Repository navigation
Expand file tree
/
Copy pathveryhigh.rst
More file actions
582 lines (377 loc) · 22.7 KB
/
Copy pathveryhigh.rst
File metadata and controls
582 lines (377 loc) · 22.7 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
.. highlight:: c
.. _veryhigh:
*************************
The Very High Level Layer
*************************
The functions in this chapter will let you execute Python source code given in a
file or a buffer, but they will not let you interact in a more detailed way with
the interpreter.
Several of these functions accept a start symbol from the grammar as a
parameter. The available start symbols are :c:data:`Py_eval_input`,
:c:data:`Py_file_input`, :c:data:`Py_single_input`, and
:c:data:`Py_func_type_input`. These are described following the functions
which accept them as parameters.
Note also that several of these functions take :c:expr:`FILE*` parameters. One
particular issue which needs to be handled carefully is that the :c:type:`FILE`
structure for different C libraries can be different and incompatible. Under
Windows (at least), it is possible for dynamically linked extensions to actually
use different libraries, so care should be taken that :c:expr:`FILE*` parameters
are only passed to these functions if it is certain that they were created by
the same library that the Python runtime is using.
.. c:function:: int PyRun_AnyFile(FILE *fp, const char *filename)
This is a simplified interface to :c:func:`PyRun_AnyFileExFlags` below, leaving
*closeit* set to ``0`` and *flags* set to ``NULL``.
.. c:function:: int PyRun_AnyFileFlags(FILE *fp, const char *filename, PyCompilerFlags *flags)
This is a simplified interface to :c:func:`PyRun_AnyFileExFlags` below, leaving
the *closeit* argument set to ``0``.
.. c:function:: int PyRun_AnyFileEx(FILE *fp, const char *filename, int closeit)
This is a simplified interface to :c:func:`PyRun_AnyFileExFlags` below, leaving
the *flags* argument set to ``NULL``.
.. c:function:: int PyRun_AnyFileExFlags(FILE *fp, const char *filename, int closeit, PyCompilerFlags *flags)
If *fp* refers to a file associated with an interactive device (console or
terminal input or Unix pseudo-terminal), return the value of
:c:func:`PyRun_InteractiveLoop`, otherwise return the result of
:c:func:`PyRun_SimpleFile`. *filename* is decoded from the filesystem
encoding (:func:`sys.getfilesystemencoding`). If *filename* is ``NULL``, this
function uses ``"???"`` as the filename.
If *closeit* is true, the file is closed before
``PyRun_SimpleFileExFlags()`` returns.
.. c:function:: int PyRun_SimpleString(const char *command)
This is a simplified interface to :c:func:`PyRun_SimpleStringFlags` below,
leaving the :c:struct:`PyCompilerFlags`\* argument set to ``NULL``.
.. c:function:: int PyRun_SimpleStringFlags(const char *command, PyCompilerFlags *flags)
Executes the Python source code from *command* in the :mod:`__main__` module
according to the *flags* argument. If :mod:`__main__` does not already exist, it
is created. Returns ``0`` on success or ``-1`` if an exception was raised. If
there was an error, there is no way to get the exception information. For the
meaning of *flags*, see below.
Note that if an otherwise unhandled :exc:`SystemExit` is raised, this
function will not return ``-1``, but exit the process, as long as
:c:member:`PyConfig.inspect` is zero.
.. c:function:: int PyRun_SimpleFile(FILE *fp, const char *filename)
This is a simplified interface to :c:func:`PyRun_SimpleFileExFlags` below,
leaving *closeit* set to ``0`` and *flags* set to ``NULL``.
.. c:function:: int PyRun_SimpleFileEx(FILE *fp, const char *filename, int closeit)
This is a simplified interface to :c:func:`PyRun_SimpleFileExFlags` below,
leaving *flags* set to ``NULL``.
.. c:function:: int PyRun_SimpleFileExFlags(FILE *fp, const char *filename, int closeit, PyCompilerFlags *flags)
Similar to :c:func:`PyRun_SimpleStringFlags`, but the Python source code is read
from *fp* instead of an in-memory string. *filename* should be the name of
the file, it is decoded from :term:`filesystem encoding and error handler`.
If *closeit* is true, the file is closed before
``PyRun_SimpleFileExFlags()`` returns.
.. note::
On Windows, *fp* should be opened as binary mode (e.g. ``fopen(filename, "rb")``).
Otherwise, Python may not handle script file with LF line ending correctly.
