlags(FILE *fp, const char *filename, int closeit, PyCompilerFlags *flags)
112 Similar to :cfunc:`PyRun_SimpleStringFlags`, but the Python source code is read
113 from *fp* instead of an in-memory string. *filename* should be the name of the
114 file. If *closeit* is true, the file is closed before PyRun_SimpleFileExFlags
118 .. cfunction:: int PyRun_InteractiveOne(FILE *fp, const char *filename)
120 This is a simplified interface to :cfunc:`PyRun_InteractiveOneFlags` below,
121 leaving *flags* set to *NULL*.
124 .. cfunction:: int PyRun_InteractiveOneFlags(FILE *fp, const char *filename, PyCompilerFlags *flags)
126 Read and execute a single statement from a file associated with an interactive
127 device according to the *flags* argument. If *filename* is *NULL*, ``"???"`` is
128 used instead. The user will be prompted using ``sys.ps1`` and ``sys.ps2``.
129 Returns ``0`` when the input was executed successfully, ``-1`` if there was an
130 exception, or an error code from the :file:`errcode.h` include file distributed
131 as part of Python if there was a parse error. (Note that :file:`errcode.h` is
132 not included by :file:`Python.h`, so must be included specifically if needed.)
135 .. cfunction:: int PyRun_InteractiveLoop(FILE *fp, const char *filename)
137 This is a simplified interface to :cfunc:`PyRun_InteractiveLoopFlags` below,
138 leaving *flags* set to *NULL*.
141 .. cfunction:: int PyRun_InteractiveLoopFlags(FILE *fp, const char *filename, PyCompilerFlags *flags)
143 Read and execute statements from a file associated with an interactive device
144 until EOF is reached. If *filename* is *NULL*, ``"???"`` is used instead. The
145 user will be prompted using ``sys.ps1`` and ``sys.ps2``. Returns ``0`` at EOF.
148 .. cfunction:: struct _node* PyParser_SimpleParseString(const char *str, int start)
150 This is a simplified interface to
151 :cfunc:`PyParser_SimpleParseStringFlagsFilename` below, leaving *filename* set
152 to *NULL* and *flags* set to ``0``.
155 .. cfunction:: struct _node* PyParser_SimpleParseStringFlags( const char *str, int start, int flags)
157 This is a simplified interface to
158 :cfunc:`PyParser_SimpleParseStringFlagsFilename` below, leaving *filename* set
162 .. cfunction:: struct _node* PyParser_SimpleParseStringFlagsFilename( const char *str, const char *filename, int start, int flags)
164 Parse Python source code from *str* using the start token *start* according to
165 the *flags* argument. The result can be used to create a code object which can
166 be evaluated efficiently. This is useful if a code fragment must be evaluated
170 .. cfunction:: struct _node* PyParser_SimpleParseFile(FILE *fp, const char *filename, int start)
172 This is a simplified interface to :cfunc:`PyParser_SimpleParseFileFlags` below,
173 leaving *flags* set to ``0``
176 .. cfunction:: struct _node* PyParser_SimpleParseFileFlags(FILE *fp, const char *filename, int start, int flags)
178 Similar to :cfunc:`PyParser_SimpleParseStringFlagsFilename`, but the Python
179 source code is read from *fp* instead of an in-memory string.
182 .. cfunction:: PyObject* PyRun_String(const char *str, int start, PyObject *globals, PyObject *locals)
184 This is a simplified interface to :cfunc:`PyRun_StringFlags` below, leaving
185 *flags* set to *NULL*.
188 .. cfunction:: PyObject* PyRun_StringFlags(const char *str, int start, PyObject *globals, PyObject *locals, PyCompilerFlags *flags)
190 Execute Python source code from *str* in the context specified by the
191 dictionaries *globals* and *locals* with the compiler flags specified by
192 *flags*. The parameter *start* specifies the start token that should be used to
193 parse the source code.
195 Returns the result of executing the code as a Python object, or *NULL* if an
196 exception was raised.
199 .. cfunction:: PyObject* PyRun_File(FILE *fp, const char *filename, int start, PyObject *globals, PyObject *locals)
201 This is a simplified interface to :cfunc:`PyRun_FileExFlags` below, leaving
202 *closeit* set to ``0`` and *flags* set to *NULL*.
205 .. cfunction:: PyObject* PyRun_FileEx(FILE *fp, const char *filename, int start, PyObject *globals, PyObject *locals, int closeit)
207 This is a simplified interface to :cfunc:`PyRun_FileExFlags` below, leaving
208 *flags* set to *NULL*.
