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 Py_eval_input,
Py_file_input, and Py_single_input. These are described
following the functions which accept them as parameters.
Note also that several of these functions take FILE* parameters. One
particular issue which needs to be handled carefully is that the 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 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.
int Py_Main(int argc, wchar_t **argv)
The main program for the standard interpreter. This is made available for
programs which embed Python. The argc and argv parameters should be
prepared exactly as those which are passed to a C program's main()
function (converted to wchar_t according to the user's locale). It is
important to note that the argument list may be modified (but the contents of
the strings pointed to by the argument list are not). The return value will
be 0 if the interpreter exits normally (i.e., without an exception),
1 if the interpreter exits due to an exception, or 2 if the parameter
list does not represent a valid Python command line.
Note that if an otherwise unhandled SystemExit is raised, this
function will not return 1, but exit the process, as long as
Py_InspectFlag is not set.
int PyRun_AnyFile(FILE *fp, const char *filename)
This is a simplified interface to PyRun_AnyFileExFlags() below, leaving
closeit set to 0 and flags set to NULL.
int PyRun_AnyFileFlags(FILE *fp, const char *filename, PyCompilerFlags *flags)
This is a simplified interface to PyRun_AnyFileExFlags() below, leaving
the closeit argument set to 0.
int PyRun_AnyFileEx(FILE *fp, const char *filename, int closeit)
This is a simplified interface to PyRun_AnyFileExFlags() below, leaving
the flags argument set to NULL.
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
PyRun_InteractiveLoop(), otherwise return the result of
PyRun_SimpleFile(). filename is decoded from the filesystem
encoding (sys.getfilesystemencoding()). If filename is NULL, this
function uses "???" as the filename.
int PyRun_SimpleString(const char *command)
This is a simplified interface to PyRun_SimpleStringFlags() below,
leaving the PyCompilerFlags* argument set to NULL.
int PyRun_SimpleStringFlags(const char *command, PyCompilerFlags *flags)
Executes the Python source code from command in the __main__ module
according to the flags argument. If __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 SystemExit is raised, this
function will not return -1, but exit the process, as long as
Py_InspectFlag is not set.
int PyRun_SimpleFile(FILE *fp, const char *filename)
This is a simplified interface to PyRun_SimpleFileExFlags() below,
leaving closeit set to 0 and flags set to NULL.
int PyRun_SimpleFileEx(FILE *fp, const char *filename, int closeit)
This is a simplified interface to PyRun_SimpleFileExFlags() below,
leaving flags set to NULL.
int PyRun_SimpleFileExFlags(FILE *fp, const char *filename, int closeit, PyCompilerFlags *flags)
Similar to 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 the filesystem encoding
(sys.getfilesystemencoding()). If closeit is true, the file is
closed before PyRun_SimpleFileExFlags returns.
int PyRun_InteractiveOne(FILE *fp, const char *filename)
This is a simplified interface to PyRun_InteractiveOneFlags() below,
leaving flags set to NULL.
int PyRun_InteractiveOneFlags(FILE *fp, const char *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 is decoded from the
filesystem encoding (sys.getfilesystemencoding()).
Returns 0 when the input was
executed successfully, -1 if there was an exception, or an error code
from the errcode.h include file distributed as part of Python if
there was a parse error. (Note that errcode.h is not included by
Python.h, so must be included specifically if needed.)
int PyRun_InteractiveLoop(FILE *fp, const char *filename)
This is a simplified interface to PyRun_InteractiveLoopFlags() below,
leaving flags set to NULL.
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 filesystem encoding
(sys.getfilesystemencoding()). Returns 0 at EOF or a negative
number upon failure.
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 the Modules/_tkinter.c in the
Python source code.
char* (*PyOS_ReadlineFunctionPointer)(FILE *, FILE *, const char *)
Can be set to point to a function with the prototype
char *func(FILE *stdin, FILE *stdout, 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 readline module sets
this hook to provide line-editing and tab-completion features.
The result must be a string allocated by PyMem_RawMalloc() or
PyMem_RawRealloc(), or NULL if an error occurred.
Changed in version 3.4: The result must be allocated by PyMem_RawMalloc() or
PyMem_RawRealloc(), instead of being allocated by
PyMem_Malloc() or PyMem_Realloc().
struct _node* PyParser_SimpleParseString(const char *str, int start)
This is a simplified interface to
PyParser_SimpleParseStringFlagsFilename() below, leaving filename set
to NULL and flags set to 0.
struct _node* PyParser_SimpleParseStringFlags(const char *str, int start, int flags)
This is a simplified interface to
PyParser_SimpleParseStringFlagsFilename() below, leaving filename set
to NULL.
struct _node* PyParser_SimpleParseStringFlagsFilename(const char *str, const char *filename, int start, int flags)
Parse Python source code from str using the start token start according to
the flags argument. The result can be used to create a code object which can
be evaluated efficiently. This is useful if a code fragment must be evaluated
many times. filename is decoded from the filesystem encoding
(sys.getfilesystemencoding()).
struct _node* PyParser_SimpleParseFile(FILE *fp, const char *filename, int start)
This is a simplified interface to PyParser_SimpleParseFileFlags() below,
leaving flags set to 0.
struct _node* PyParser_SimpleParseFileFlags(FILE *fp, const char *filename, int start, int flags)
Similar to PyParser_SimpleParseStringFlagsFilename(), but the Python
source code is read from fp instead of an in-memory string.
