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
,
,
, and
. 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.
intPyRun_AnyFile(FILE*fp, constchar*filename)
This is a simplified interface to
below, leaving closeit set to 0 and flags set to NULL.
intPyRun_AnyFileFlags(FILE*fp, constchar*filename,
*flags)
This is a simplified interface to
below, leaving the closeit argument set to 0.
intPyRun_AnyFileEx(FILE*fp, constchar*filename, intcloseit)
This is a simplified interface to
below, leaving the flags argument set to NULL.
intPyRun_AnyFileExFlags(FILE*fp, constchar*filename, intcloseit,
*flags)
If fp refers to a file associated with an interactive device (console or terminal input or Unix pseudo-terminal), return the value of
, otherwise return the result of
. filename is decoded from the filesystem encoding (
). If filename is NULL, this function uses "???" as the filename. If closeit is true, the file is closed before PyRun_SimpleFileExFlags() returns.
intPyRun_SimpleString(constchar*command)
This is a simplified interface to
below, leaving the
* argument set to NULL.
intPyRun_SimpleStringFlags(constchar*command,
*flags)
Executes the Python source code from command in the
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
is raised, this function will not return -1, but exit the process, as long as
is zero.
intPyRun_SimpleFile(FILE*fp, constchar*filename)
This is a simplified interface to
below, leaving closeit set to 0 and flags set to NULL.
intPyRun_SimpleFileEx(FILE*fp, constchar*filename, intcloseit)
This is a simplified interface to
below, leaving flags set to NULL.
intPyRun_SimpleFileExFlags(FILE*fp, constchar*filename, intcloseit,
*flags)
Similar to
, 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
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.
intPyRun_InteractiveOneObject(FILE*fp,
*filename,
*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
object.
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.)
intPyRun_InteractiveOne(FILE*fp, constchar*filename)
This is a simplified interface to
below, leaving flags set to NULL.
intPyRun_InteractiveOneFlags(FILE*fp, constchar*filename,
*flags)
Similar to
, but filename is a constchar*, which is decoded from the
filesystem encoding and error handler
.
intPyRun_InteractiveLoop(FILE*fp, constchar*filename)
This is a simplified interface to
below, leaving flags set to NULL.
intPyRun_InteractiveLoopFlags(FILE*fp, constchar*filename,
*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 and error handler
. Returns 0 at EOF or a negative number upon failure.
int(*PyOS_InputHook)(void)
Part of the
.Can be set to point to a function with the prototype intfunc(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 Modules/_tkinter.c in the Python source code.
Changed in version 3.12: This function is only called from the
.
char*(*PyOS_ReadlineFunctionPointer)(FILE*,FILE*,constchar*)
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
module sets this hook to provide line-editing and tab-completion features.
The result must be a string allocated by
or
, or NULL if an error occurred.
Changed in version 3.12: This function is only called from the
.
*PyRun_String(constchar*str, intstart,
*globals,
*locals)
Return value: New reference.This is a simplified interface to
below, leaving flags set to NULL.
*PyRun_StringFlags(constchar*str, intstart,
*globals,
*locals,
*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 symbol and must be one of the
.
Returns the result of executing the code as a Python object, or NULL if an exception was raised.
*PyRun_File(FILE*fp, constchar*filename, intstart,
*globals,
*locals)
Return value: New reference.This is a simplified interface to
below, leaving closeit set to 0 and flags set to NULL.
*PyRun_FileEx(FILE*fp, constchar*filename, intstart,
*globals,
*locals, intcloseit)
Return value: New reference.This is a simplified interface to
below, leaving flags set to NULL.
*PyRun_FileFlags(FILE*fp, constchar*filename, intstart,
*globals,
*locals,
*flags)
Return value: New reference.This is a simplified interface to
below, leaving closeit set to 0.
*PyRun_FileExFlags(FILE*fp, constchar*filename, intstart,
*globals,
*locals, intcloseit,
*flags)
Return value: New reference.Similar to
, 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 and error handler
. If closeit is true, the file is closed before
returns.
*Py_CompileString(constchar*str, constchar*filename, intstart)
Return value: New reference. Part of the
.This is a simplified interface to
below, leaving flags set to NULL.
*Py_CompileStringFlags(constchar*str, constchar*filename, intstart,
*flags)
Return value: New reference.This is a simplified interface to
below, with optimize set to -1.