211 .. cfunction:: PyObject* PyRun_FileFlags(FILE *fp, const char *filename, int start, PyObject *globals, PyObject *locals, PyCompilerFlags *flags)
213 This is a simplified interface to :cfunc:`PyRun_FileExFlags` below, leaving
214 *closeit* set to ``0``.
217 .. cfunction:: PyObject* PyRun_FileExFlags(FILE *fp, const char *filename, int start, PyObject *globals, PyObject *locals, int closeit, PyCompilerFlags *flags)
219 Similar to :cfunc:`PyRun_StringFlags`, but the Python source code is read from
220 *fp* instead of an in-memory string. *filename* should be the name of the file.
221 If *closeit* is true, the file is closed before :cfunc:`PyRun_FileExFlags`
225 .. cfunction:: PyObject* Py_CompileString(const char *str, const char *filename, int start)
227 This is a simplified interface to :cfunc:`Py_CompileStringFlags` below, leaving
228 *flags* set to *NULL*.
231 .. cfunction:: PyObject* Py_CompileStringFlags(const char *str, const char *filename, int start, PyCompilerFlags *flags)
233 Parse and compile the Python source code in *str*, returning the resulting code
234 object. The start token is given by *start*; this can be used to constrain the
235 code which can be compiled and should be :const:`Py_eval_input`,
236 :const:`Py_file_input`, or :const:`Py_single_input`. The filename specified by
237 *filename* is used to construct the code object and may appear in tracebacks or
238 :exc:`SyntaxError` exception messages. This returns *NULL* if the code cannot
239 be parsed or compiled.
242 .. cfunction:: PyObject* PyEval_EvalCode(PyCodeObject *co, PyObject *globals, PyObject *locals)
244 This is a simplified interface to :cfunc:`PyEval_EvalCodeEx`, with just
245 the code object, and the dictionaries of global and local variables.
246 The other arguments are set to *NULL*.
249 .. cfunction:: PyObject* PyEval_EvalCodeEx(PyCodeObject *co, PyObject *globals, PyObject *locals, PyObject **args, int argcount, PyObject **kws, int kwcount, PyObject **defs, int defcount, PyObject *closure)
251 Evaluate a precompiled code object, given a particular environment for its
252 evaluation. This environment consists of dictionaries of global and local
253 variables, arrays of arguments, keywords and defaults, and a closure tuple of
257 .. cfunction:: PyObject* PyEval_EvalFrame(PyFrameObject *f)
259 Evaluate an execution frame. This is a simplified interface to
260 PyEval_EvalFrameEx, for backward compatibility.
263 .. cfunction:: PyObject* PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
265 This is the main, unvarnished function of Python interpretation. It is
266 literally 2000 lines long. The code object associated with the execution
267 frame *f* is executed, interpreting bytecode and executing calls as needed.
268 The additional *throwflag* parameter can mostly be ignored - if true, then
269 it causes an exception to immediately be thrown; this is used for the
270 :meth:`throw` methods of generator objects.
273 .. cfunction:: int PyEval_MergeCompilerFlags(PyCompilerFlags *cf)
275 This function changes the flags of the current evaluation frame, and returns
276 true on success, false on failure.
279 .. cvar:: int Py_eval_input
281 .. index:: single: Py_CompileString()
283 The start symbol from the Python grammar for isolated expressions; for use with
284 :cfunc:`Py_CompileString`.
287 .. cvar:: int Py_file_input
289 .. index:: single: Py_CompileString()
291 The start symbol from the Python grammar for sequences of statements as read
292 from a file or other source; for use with :cfunc:`Py_CompileString`. This is
293 the symbol to use when compiling arbitrarily long Python source code.
296 .. cvar:: int Py_single_input
298 .. index:: single: Py_CompileString()
300 The start symbol from the Python grammar for a single statement; for use with
301 :cfunc:`Py_CompileString`. This is the symbol used for the interactive
305 .. ctype:: struct PyCompilerFlags
307 This is the structure used to hold compiler flags. In cases where code is only
308 being compiled, it is passed as ``int flags``, and in cases where code is being
309 executed, it is passed as ``PyCompilerFlags *flags``. In this case, ``from
310 __future__ import`` can modify *flags*.
312 Whenever ``PyCompilerFlags *flags`` is *NULL*, :attr:`cf_flags` is treated as
313 equal to ``0``, and any modification due to ``from __future__ import`` is
316 struct PyCompilerFlags {
321 .. cvar:: int CO_FUTURE_DIVISION
323 This bit can be set in *flags* to cause division operator ``/`` to be
324 interpreted as "true division" according to :pep:`238`.