Configuração de Inicialização do Python¶
Novo na versão 3.8.
Estruturas:
Funções:
A pré-configuração (tipo PyPreConfig
) é armazenado em _PyRuntime.preconfig
e a configuração (tipo PyConfig
) é armazenado em PyInterpreterState.config
.
Veja também Inicialização, Finalização e Threads.
Ver também
PEP 587 “Configuração da inicialização do Python”.
PyWideStringList¶
-
PyWideStringList
¶ Lista de strings
wchar_t*
.Se length é diferente de zero, items deve ser diferente de
NULL
e todas as strings devem ser diferentes deNULL
.Métodos:
-
PyStatus
PyWideStringList_Append
(PyWideStringList *list, const wchar_t *item)¶ Anexa item a list.
Python deve ser inicializado previamente antes de chamar essa função.
-
PyStatus
PyWideStringList_Insert
(PyWideStringList *list, Py_ssize_t index, const wchar_t *item)¶ Insere item na list na posição index.
Se index for maior ou igual ao comprimento da list, anexa o item a list.
index deve ser maior que ou igual a 0.
Python deve ser inicializado previamente antes de chamar essa função.
Campos de estrutura:
-
Py_ssize_t
length
¶ Comprimento da lista.
-
wchar_t**
items
¶ Itens da lista.
-
PyStatus
PyStatus¶
-
PyStatus
¶ Estrutura para armazenar o status de uma função de inicialização: sucesso, erro ou saída.
Para um erro, ela pode armazenar o nome da função C que criou o erro.
Campos de estrutura:
-
int
exitcode
¶ Código de saída. Argumento passado para
exit()
.
-
const char *
err_msg
¶ Mensagem de erro.
-
const char *
func
¶ Nome da função que criou um erro. Pode ser
NULL
.
Funções para criar um status:
Funções para manipular um status:
-
int
PyStatus_Exception
(PyStatus status)¶ O status é um erro ou uma saída? Se verdadeiro, a exceção deve ser tratada; chamando
Py_ExitStatusException()
, por exemplo.
-
int
Nota
Internamente, Python usa macros que definem PyStatus.func
, enquanto funções para criar um status definem func
para NULL
.
Exemplo:
PyStatus alloc(void **ptr, size_t size)
{
*ptr = PyMem_RawMalloc(size);
if (*ptr == NULL) {
return PyStatus_NoMemory();
}
return PyStatus_Ok();
}
int main(int argc, char **argv)
{
void *ptr;
PyStatus status = alloc(&ptr, 16);
if (PyStatus_Exception(status)) {
Py_ExitStatusException(status);
}
PyMem_Free(ptr);
return 0;
}
PyPreConfig¶
-
PyPreConfig
¶ Estrutura usada para pré-inicializar o Python:
Define o alocador de memória do Python
Configura a localidade LC_CTYPE
Define o modo UTF-8
A função para inicializar uma pré-configuração:
-
void
PyPreConfig_InitPythonConfig
(PyPreConfig *preconfig)¶ Inicializa a pré-configuração com Configuração do Python.
-
void
PyPreConfig_InitIsolatedConfig
(PyPreConfig *preconfig)¶ Inicializa a pré-configuração com Configuração isolada.
Campos de estrutura:
-
int
allocator
¶ Nome do alocador de memória:
PYMEM_ALLOCATOR_NOT_SET
(0
): não altera os alocadores de memória (usa o padrão)PYMEM_ALLOCATOR_DEFAULT
(1
): alocadores de memória padrãoPYMEM_ALLOCATOR_DEBUG
(2
): alocadores de memória padrão com ganchos de depuraçãoPYMEM_ALLOCATOR_MALLOC
(3
): força o uso demalloc()
PYMEM_ALLOCATOR_MALLOC_DEBUG
(4
): força o uso demalloc()
com ganchos de depuraçãoPYMEM_ALLOCATOR_PYMALLOC
(5
): Alocador de memória do Python pymallocPYMEM_ALLOCATOR_PYMALLOC_DEBUG
(6
): alocador de memória do Python pymalloc com ganchos de depuração
PYMEM_ALLOCATOR_PYMALLOC
ePYMEM_ALLOCATOR_PYMALLOC_DEBUG
não são suportados se Python estiver configurado usando--without-pymalloc
Veja Gerenciamento de memória.
