Safe Haskell | None |
---|---|
Language | Haskell98 |
- initialize :: IO ()
- isInitialized :: IO Bool
- finalize :: IO ()
- newInterpreter :: IO (Maybe ThreadState)
- endInterpreter :: ThreadState -> IO ()
- getProgramName :: IO Text
- setProgramName :: Text -> IO ()
- getPrefix :: IO Text
- getExecPrefix :: IO Text
- getProgramFullPath :: IO Text
- getPath :: IO Text
- getVersion :: IO Text
- getPlatform :: IO Text
- getCopyright :: IO Text
- getCompiler :: IO Text
- getBuildInfo :: IO Text
- setArgv :: Text -> [Text] -> IO ()
- getPythonHome :: IO (Maybe Text)
- setPythonHome :: Maybe Text -> IO ()
Documentation
initialize :: IO () Source #
Initialize the Python interpreter. In an application embedding Python,
this should be called before using any other Python/C API computations;
with the exception of setProgramName
, initThreads
,
releaseLock
, and acquireLock
. This initializes the table
of loaded modules (sys.modules
), and creates the fundamental modules
builtins
, main
and sys
. It also initializes the module search
path (sys.path
). It does not set sys.argv
; use setArgv
for that. This
is a no-op when called for a second time (without calling finalize
first). There is no return value; it is a fatal error if the initialization
fails.
isInitialized :: IO Bool Source #
Return True
when the Python interpreter has been initialized, False
if not. After finalize
is called, this returns False
until
initialize
is called again.
Undo all initializations made by initialize
and subsequent use of
Python/C API computations, and destroy all sub-interpreters (see
newInterpreter
below) that were created and not yet destroyed since the
last call to initialize
. Ideally, this frees all memory allocated by the
Python interpreter. This is a no-op when called for a second time (without
calling initialize
again first). There is no return value; errors during
finalization are ignored.
This computation is provided for a number of reasons. An embedding application might want to restart Python without having to restart the application itself. An application that has loaded the Python interpreter from a dynamically loadable library (or DLL) might want to free all memory allocated by Python before unloading the DLL. During a hunt for memory leaks in an application a developer might want to free all memory allocated by Python before exiting from the application.
Bugs and caveats: The destruction of modules and objects in modules is
done in arbitrary order; this may cause destructors (del()
methods)
to fail when they depend on other objects (even functions) or modules.
Dynamically loaded extension modules loaded by Python are not unloaded.
Small amounts of memory allocated by the Python interpreter may not be
freed (if you find a leak, please report it). Memory tied up in circular
references between objects is not freed. Some memory allocated by extension
modules may not be freed. Some extensions may not work properly if their
initialization routine is called more than once; this can happen if an
application calls initialize
and finalize
more than once.
newInterpreter :: IO (Maybe ThreadState) Source #
Create a new sub-interpreter. This is an (almost) totally separate
environment for the execution of Python code. In particular, the new
interpreter has separate, independent versions of all imported modules,
including the fundamental modules builtins
, main
and sys
. The
table of loaded modules (sys.modules
) and the module search path
(sys.path
) are also separate. The new environment has no sys.argv
variable. It has new standard I/O stream file objects sys.stdin
,
sys.stdout
and sys.stderr
(however these refer to the same underlying
FILE
structures in the C library).
The return value points to the first thread state created in the new
sub-interpreter. This thread state is made in the current thread state.
Note that no actual thread is created; see the discussion of thread states
below. If creation of the new interpreter is unsuccessful, Nothing
is
returned; no exception is set since the exception state is stored in the
current thread state and there may not be a current thread state. (Like
all other Python/C API computations, the global interpreter lock must be
held before calling this computation and is still held when it returns;
however, unlike most other Python/C API computations, there
needn’t be a current thread state on entry.)
Extension modules are shared between (sub-)interpreters as follows: the
first time a particular extension is imported, it is initialized normally,
and a (shallow) copy of its module’s dictionary is squirreled away.
When the same extension is imported by another (sub-)interpreter, a new
module is initialized and filled with the contents of this copy; the
extension’s init
procedure is not called. Note that this is
different from what happens when an extension is imported after the
interpreter has been completely re-initialized by calling finalize
and
initialize
; in that case, the extension’s initmodule
procedure is called again.
Bugs and caveats: Because sub-interpreters (and the main interpreter)
are part of the same process, the insulation between them isn’t
perfect — for example, using low-level file operations like
os.close()
they can (accidentally or maliciously) affect each
other’s open files. Because of the way extensions are shared
between (sub-)interpreters, some extensions may not work properly; this
is especially likely when the extension makes use of (static) global
variables, or when the extension manipulates its module’s
dictionary after its initialization. It is possible to insert objects
created in one sub-interpreter into a namespace of another
sub-interpreter; this should be done with great care to avoid sharing
user-defined functions, methods, instances or classes between
sub-interpreters, since import operations executed by such objects may
affect the wrong (sub-)interpreter’s dictionary of loaded modules.
(XXX This is a hard-to-fix bug that will be addressed in a future release.)
Also note that the use of this functionality is incompatible with
extension modules such as PyObjC and ctypes that use the PyGILState_*()
APIs (and this is inherent in the way the PyGILState_*()
procedures
work). Simple things may work, but confusing behavior will always be near.
endInterpreter :: ThreadState -> IO () Source #
Destroy the (sub-)interpreter represented by the given thread state.