.. c:function:: int PyRun_InteractiveOneObject(FILE *fp, PyObject *filename, PyCompilerFlags *flags)
Read and execute a single statement from a file associated with an
interactive device according to the *flags* argument. The user will be
prompted using ``sys.ps1`` and ``sys.ps2``. *filename* must be a Python
:class:`str` object.
Returns ``0`` when the input was
executed successfully, ``-1`` if there was an exception, or an error code
from the :file:`errcode.h` include file distributed as part of Python if
there was a parse error. (Note that :file:`errcode.h` is not included by
:file:`Python.h`, so must be included specifically if needed.)
.. c:function:: int PyRun_InteractiveOne(FILE *fp, const char *filename)
This is a simplified interface to :c:func:`PyRun_InteractiveOneFlags` below,
leaving *flags* set to ``NULL``.
.. c:function:: int PyRun_InteractiveOneFlags(FILE *fp, const char *filename, PyCompilerFlags *flags)
Similar to :c:func:`PyRun_InteractiveOneObject`, but *filename* is a
:c:expr:`const char*`, which is decoded from the
:term:`filesystem encoding and error handler`.
.. c:function:: int PyRun_InteractiveLoop(FILE *fp, const char *filename)
This is a simplified interface to :c:func:`PyRun_InteractiveLoopFlags` below,
leaving *flags* set to ``NULL``.
.. c:function:: int PyRun_InteractiveLoopFlags(FILE *fp, const char *filename, PyCompilerFlags *flags)
Read and execute statements from a file associated with an interactive device
until EOF is reached. The user will be prompted using ``sys.ps1`` and
``sys.ps2``. *filename* is decoded from the :term:`filesystem encoding and
error handler`. Returns ``0`` at EOF or a negative number upon failure.
.. c:var:: int (*PyOS_InputHook)(void)
Can be set to point to a function with the prototype
``int func(void)``. The function will be called when Python's
interpreter prompt is about to become idle and wait for user input
from the terminal. The return value is ignored. Overriding this
hook can be used to integrate the interpreter's prompt with other
event loops, as done in :file:`Modules/_tkinter.c` in the
Python source code.
The function is called without an :term:`attached thread state`.
.. versionchanged:: 3.12
This function is only called from the
:ref:`main interpreter <sub-interpreter-support>`.
.. c:var:: char* (*PyOS_ReadlineFunctionPointer)(FILE *, FILE *, const char *)
Can be set to point to a function with the prototype
``char *func(FILE *stdin, FILE *stdout, const char *prompt)``,
overriding the default function used to read a single line of input
at the interpreter's prompt. The function is expected to output
the string *prompt* if it's not ``NULL``, and then read a line of
input from the provided standard input file, returning the
resulting string. For example, the :mod:`readline` module sets
this hook to provide line-editing and tab-completion features.
The function is called without an :term:`attached thread state`.
If this pointer is ``NULL``, :c:func:`PyOS_Readline` sets it to the
default implementation, :c:func:`PyOS_Readline`,
before reading input.
The returned string must be null-terminated and include the trailing
newline, if one was read. Return an empty string if the end of the file
is reached before any characters are read. Return ``NULL`` on failure
or interruption; a Python exception may be set.
A non-``NULL`` result must be a string allocated by :c:func:`PyMem_RawMalloc` or
:c:func:`PyMem_RawRealloc`.
.. versionchanged:: 3.4
The result must be allocated by :c:func:`PyMem_RawMalloc` or
:c:func:`PyMem_RawRealloc`, instead of being allocated by
:c:func:`PyMem_Malloc` or :c:func:`PyMem_Realloc`.
.. versionchanged:: 3.12
This function is only called from the
:ref:`main interpreter <sub-interpreter-support>`.
.. c:function:: char *PyOS_Readline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt)
Display *prompt*, if it is not ``NULL``, and read a line from *sys_stdin*.
If both streams are terminals and the call is made from the
:ref:`main interpreter <sub-interpreter-support>`, use
:c:var:`PyOS_ReadlineFunctionPointer`. Otherwise, use the default
implementation, which flushes *sys_stdout* and writes *prompt* to the C
standard error stream.
The returned string follows the contract of
:c:var:`PyOS_ReadlineFunctionPointer`, but the caller must free it with
:c:func:`PyMem_Free`. Return ``NULL`` on failure or interruption; a Python
exception may be set.
.. c:function:: PyObject* PyRun_String(const char *str, int start, PyObject *globals, PyObject *locals)
This is a simplified interface to :c:func:`PyRun_StringFlags` below, leaving
*flags* set to ``NULL``.