-
int
configure_locale
¶ Definir a localidade LC_CTYPE para a localidade preferida do usuário? Se for igual a 0, define
coerce_c_locale
ecoerce_c_locale_warn
para 0.
-
int
coerce_c_locale
¶ Se for igual a 2, força a localidade C; se for igual a 1, lê a localidade LC_CTYPE para decidir se deve ser forçado.
-
int
coerce_c_locale_warn
¶ Se diferente de zero, emite um aviso se a localidade C for forçada.
-
int
dev_mode
¶ Veja
PyConfig.dev_mode
.
-
int
isolated
¶ Veja
PyConfig.isolated
.
-
int
legacy_windows_fs_encoding
(Windows only)¶ Se diferente de zero, desabilita o modo UTF-8, define a codificação do sistema de arquivos Python para
mbcs
, define o tratador de erros do sistema de arquivos parareplace
.Disponível apenas no Windows. A macro
#ifdef MS_WINDOWS
pode ser usada para código específico do Windows.
-
int
parse_argv
¶ Se diferente de zero,
Py_PreInitializeFromArgs()
ePy_PreInitializeFromBytesArgs()
analisam seu argumentoargv
da mesma forma que o Python regular analisa argumentos de linha de comando: veja Argumentos de linha de comando.
-
int
use_environment
¶ Veja
PyConfig.use_environment
.
-
int
utf8_mode
¶ Se não zero, habilita o modo UTF-8.
Preinitialization with PyPreConfig¶
Funções para pré-inicializar Python:
-
PyStatus
Py_PreInitialize
(const PyPreConfig *preconfig)¶ Pré-inicializa o Python a partir da pré-configuração preconfig.
-
PyStatus
Py_PreInitializeFromBytesArgs
(const PyPreConfig *preconfig, int argc, char * const *argv)¶ Preinitialize Python from preconfig preconfiguration and command line arguments (bytes strings).
-
PyStatus
Py_PreInitializeFromArgs
(const PyPreConfig *preconfig, int argc, wchar_t * const * argv)¶ Preinitialize Python from preconfig preconfiguration and command line arguments (wide strings).
O chamador é responsável por manipular exceções (erro ou saída) usando PyStatus_Exception()
e Py_ExitStatusException()
.
For Python Configuration
(PyPreConfig_InitPythonConfig()
), if Python is initialized with
command line arguments, the command line arguments must also be passed to
preinitialize Python, since they have an effect on the pre-configuration
like encodings. For example, the -X utf8
command line option
enables the UTF-8 Mode.
PyMem_SetAllocator()
pode ser chamado depois de Py_PreInitialize()
e antes de Py_InitializeFromConfig()
para instalar um alocador de memória personalizado. Ele pode ser chamado antes de Py_PreInitialize()
se PyPreConfig.allocator
estiver definido como PYMEM_ALLOCATOR_NOT_SET
.
Python memory allocation functions like PyMem_RawMalloc()
must not be
used before Python preinitialization, whereas calling directly malloc()
and
free()
is always safe. Py_DecodeLocale()
must not be called before
the preinitialization.
Example using the preinitialization to enable the UTF-8 Mode:
PyStatus status;
PyPreConfig preconfig;
PyPreConfig_InitPythonConfig(&preconfig);
preconfig.utf8_mode = 1;
status = Py_PreInitialize(&preconfig);
if (PyStatus_Exception(status)) {
Py_ExitStatusException(status);
}
/* at this point, Python will speak UTF-8 */
Py_Initialize();
/* ... use Python API here ... */
Py_Finalize();
PyConfig¶
-
PyConfig
¶ Estrutura contendo a maioria dos parâmetros para configurar o Python.
Structure methods:
-
void
PyConfig_InitPythonConfig
(PyConfig *config)¶ Initialize configuration with Python Configuration.
-
void
PyConfig_InitIsolatedConfig
(PyConfig *config)¶ Initialize configuration with Isolated Configuration.
-
PyStatus
PyConfig_SetString
(PyConfig *config, wchar_t * const *config_str, const wchar_t *str)¶ Copy the wide character string str into
*config_str
.Preinitialize Python if needed.
