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This module has no docstring.
with_traceback(...)
Exception.with_traceback(tb) --
set self.__traceback__ to tb and return self.
args = <attribute 'args' of 'BaseException' objects>
The main top-level class that you instantiate once, or once per module.
Example usage:
ffi = FFI()
ffi.cdef("""
int printf(const char *, ...);
""")
C = ffi.dlopen(None) # standard library
-or-
C = ffi.verify() # use a C compiler: verify the decl above is right
C.printf("hello, %s!\n", ffi.new("char[]", "world"))
addressof(self, cdata, *fields_or_indexes)
Return the address of a <cdata 'struct-or-union'>.
If 'fields_or_indexes' are given, returns the address of that
field or array item in the structure or array, recursively in
case of nested structures.
alignof(self, cdecl)
Return the natural alignment size in bytes of the C type
given as a string.
callback(self, cdecl, python_callable=None, error=None, onerror=None)
Return a callback object or a decorator making such a
callback object. 'cdecl' must name a C function pointer type.
The callback invokes the specified 'python_callable' (which may
be provided either directly or via a decorator). Important: the
callback object must be manually kept alive for as long as the
callback may be invoked from the C level.
cast(self, cdecl, source)
Similar to a C cast: returns an instance of the named C
type initialized with the given 'source'. The source is
casted between integers or pointers of any type.
cdef(self, csource, override=False, packed=False, pack=None)
Parse the given C source. This registers all declared functions,
types, and global variables. The functions and global variables can
then be accessed via either 'ffi.dlopen()' or 'ffi.verify()'.
The types can be used in 'ffi.new()' and other functions.
If 'packed' is specified as True, all structs declared inside this
cdef are packed, i.e. laid out without any field alignment at all.
Alternatively, 'pack' can be a small integer, and requests for
alignment greater than that are ignored (pack=1 is equivalent to
packed=True).
compile(self, tmpdir='.', verbose=0, target=None, debug=None)
The 'target' argument gives the final file name of the
compiled DLL. Use '*' to force distutils' choice, suitable for
regular CPython C API modules. Use a file name ending in '.*'
to ask for the system's default extension for dynamic libraries
(.so/.dll/.dylib).
The default is '*' when building a non-embedded C API extension,
and (module_name + '.*') when building an embedded library.
def_extern(self, *args, **kwds)
distutils_extension(self, tmpdir='build', verbose=True)
dlclose(self, lib)
Close a library obtained with ffi.dlopen(). After this call,
access to functions or variables from the library will fail
(possibly with a segmentation fault).
dlopen(self, name, flags=0)
Load and return a dynamic library identified by 'name'.
The standard C library can be loaded by passing None.
Note that functions and types declared by 'ffi.cdef()' are not
linked to a particular library, just like C headers; in the
library we only look for the actual (untyped) symbols.
embedding_api(self, csource, packed=False, pack=None)
embedding_init_code(self, pysource)
emit_c_code(self, filename)
emit_python_code(self, filename)
from_buffer(self, cdecl, python_buffer=<object object at 0x7f75e3c96870>, require_writable=False)
Return a cdata of the given type pointing to the data of the
given Python object, which must support the buffer interface.
Note that this is not meant to be used on the built-in types
str or unicode (you can build 'char[]' arrays explicitly)
but only on objects containing large quantities of raw data
in some other format, like 'array.array' or numpy arrays.
The first argument is optional and default to 'char[]'.
from_handle(self, x)
gc(self, cdata, destructor, size=0)
Return a new cdata object that points to the same
data. Later, when this new cdata object is garbage-collected,
'destructor(old_cdata_object)' will be called.