.. c:function:: PyObject* PyRun_StringFlags(const char *str, int start, PyObject *globals, PyObject *locals, PyCompilerFlags *flags)
Execute Python source code from *str* in the context specified by the
objects *globals* and *locals* with the compiler flags specified by
*flags*. *globals* must be a dictionary; *locals* can be any object
that implements the mapping protocol. The parameter *start* specifies
the start symbol and must be one of the :ref:`available start symbols <start-symbols>`.
Returns the result of executing the code as a Python object, or ``NULL`` if an
exception was raised.
.. c:function:: PyObject* PyRun_File(FILE *fp, const char *filename, int start, PyObject *globals, PyObject *locals)
This is a simplified interface to :c:func:`PyRun_FileExFlags` below, leaving
*closeit* set to ``0`` and *flags* set to ``NULL``.
.. c:function:: PyObject* PyRun_FileEx(FILE *fp, const char *filename, int start, PyObject *globals, PyObject *locals, int closeit)
This is a simplified interface to :c:func:`PyRun_FileExFlags` below, leaving
*flags* set to ``NULL``.
.. c:function:: PyObject* PyRun_FileFlags(FILE *fp, const char *filename, int start, PyObject *globals, PyObject *locals, PyCompilerFlags *flags)
This is a simplified interface to :c:func:`PyRun_FileExFlags` below, leaving
*closeit* set to ``0``.
.. c:function:: PyObject* PyRun_FileExFlags(FILE *fp, const char *filename, int start, PyObject *globals, PyObject *locals, int closeit, PyCompilerFlags *flags)
Similar to :c:func:`PyRun_StringFlags`, but the Python source code is read from
*fp* instead of an in-memory string. *filename* should be the name of the file,
it is decoded from the :term:`filesystem encoding and error handler`.
If *closeit* is true, the file is closed before :c:func:`PyRun_FileExFlags`
returns.
.. c:function:: PyObject* Py_CompileString(const char *str, const char *filename, int start)
This is a simplified interface to :c:func:`Py_CompileStringFlags` below, leaving
*flags* set to ``NULL``.
.. c:function:: PyObject* Py_CompileStringFlags(const char *str, const char *filename, int start, PyCompilerFlags *flags)
This is a simplified interface to :c:func:`Py_CompileStringExFlags` below, with
*optimize* set to ``-1``.
.. c:function:: PyObject* Py_CompileStringObject(const char *str, PyObject *filename, int start, PyCompilerFlags *flags, int optimize)
Parse and compile the Python source code in *str*, returning the resulting code
object. The start symbol is given by *start*; this can be used to constrain the
code which can be compiled and should be :ref:`available start symbols
<start-symbols>`. The filename specified by
*filename* is used to construct the code object and may appear in tracebacks or
:exc:`SyntaxError` exception messages. This returns ``NULL`` if the code
cannot be parsed or compiled.
The integer *optimize* specifies the optimization level of the compiler; a
value of ``-1`` selects the optimization level of the interpreter as given by
:option:`-O` options. Explicit levels are ``0`` (no optimization;
``__debug__`` is true), ``1`` (asserts are removed, ``__debug__`` is false)
or ``2`` (docstrings are removed too).
.. versionadded:: 3.4
.. c:function:: PyObject* Py_CompileStringExFlags(const char *str, const char *filename, int start, PyCompilerFlags *flags, int optimize)
Like :c:func:`Py_CompileStringObject`, but *filename* is a byte string
decoded from the :term:`filesystem encoding and error handler`.
.. versionadded:: 3.2
.. c:function:: PyObject* PyEval_EvalCode(PyObject *co, PyObject *globals, PyObject *locals)
This is a simplified interface to :c:func:`PyEval_EvalCodeEx`, with just
the code object, and global and local variables. The other arguments are
set to ``NULL``.
.. c:function:: PyObject* PyEval_EvalCodeEx(PyObject *co, PyObject *globals, PyObject *locals, PyObject *const *args, int argcount, PyObject *const *kws, int kwcount, PyObject *const *defs, int defcount, PyObject *kwdefs, PyObject *closure)
Evaluate a precompiled code object, given a particular environment for its
evaluation. This environment consists of a dictionary of global variables,
a mapping object of local variables, arrays of arguments, keywords and
defaults, a dictionary of default values for :ref:`keyword-only
<keyword-only_parameter>` arguments and a closure tuple of cells.