-
PyStatus
PyConfig_SetBytesString
(PyConfig *config, wchar_t * const *config_str, const char *str)¶ Decode str using
Py_DecodeLocale()
and set the result into*config_str
.Preinitialize Python if needed.
-
PyStatus
PyConfig_SetArgv
(PyConfig *config, int argc, wchar_t * const *argv)¶ Set command line arguments from wide character strings.
Preinitialize Python if needed.
-
PyStatus
PyConfig_SetBytesArgv
(PyConfig *config, int argc, char * const *argv)¶ Set command line arguments: decode bytes using
Py_DecodeLocale()
.Preinitialize Python if needed.
-
PyStatus
PyConfig_SetWideStringList
(PyConfig *config, PyWideStringList *list, Py_ssize_t length, wchar_t **items)¶ Set the list of wide strings list to length and items.
Preinitialize Python if needed.
-
PyStatus
PyConfig_Read
(PyConfig *config)¶ Read all Python configuration.
Fields which are already initialized are left unchanged.
Preinitialize Python if needed.
Most
PyConfig
methods preinitialize Python if needed. In that case, the Python preinitialization configuration in based on thePyConfig
. If configuration fields which are in common withPyPreConfig
are tuned, they must be set before calling aPyConfig
method:Moreover, if
PyConfig_SetArgv()
orPyConfig_SetBytesArgv()
is used, this method must be called first, before other methods, since the preinitialization configuration depends on command line arguments (ifparse_argv
is non-zero).The caller of these methods is responsible to handle exceptions (error or exit) using
PyStatus_Exception()
andPy_ExitStatusException()
.Campos de estrutura:
-
PyWideStringList
argv
¶ Command line arguments,
sys.argv
. Seeparse_argv
to parseargv
the same way the regular Python parses Python command line arguments. Ifargv
is empty, an empty string is added to ensure thatsys.argv
always exists and is never empty.
-
wchar_t*
base_exec_prefix
¶
-
wchar_t*
base_executable
¶ sys._base_executable
:__PYVENV_LAUNCHER__
environment variable value, or copy ofPyConfig.executable
.
-
wchar_t*
base_prefix
¶
-
int
buffered_stdio
¶ If equals to 0, enable unbuffered mode, making the stdout and stderr streams unbuffered.
stdin is always opened in buffered mode.
-
int
bytes_warning
¶ If equals to 1, issue a warning when comparing
bytes
orbytearray
withstr
, or comparingbytes
withint
. If equal or greater to 2, raise aBytesWarning
exception.
-
wchar_t*
check_hash_pycs_mode
¶ Control the validation behavior of hash-based
.pyc
files (see PEP 552):--check-hash-based-pycs
command line option value.Valid values:
always
,never
anddefault
.The default value is:
default
.
-
int
configure_c_stdio
¶ If non-zero, configure C standard streams (
stdio
,stdout
,stdout
). For example, set their mode toO_BINARY
on Windows.
-
int
dump_refs
¶ If non-zero, dump all objects which are still alive at exit.
Require a debug build of Python (
Py_REF_DEBUG
macro must be defined).
-
wchar_t*
exec_prefix
¶
-
wchar_t*
executable
¶
-
int
faulthandler
¶ If non-zero, call
faulthandler.enable()
at startup.
-
wchar_t*
filesystem_encoding
¶ Filesystem encoding,
sys.getfilesystemencoding()
.
-
wchar_t*
filesystem_errors
¶ Filesystem encoding errors,
sys.getfilesystemencodeerrors()
.
-
unsigned long
hash_seed
¶
-
int
use_hash_seed
¶ Randomized hash function seed.
If
use_hash_seed
is zero, a seed is chosen randomly at Pythonstartup, andhash_seed
is ignored.
-
wchar_t*
home
¶ Python home directory.
Initialized from
PYTHONHOME
environment variable value by default.
-
int
import_time
¶ If non-zero, profile import time.
-
int
inspect
¶ Enter interactive mode after executing a script or a command.
-
int
install_signal_handlers
¶ Install signal handlers?
-
int
interactive
¶ Interactive mode.
-
int
isolated
¶ If greater than 0, enable isolated mode:
sys.path
contains neither the script’s directory (computed fromargv[0]
or the current directory) nor the user’s site-packages directory.Python REPL doesn’t import
readline
nor enable default readline configuration on interactive prompts.Set
use_environment
anduser_site_directory
to 0.