The given thread state must be the current thread state. See the
discussion of thread states below. When the call returns, the current
thread state is NULL
. All thread states associated with this
interpreter are destroyed. (The global interpreter lock must be held
before calling this computation and is still held when it returns.)
finalize
will destroy all sub-interpreters that haven’t been
explicitly destroyed at that point.
getProgramName :: IO Text Source #
Return the program name set with setProgramName
, or the default.
setProgramName :: Text -> IO () Source #
This computation should be called before initialize
is called for the
first time, if it is called at all. It tells the interpreter the value of
the argv[0]
argument to the main
procedure of the program. This is
used by getPath
and some other computations below to find the Python
run-time libraries relative to the interpreter executable. The default
value is "python"
. No code in the Python interpreter will change the
program name.
Return the prefix for installed platform-independent files. This is
derived through a number of complicated rules from the program name set
with setProgramName
and some environment variables; for example, if the
program name is "/usr/local/bin/python"
, the prefix is
"/usr/local"
. This corresponds to the prefix
variable in the
top-level Makefile and the --prefix argument to the configure
script
at build time. The value is available to Python code as sys.prefix
. It
is only useful on UNIX. See also getExecPrefix
.
getExecPrefix :: IO Text Source #
Return the exec-prefix for installed platform-dependent files. This
is derived through a number of complicated rules from the program name
set with setProgramName' and some environment variables; for example, if
the program name is "/usr/local/bin/python"
, the exec-prefix is
"/usr/local"
. This corresponds to the exec_prefix
variable in the
top-level Makefile and the --exec-prefix argument to the configure
script at build time. The value is available to Python code as
sys.exec_prefix
. It is only useful on UNIX.
Background: The exec-prefix differs from the prefix when platform
dependent files (such as executables and shared libraries) are installed
in a different directory tree. In a typical installation, platform
dependent files may be installed in the /usr/local/plat
subtree while
platform independent may be installed in /usr/local
.
Generally speaking, a platform is a combination of hardware and software families, e.g. Sparc machines running the Solaris 2.x operating system are considered the same platform, but Intel machines running Solaris 2.x are another platform, and Intel machines running Linux are yet another platform. Different major revisions of the same operating system generally also form different platforms. Non-UNIX operating systems are a different story; the installation strategies on those systems are so different that the prefix and exec-prefix are meaningless, and set to the empty string. Note that compiled Python bytecode files are platform independent (but not independent from the Python version by which they were compiled!).
System administrators will know how to configure the mount
or automount
programs to share /usr/local
between platforms while having
/usr/local/plat
be a different filesystem for each platform.
getProgramFullPath :: IO Text Source #
Return the full program name of the Python executable; this is computed
as a side-effect of deriving the default module search path from the
program name (set by setProgramName
above). The value is available to
Python code as sys.executable
.
Return the default module search path; this is computed from the
program name (set by setProgramName
above) and some environment
variables. The returned string consists of a series of directory names
separated by a platform dependent delimiter character. The delimiter
character is ':'
on Unix and Mac OS X, ';'
on Windows. The value
is available to Python code as the list sys.path
, which may be modified
to change the future search path for loaded modules.
getVersion :: IO Text Source #
Return the version of this Python interpreter. This is a string that looks something like
"3.0a5+ (py3k:63103M, May 12 2008, 00:53:55) \n[GCC 4.2.3]"
The first word (up to the first space character) is the current Python
version; the first three characters are the major and minor version
separated by a period. The value is available to Python code as
sys.version
.
getPlatform :: IO Text Source #
Return the platform identifier for the current platform. On Unix, this
is formed from the “official” name of the operating system,
converted to lower case, followed by the major revision number; e.g., for
Solaris 2.x, which is also known as SunOS 5.x, the value is "sunos5"
.
On Mac OS X, it is "darwin"
. On Windows, it is "win"
. The value
is available to Python code as sys.platform
.
getCopyright :: IO Text Source #
Return the official copyright string for the current Python version, for example
"Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam"
The value is available to Python code as sys.copyright
.
getCompiler :: IO Text Source #
Return an indication of the compiler used to build the current Python version, in square brackets, for example:
"[GCC 2.7.2.2]"
The value is available to Python code as part of the variable
sys.version
.
getBuildInfo :: IO Text Source #
Return information about the sequence number and build date and time of the current Python interpreter instance, for example
"#67, Aug 1 1997, 22:34:28"
The value is available to Python code as part of the variable
sys.version
.
setArgv :: Text -> [Text] -> IO () Source #
Set sys.argv
. The first parameter is similar to the result of
getProgName
, with the difference that it should refer to the script
file to be executed rather than the executable hosting the Python
interpreter. If there isn’t a script that will be run, the first
parameter can be an empty string. If this function fails to initialize
sys.argv
, a fatal condition is signalled using Py_FatalError()
.
This function also prepends the executed script’s path to
sys.path
. If no script is executed (in the case of calling python -c
or just the interactive interpreter), the empty string is used instead.
getPythonHome :: IO (Maybe Text) Source #
Return the default “home”, that is, the value set by a
previous call to setPythonHome
, or the value of the PYTHONHOME
environment variable if it is set.
setPythonHome :: Maybe Text -> IO () Source #
Set the default “home” directory, that is, the location
of the standard Python libraries. The libraries are searched in
home/lib/python version
and home/lib/python version
. No
code in the Python interpreter will change the Python home.