*Py_CompileStringObject(constchar*str,
*filename, intstart,
*flags, intoptimize)
Return value: New reference.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
. The filename specified by filename is used to construct the code object and may appear in tracebacks or
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
options. Explicit levels are 0 (no optimization; __debug__ is true), 1 (asserts are removed, __debug__ is false) or 2 (docstrings are removed too).
Added in version 3.4.
*Py_CompileStringExFlags(constchar*str, constchar*filename, intstart,
*flags, intoptimize)
Return value: New reference.Like
, but filename is a byte string decoded from the
filesystem encoding and error handler
.
Added in version 3.2.
*PyEval_EvalCode(
*co,
*globals,
*locals)
Return value: New reference. Part of the
.This is a simplified interface to
, with just the code object, and global and local variables. The other arguments are set to NULL.
*PyEval_EvalCodeEx(
*co,
*globals,
*locals,
*const*args, intargcount,
*const*kws, intkwcount,
*const*defs, intdefcount,
*kwdefs,
*closure)
Return value: New reference. Part of the
.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
arguments and a closure tuple of cells.
*PyEval_EvalFrame(
*f)
Return value: New reference. Part of the
.Evaluate an execution frame. This is a simplified interface to
, for backward compatibility.
*PyEval_EvalFrameEx(
*f, intthrowflag)
Return value: New reference. Part of the
.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
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.
intPyEval_MergeCompilerFlags(
*cf)
This function changes the flags of the current evaluation frame, and returns true on success, false on failure.
structPyCompilerFlags
This is the structure used to hold compiler flags. In cases where code is only being compiled, it is passed as intflags, 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,
is treated as equal to 0, and any modification due to from__future__import is discarded.
intcf_flags
Compiler flags.
intcf_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
.
Changed in version 3.8: Added cf_feature_version field.
The available compiler flags are accessible as macros:
PyCF_ALLOW_TOP_LEVEL_AWAIT
PyCF_ONLY_AST
PyCF_OPTIMIZED_AST
See
in documentation of the ast Python module, which exports these constants under the same names.
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.
PyCF_ALLOW_INCOMPLETE_INPUT
This flag is a private interface between the compiler and the
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
. The
module sets this flag, together with
, 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.
Added in version 3.11.
PyCF_DONT_IMPLY_DEDENT
By default, when compiling with the
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
:
PyCompilerFlagsflags={.cf_flags=0,.cf_feature_version=PY_MINOR_VERSION,};constchar*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
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.
PyCF_IGNORE_COOKIE
Read the source text as UTF-8, ignoring its
encoding declaration (“coding cookie”), if any:
PyCompilerFlagsflags={.cf_flags=0,.cf_feature_version=PY_MINOR_VERSION,};constchar*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
,
and
built-in functions set this flag when the source is a
object, because they pass the text to the parser encoded as UTF-8.
PyCF_SOURCE_IS_UTF8
Mark the source text as known to be UTF-8 encoded. The
,
and
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
to enable features normally selectable using
. See
for a complete list.
The following masks combine several flags:
PyCF_MASK
Bitmask of all CO_FUTURE flags (see
), which select features normally enabled by
. 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.
PyCF_MASK_OBSOLETE
Do not use this mask in new code. It is kept only so that old code passing its flags to
keeps working.
Bitmask of flags for obsolete future features that no longer have any effect.
PyCF_COMPILE_MASK
Bitmask of all PyCF flags that change how the source is compiled, such as
. The
built-in function uses this mask to validate its flags argument.
Available start symbols
intPy_eval_input
The start symbol from the Python grammar for isolated expressions; for use with
.
intPy_file_input
The start symbol from the Python grammar for sequences of statements as read from a file or other source; for use with
. This is the symbol to use when compiling arbitrarily long Python source code.
intPy_single_input
The start symbol from the Python grammar for a single statement; for use with
. This is the symbol used for the interactive interpreter loop.
intPy_func_type_input
The start symbol from the Python grammar for a function type; for use with
. This is used to parse “signature type comments” from
.
This requires the
flag to be set.
Added in version 3.8.
Stack Effects
PY_INVALID_STACK_EFFECT
Sentinel value representing an invalid stack effect.
This is currently equivalent to INT_MAX.
Added in version 3.8.
intPyCompile_OpcodeStackEffect(intopcode, intoparg)
Compute the stack effect of opcode with argument oparg.
On success, this function returns the stack effect; on failure, this returns
.
Added in version 3.4.
intPyCompile_OpcodeStackEffectWithJump(intopcode, intoparg, intjump)
Similar to
, 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
.
Added in version 3.8.