-
int
legacy_windows_stdio
¶ If non-zero, use
io.FileIO
instead ofio.WindowsConsoleIO
forsys.stdin
,sys.stdout
andsys.stderr
.Disponível apenas no Windows. A macro
#ifdef MS_WINDOWS
pode ser usada para código específico do Windows.
-
int
malloc_stats
¶ If non-zero, dump statistics on Python pymalloc memory allocator at exit.
The option is ignored if Python is built using
--without-pymalloc
.
-
wchar_t*
pythonpath_env
¶ Module search paths as a string separated by
DELIM
(os.path.pathsep
).Initialized from
PYTHONPATH
environment variable value by default.
-
PyWideStringList
module_search_paths
¶
-
int
module_search_paths_set
¶ sys.path
. Ifmodule_search_paths_set
is equal to 0, themodule_search_paths
is overridden by the function calculating the Path Configuration.
-
int
optimization_level
¶ Compilation optimization level:
0: Peephole optimizer (and
__debug__
is set toTrue
)1: Remove assertions, set
__debug__
toFalse
2: Strip docstrings
-
int
parse_argv
¶ If non-zero, parse
argv
the same way the regular Python command line arguments, and strip Python arguments fromargv
: see Command Line Arguments.
-
int
parser_debug
¶ If non-zero, turn on parser debugging output (for expert only, depending on compilation options).
-
int
pathconfig_warnings
¶ If equal to 0, suppress warnings when calculating the Path Configuration (Unix only, Windows does not log any warning). Otherwise, warnings are written into
stderr
.
-
wchar_t*
prefix
¶
-
wchar_t*
program_name
¶ Program name. Used to initialize
executable
, and in early error messages.
-
wchar_t*
pycache_prefix
¶ sys.pycache_prefix
:.pyc
cache prefix.If
NULL
,sys.pycache_prefix
is set toNone
.
-
int
quiet
¶ Quiet mode. For example, don’t display the copyright and version messages in interactive mode.
-
wchar_t*
run_command
¶ python3 -c COMMAND
argument. Used byPy_RunMain()
.
-
wchar_t*
run_filename
¶ python3 FILENAME
argument. Used byPy_RunMain()
.
-
wchar_t*
run_module
¶ python3 -m MODULE
argument. Used byPy_RunMain()
.
-
int
show_alloc_count
¶ Show allocation counts at exit?
Set to 1 by
-X showalloccount
command line option.Need a special Python build with
COUNT_ALLOCS
macro defined.
-
int
show_ref_count
¶ Show total reference count at exit?
Set to 1 by
-X showrefcount
command line option.Need a debug build of Python (
Py_REF_DEBUG
macro must be defined).
-
int
skip_source_first_line
¶ Skip the first line of the source?
-
wchar_t*
stdio_encoding
¶
-
wchar_t*
stdio_errors
¶ Encoding and encoding errors of
sys.stdin
,sys.stdout
andsys.stderr
.
-
int
tracemalloc
¶ If non-zero, call
tracemalloc.start()
at startup.
-
int
use_environment
¶ If greater than 0, use environment variables.
-
int
verbose
¶ If non-zero, enable verbose mode.
-
PyWideStringList
warnoptions
¶ sys.warnoptions
: options of thewarnings
module to build warnings filters: lowest to highest priority.The
warnings
module addssys.warnoptions
in the reverse order: the lastPyConfig.warnoptions
item becomes the first item ofwarnings.filters
which is checked first (highest priority).
-
int
write_bytecode
¶ If non-zero, write
.pyc
files.sys.dont_write_bytecode
is initialized to the inverted value ofwrite_bytecode
.
-
PyWideStringList
xoptions
¶
-
void
If parse_argv
is non-zero, argv
arguments are parsed the same
way the regular Python parses command line arguments, and Python
arguments are stripped from argv
: see Command Line Arguments.
The xoptions
options are parsed to set other options: see -X
option.
Initialization with PyConfig¶
Function to initialize Python:
-
PyStatus
Py_InitializeFromConfig
(const PyConfig *config)¶ Initialize Python from config configuration.