PyObject* PyRun_String(const char *str, int start, PyObject *globals, PyObject *locals)
Return value: New reference.This is a simplified interface to PyRun_StringFlags() below, leaving
flags set to NULL.
PyObject* PyRun_StringFlags(const char *str, int start, PyObject *globals, PyObject *locals, PyCompilerFlags *flags)
Return value: New reference.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 token that should be used to parse the source code.
Returns the result of executing the code as a Python object, or NULL if an exception was raised.
PyObject* PyRun_File(FILE *fp, const char *filename, int start, PyObject *globals, PyObject *locals)
Return value: New reference.This is a simplified interface to PyRun_FileExFlags() below, leaving
closeit set to 0 and flags set to NULL.
PyObject* PyRun_FileEx(FILE *fp, const char *filename, int start, PyObject *globals, PyObject *locals, int closeit)
Return value: New reference.This is a simplified interface to PyRun_FileExFlags() below, leaving
flags set to NULL.
PyObject* PyRun_FileFlags(FILE *fp, const char *filename, int start, PyObject *globals, PyObject *locals, PyCompilerFlags *flags)
Return value: New reference.This is a simplified interface to PyRun_FileExFlags() below, leaving
closeit set to 0.
PyObject* PyRun_FileExFlags(FILE *fp, const char *filename, int start, PyObject *globals, PyObject *locals, int closeit, PyCompilerFlags *flags)
Return value: New reference.Similar to 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 filesystem encoding (sys.getfilesystemencoding()).
If closeit is true, the file is closed before PyRun_FileExFlags()
returns.
PyObject* Py_CompileString(const char *str, const char *filename, int start)
Return value: New reference.This is a simplified interface to Py_CompileStringFlags() below, leaving
flags set to NULL.
PyObject* Py_CompileStringFlags(const char *str, const char *filename, int start, PyCompilerFlags *flags)
Return value: New reference.This is a simplified interface to Py_CompileStringExFlags() below, with
optimize set to -1.
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 token is given by start; this can be used to constrain the
code which can be compiled and should be Py_eval_input,
Py_file_input, or Py_single_input. The filename specified by
filename is used to construct the code object and may appear in tracebacks or
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
-O options. Explicit levels are 0 (no optimization;
__debug__ is true), 1 (asserts are removed, __debug__ is false)
or 2 (docstrings are removed too).
New in version 3.4.
PyObject* Py_CompileStringExFlags(const char *str, const char *filename, int start, PyCompilerFlags *flags, int optimize)
Like Py_CompileStringObject(), but filename is a byte string
decoded from the filesystem encoding (os.fsdecode()).
New in version 3.2.
PyObject* PyEval_EvalCode(PyObject *co, PyObject *globals, PyObject *locals)
Return value: New reference.This is a simplified interface to PyEval_EvalCodeEx(), with just
the code object, and global and local variables. The other arguments are
set to NULL.
PyObject* PyEval_EvalCodeEx(PyObject *co, PyObject *globals, PyObject *locals, PyObject **args, int argcount, PyObject **kws, int kwcount, PyObject **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 keyword-only arguments and a closure tuple of cells.
PyFrameObject
The C structure of the objects used to describe frame objects. The fields of this type are subject to change at any time.
PyObject* PyEval_EvalFrame(PyFrameObject *f)
Evaluate an execution frame. This is a simplified interface to
PyEval_EvalFrameEx(), for backward compatibility.
PyObject* PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
This is the main, unvarnished function of Python interpretation. It is
literally 2000 lines long. 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
throw() methods of generator objects.
Changed in version 3.4: This function now includes a debug assertion to help ensure that it does not silently discard an active exception.
int PyEval_MergeCompilerFlags(PyCompilerFlags *cf)
This function changes the flags of the current evaluation frame, and returns true on success, false on failure.
int Py_eval_input
The start symbol from the Python grammar for isolated expressions; for use with
Py_CompileString().
int Py_file_input
The start symbol from the Python grammar for sequences of statements as read
from a file or other source; for use with Py_CompileString(). This is
the symbol to use when compiling arbitrarily long Python source code.
int Py_single_input
The start symbol from the Python grammar for a single statement; for use with
Py_CompileString(). This is the symbol used for the interactive
interpreter loop.
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, cf_flags is treated as
equal to 0, and any modification due to from __future__ import is
discarded.
struct PyCompilerFlags {
int cf_flags;
}
int CO_FUTURE_DIVISION
This bit can be set in flags to cause division operator / to be
interpreted as "true division" according to PEP 238.