.. c:function:: PyObject* PyEval_EvalFrame(PyFrameObject *f)
Evaluate an execution frame. This is a simplified interface to
:c:func:`PyEval_EvalFrameEx`, for backward compatibility.
.. c:function:: PyObject* PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
This is the main, unvarnished function of Python interpretation. The code
object associated with the execution frame *f* is executed, interpreting
bytecode and executing calls as needed. The additional *throwflag*
parameter can mostly be ignored - if true, then it causes an exception
to immediately be thrown; this is used for the :meth:`~generator.throw`
methods of generator objects.
.. versionchanged:: 3.4
This function now includes a debug assertion to help ensure that it
does not silently discard an active exception.
.. c:function:: int PyEval_MergeCompilerFlags(PyCompilerFlags *cf)
This function changes the flags of the current evaluation frame, and returns
true on success, false on failure.
.. c:struct:: PyCompilerFlags
This is the structure used to hold compiler flags. In cases where code is only
being compiled, it is passed as ``int flags``, and in cases where code is being
executed, it is passed as ``PyCompilerFlags *flags``. In this case, ``from
__future__ import`` can modify *flags*.
Whenever ``PyCompilerFlags *flags`` is ``NULL``, :c:member:`~PyCompilerFlags.cf_flags` is treated as
equal to ``0``, and any modification due to ``from __future__ import`` is
discarded.
.. c:member:: int cf_flags
Compiler flags.
.. c:member:: int cf_feature_version
*cf_feature_version* is the minor Python version. It should be
initialized to ``PY_MINOR_VERSION``.
The field is ignored by default, it is used if and only if
``PyCF_ONLY_AST`` flag is set in :c:member:`~PyCompilerFlags.cf_flags`.
.. versionchanged:: 3.8
Added *cf_feature_version* field.
The available compiler flags are accessible as macros:
.. c:namespace:: NULL
.. c:macro:: PyCF_ALLOW_TOP_LEVEL_AWAIT
PyCF_ONLY_AST
PyCF_OPTIMIZED_AST
PyCF_TYPE_COMMENTS
See :ref:`compiler flags <ast-compiler-flags>` in documentation of the
:py:mod:`!ast` Python module, which exports these constants under
the same names.
.. rubric:: Low-level flags
The following flags and masks serve narrow needs of the standard
library and interactive interpreters. Code outside the standard
library rarely has a reason to use them. They are considered
implementation details and may change at any time.
.. c:macro:: PyCF_ALLOW_INCOMPLETE_INPUT
This flag is a private interface between the compiler and the
:mod:`codeop` module. Do not use it; its behavior is unsupported
and may change without warning.
With this flag set, when compilation fails because the source text
ends where more input is expected, for example in the middle of an
indented block or an unterminated string literal, the error raised
is the undocumented ``_IncompleteInputError``, a subclass of
:exc:`SyntaxError`. The :mod:`codeop` module sets this flag,
together with :c:macro:`PyCF_DONT_IMPLY_DEDENT`, to tell input
that is incomplete apart from input with a real syntax error, so
that interactive interpreters know when to prompt for another
line instead of reporting an error.
.. versionadded:: 3.11
.. c:macro:: PyCF_DONT_IMPLY_DEDENT
By default, when compiling with the :c:var:`Py_single_input` start
symbol, reaching the end of the source text implicitly closes any
open indented blocks. With this flag set, open blocks are only
closed if the last line of the source ends with a newline; otherwise,
compilation fails with a :exc:`SyntaxError`:
.. code-block:: c
PyCompilerFlags flags = {
.cf_flags = 0,
.cf_feature_version = PY_MINOR_VERSION,
};
const char *source = "if a:\n pass";
/* The "if" block is closed implicitly;
this returns a code object: */
Py_CompileStringFlags(source, "<input>", Py_single_input, &flags);
/* With the flag, this fails with a SyntaxError,
because the last line does not end with a newline: */
flags.cf_flags = PyCF_DONT_IMPLY_DEDENT;
Py_CompileStringFlags(source, "<input>", Py_single_input, &flags);
The :mod:`codeop` module uses this flag to detect incomplete
interactive input. While the user is still typing inside an
indented block, the source does not yet end with a newline, so it
fails to compile and the user is prompted for another line.