O chamador é responsável por manipular exceções (erro ou saída) usando PyStatus_Exception()
e Py_ExitStatusException()
.
If PyImport_FrozenModules
, PyImport_AppendInittab()
or
PyImport_ExtendInittab()
are used, they must be set or called after Python
preinitialization and before the Python initialization.
Example setting the program name:
void init_python(void)
{
PyStatus status;
PyConfig config;
PyConfig_InitPythonConfig(&config);
/* Set the program name. Implicitly preinitialize Python. */
status = PyConfig_SetString(&config, &config.program_name,
L"/path/to/my_program");
if (PyStatus_Exception(status)) {
goto fail;
}
status = Py_InitializeFromConfig(&config);
if (PyStatus_Exception(status)) {
goto fail;
}
PyConfig_Clear(&config);
return;
fail:
PyConfig_Clear(&config);
Py_ExitStatusException(status);
}
More complete example modifying the default configuration, read the configuration, and then override some parameters:
PyStatus init_python(const char *program_name)
{
PyStatus status;
PyConfig config;
PyConfig_InitPythonConfig(&config);
/* Set the program name before reading the configuration
(decode byte string from the locale encoding).
Implicitly preinitialize Python. */
status = PyConfig_SetBytesString(&config, &config.program_name,
program_name);
if (PyStatus_Exception(status)) {
goto done;
}
/* Read all configuration at once */
status = PyConfig_Read(&config);
if (PyStatus_Exception(status)) {
goto done;
}
/* Append our custom search path to sys.path */
status = PyWideStringList_Append(&config.module_search_paths,
L"/path/to/more/modules");
if (PyStatus_Exception(status)) {
goto done;
}
/* Override executable computed by PyConfig_Read() */
status = PyConfig_SetString(&config, &config.executable,
L"/path/to/my_executable");
if (PyStatus_Exception(status)) {
goto done;
}
status = Py_InitializeFromConfig(&config);
done:
PyConfig_Clear(&config);
return status;
}
Isolated Configuration¶
PyPreConfig_InitIsolatedConfig()
and
PyConfig_InitIsolatedConfig()
functions create a configuration to
isolate Python from the system. For example, to embed Python into an
application.
This configuration ignores global configuration variables, environments
variables, command line arguments (PyConfig.argv
is not parsed)
and user site directory. The C standard streams (ex: stdout
) and the
LC_CTYPE locale are left unchanged. Signal handlers are not installed.
Configuration files are still used with this configuration. Set the Path Configuration (“output fields”) to ignore these configuration files and avoid the function computing the default path configuration.
Configuração do Python¶
PyPreConfig_InitPythonConfig()
and PyConfig_InitPythonConfig()
functions create a configuration to build a customized Python which behaves as
the regular Python.
Environments variables and command line arguments are used to configure Python, whereas global configuration variables are ignored.
This function enables C locale coercion (PEP 538) and UTF-8 Mode
(PEP 540) depending on the LC_CTYPE locale, PYTHONUTF8
and
PYTHONCOERCECLOCALE
environment variables.
Exemplo de Python personalizado sendo executado sempre em um modo isolado:
int main(int argc, char **argv)
{
PyStatus status;
PyConfig config;
PyConfig_InitPythonConfig(&config);
config.isolated = 1;
/* Decode command line arguments.
Implicitly preinitialize Python (in isolated mode). */
status = PyConfig_SetBytesArgv(&config, argc, argv);
if (PyStatus_Exception(status)) {
goto fail;
}
status = Py_InitializeFromConfig(&config);
if (PyStatus_Exception(status)) {
goto fail;
}
PyConfig_Clear(&config);
return Py_RunMain();
fail:
PyConfig_Clear(&config);
if (PyStatus_IsExit(status)) {
return status.exitcode;
}
/* Display the error message and exit the process with
non-zero exit code */
Py_ExitStatusException(status);
}
Path Configuration¶
PyConfig
contains multiple fields for the path configuration:
Path configuration inputs:
current working directory: to get absolute paths
PATH
environment variable to get the program full path (fromPyConfig.program_name
)__PYVENV_LAUNCHER__
environment variable(Windows only) Application paths in the registry under “SoftwarePythonPythonCoreX.YPythonPath” of HKEY_CURRENT_USER and HKEY_LOCAL_MACHINE (where X.Y is the Python version).
Path configuration output fields:
If at least one “output field” is not set, Python calculates the path
configuration to fill unset fields. If
module_search_paths_set
is equal to 0,
module_search_paths
is overridden and
module_search_paths_set
is set to 1.
It is possible to completely ignore the function calculating the default
path configuration by setting explicitly all path configuration output
fields listed above. A string is considered as set even if it is non-empty.
module_search_paths
is considered as set if
module_search_paths_set
is set to 1. In this case, path
configuration input fields are ignored as well.
Set pathconfig_warnings
to 0 to suppress warnings when
calculating the path configuration (Unix only, Windows does not log any warning).
If base_prefix
or base_exec_prefix
fields are not set, they inherit their value from prefix
and exec_prefix
respectively.
Py_RunMain()
and Py_Main()
modify sys.path
:
If
run_filename
is set and is a directory which contains a__main__.py
script, prependrun_filename
tosys.path
.If
isolated
is zero:If
run_module
is set, prepend the current directory tosys.path
. Do nothing if the current directory cannot be read.If
run_filename
is set, prepend the directory of the filename tosys.path
.Otherwise, prepend an empty string to
sys.path
.
If site_import
is non-zero, sys.path
can be
modified by the site
module. If
user_site_directory
is non-zero and the user’s
site-package directory exists, the site
module appends the user’s
site-package directory to sys.path
.
The following configuration files are used by the path configuration:
pyvenv.cfg
python._pth
(Windows only)pybuilddir.txt
(Unix only)
The __PYVENV_LAUNCHER__
environment variable is used to set
PyConfig.base_executable
Py_RunMain()¶
-
int
Py_RunMain
(void)¶ Execute the command (
PyConfig.run_command
), the script (PyConfig.run_filename
) or the module (PyConfig.run_module
) specified on the command line or in the configuration.By default and when if
-i
option is used, run the REPL.Finally, finalizes Python and returns an exit status that can be passed to the
exit()
function.
See Python Configuration for an example of
customized Python always running in isolated mode using
Py_RunMain()
.
Multi-Phase Initialization Private Provisional API¶
This section is a private provisional API introducing multi-phase initialization, the core feature of the PEP 432:
“Core” initialization phase, “bare minimum Python”:
“Main” initialization phase, Python is fully initialized:
Install and configure
importlib
;Apply the Path Configuration;
Install signal handlers;
Finish
sys
module initialization (ex: createsys.stdout
andsys.path
);Enable optional features like
faulthandler
andtracemalloc
;Import the
site
module;etc.
Private provisional API:
PyConfig._init_main
: if set to 0,Py_InitializeFromConfig()
stops at the “Core” initialization phase.
-
PyStatus
_Py_InitializeMain
(void)¶ Move to the “Main” initialization phase, finish the Python initialization.
No module is imported during the “Core” phase and the importlib
module is
not configured: the Path Configuration is only
applied during the “Main” phase. It may allow to customize Python in Python to
override or tune the Path Configuration, maybe
install a custom sys.meta_path
importer or an import hook, etc.
It may become possible to calculatin the Path Configuration in Python, after the Core phase and before the Main phase, which is one of the PEP 432 motivation.
The “Core” phase is not properly defined: what should be and what should not be available at this phase is not specified yet. The API is marked as private and provisional: the API can be modified or even be removed anytime until a proper public API is designed.
Example running Python code between “Core” and “Main” initialization phases:
void init_python(void)
{
PyStatus status;
PyConfig config;
PyConfig_InitPythonConfig(&config);
config._init_main = 0;
/* ... customize 'config' configuration ... */
status = Py_InitializeFromConfig(&config);
PyConfig_Clear(&config);
if (PyStatus_Exception(status)) {
Py_ExitStatusException(status);
}
/* Use sys.stderr because sys.stdout is only created
by _Py_InitializeMain() */
int res = PyRun_SimpleString(
"import sys; "
"print('Run Python code before _Py_InitializeMain', "
"file=sys.stderr)");
if (res < 0) {
exit(1);
}
/* ... put more configuration code here ... */
status = _Py_InitializeMain();
if (PyStatus_Exception(status)) {
Py_ExitStatusException(status);
}
}