.. c:macro:: PyCF_IGNORE_COOKIE
Read the source text as UTF-8, ignoring its :pep:`263` encoding
declaration ("coding cookie"), if any:
.. code-block:: c
PyCompilerFlags flags = {
.cf_flags = 0,
.cf_feature_version = PY_MINOR_VERSION,
};
const char *source = "# coding: latin-1\ns = '\xe9'\n";
/* The coding cookie is honored: byte 0xE9 is decoded as
Latin-1, and this returns a code object that sets s to "é": */
Py_CompileStringFlags(source, "<input>", Py_file_input, &flags);
/* With the flag, the cookie is ignored and compilation fails
with a SyntaxError, because 0xE9 is not valid UTF-8: */
flags.cf_flags = PyCF_IGNORE_COOKIE;
Py_CompileStringFlags(source, "<input>", Py_file_input, &flags);
The :func:`compile`, :func:`eval` and :func:`exec` built-in functions
set this flag when the source is a :class:`str` object, because they
pass the text to the parser encoded as UTF-8.
.. c:macro:: PyCF_SOURCE_IS_UTF8
Mark the source text as known to be UTF-8 encoded.
The :func:`compile`, :func:`eval` and :func:`exec` built-in functions
set this flag, but it currently has no effect.
The "``PyCF``" flags above can be combined with "``CO_FUTURE``" flags such
as :c:macro:`CO_FUTURE_ANNOTATIONS` to enable features normally
selectable using :ref:`future statements <future>`.
See :ref:`c_codeobject_flags` for a complete list.
The following masks combine several flags:
.. c:macro:: PyCF_MASK
Bitmask of all ``CO_FUTURE`` flags (see :ref:`c_codeobject_flags`),
which select features normally enabled by
:ref:`future statements <future>`.
When code compiled with a ``PyCompilerFlags *flags`` argument
contains a ``from __future__ import`` statement, the flag for the
imported feature is added to *flags*, so that code executed later
in the same context inherits it.
.. c:macro:: PyCF_MASK_OBSOLETE
Do not use this mask in new code. It is kept only so that old
code passing its flags to :func:`compile` keeps working.
Bitmask of flags for obsolete future features that no longer
have any effect.
.. c:macro:: PyCF_COMPILE_MASK
Bitmask of all ``PyCF`` flags that change how the source is
compiled, such as :c:macro:`PyCF_ONLY_AST`.
The :func:`compile` built-in function uses this mask to validate
its *flags* argument.
.. _start-symbols:
Available start symbols
^^^^^^^^^^^^^^^^^^^^^^^
.. c:var:: int Py_eval_input
.. index:: single: Py_CompileString (C function)
The start symbol from the Python grammar for isolated expressions; for use with
:c:func:`Py_CompileString`.
.. c:var:: int Py_file_input
.. index:: single: Py_CompileString (C function)
The start symbol from the Python grammar for sequences of statements as read
from a file or other source; for use with :c:func:`Py_CompileString`. This is
the symbol to use when compiling arbitrarily long Python source code.
.. c:var:: int Py_single_input
.. index:: single: Py_CompileString (C function)
The start symbol from the Python grammar for a single statement; for use with
:c:func:`Py_CompileString`. This is the symbol used for the interactive
interpreter loop.
.. c:var:: int Py_func_type_input
.. index:: single: Py_CompileString (C function)
The start symbol from the Python grammar for a function type; for use with
:c:func:`Py_CompileString`. This is used to parse "signature type comments"
from :pep:`484`.
This requires the :c:macro:`PyCF_ONLY_AST` flag to be set.
.. seealso::
* :py:class:`ast.FunctionType`
* :pep:`484`
.. versionadded:: 3.8
Stack Effects
^^^^^^^^^^^^^
.. seealso::
:py:func:`dis.stack_effect`
.. c:macro:: PY_INVALID_STACK_EFFECT
Sentinel value representing an invalid stack effect.
This is currently equivalent to ``INT_MAX``.
.. versionadded:: 3.8
.. c:function:: int PyCompile_OpcodeStackEffect(int opcode, int oparg)
Compute the stack effect of *opcode* with argument *oparg*.
On success, this function returns the stack effect; on failure, this
returns :c:macro:`PY_INVALID_STACK_EFFECT`.
.. versionadded:: 3.4
.. c:function:: int PyCompile_OpcodeStackEffectWithJump(int opcode, int oparg, int jump)
Similar to :c:func:`PyCompile_OpcodeStackEffect`, but don't include the
stack effect of jumping if *jump* is zero.
If *jump* is ``0``, this will not include the stack effect of jumping, but
if *jump* is ``1`` or ``-1``, this will include it.
On success, this function returns the stack effect; on failure, this
returns :c:macro:`PY_INVALID_STACK_EFFECT`.
.. versionadded:: 3.8