The optional 'size' gives an estimate of the size, used to
trigger the garbage collection more eagerly. So far only used
on PyPy. It tells the GC that the returned object keeps alive
roughly 'size' bytes of external memory.
getctype(self, cdecl, replace_with='')
Return a string giving the C type 'cdecl', which may be itself
a string or a <ctype> object. If 'replace_with' is given, it gives
extra text to append (or insert for more complicated C types), like
a variable name, or '*' to get actually the C type 'pointer-to-cdecl'.
getwinerror(self, code=-1)
include(self, ffi_to_include)
Includes the typedefs, structs, unions and enums defined
in another FFI instance. Usage is similar to a #include in C,
where a part of the program might include types defined in
another part for its own usage. Note that the include()
method has no effect on functions, constants and global
variables, which must anyway be accessed directly from the
lib object returned by the original FFI instance.
init_once(self, func, tag)
list_types(self)
Returns the user type names known to this FFI instance.
This returns a tuple containing three lists of names:
(typedef_names, names_of_structs, names_of_unions)
memmove(self, dest, src, n)
ffi.memmove(dest, src, n) copies n bytes of memory from src to dest.
Like the C function memmove(), the memory areas may overlap;
apart from that it behaves like the C function memcpy().
'src' can be any cdata ptr or array, or any Python buffer object.
'dest' can be any cdata ptr or array, or a writable Python buffer
object. The size to copy, 'n', is always measured in bytes.
Unlike other methods, this one supports all Python buffer including
byte strings and bytearrays---but it still does not support
non-contiguous buffers.
new(self, cdecl, init=None)
Allocate an instance according to the specified C type and
return a pointer to it. The specified C type must be either a
pointer or an array: ``new('X *')`` allocates an X and returns
a pointer to it, whereas ``new('X[n]')`` allocates an array of
n X'es and returns an array referencing it (which works
mostly like a pointer, like in C). You can also use
``new('X[]', n)`` to allocate an array of a non-constant
length n.
The memory is initialized following the rules of declaring a
global variable in C: by default it is zero-initialized, but
an explicit initializer can be given which can be used to
fill all or part of the memory.
When the returned <cdata> object goes out of scope, the memory
is freed. In other words the returned <cdata> object has
ownership of the value of type 'cdecl' that it points to. This
means that the raw data can be used as long as this object is
kept alive, but must not be used for a longer time. Be careful
about that when copying the pointer to the memory somewhere
else, e.g. into another structure.
new_allocator(self, alloc=None, free=None, should_clear_after_alloc=True)
Return a new allocator, i.e. a function that behaves like ffi.new()
but uses the provided low-level 'alloc' and 'free' functions.
'alloc' is called with the size as argument. If it returns NULL, a
MemoryError is raised. 'free' is called with the result of 'alloc'
as argument. Both can be either Python function or directly C
functions. If 'free' is None, then no free function is called.
If both 'alloc' and 'free' are None, the default is used.
If 'should_clear_after_alloc' is set to False, then the memory
returned by 'alloc' is assumed to be already cleared (or you are
fine with garbage); otherwise CFFI will clear it.
new_handle(self, x)
offsetof(self, cdecl, *fields_or_indexes)
Return the offset of the named field inside the given
structure or array, which must be given as a C type name.
You can give several field names in case of nested structures.
You can also give numeric values which correspond to array
items, in case of an array type.
release(self, x)
set_source(self, module_name, source, source_extension='.c', **kwds)
set_source_pkgconfig(self, module_name, pkgconfig_libs, source, source_extension='.c', **kwds)
set_unicode(self, enabled_flag)
Windows: if 'enabled_flag' is True, enable the UNICODE and
_UNICODE defines in C, and declare the types like TCHAR and LPTCSTR
to be (pointers to) wchar_t. If 'enabled_flag' is False,
declare these types to be (pointers to) plain 8-bit characters.
This is mostly for backward compatibility; you usually want True.
sizeof(self, cdecl)
Return the size in bytes of the argument. It can be a
string naming a C type, or a 'cdata' instance.
string(self, cdata, maxlen=-1)
Return a Python string (or unicode string) from the 'cdata'.
If 'cdata' is a pointer or array of characters or bytes, returns
the null-terminated string. The returned string extends until
the first null character, or at most 'maxlen' characters. If
'cdata' is an array then 'maxlen' defaults to its length.
If 'cdata' is a pointer or array of wchar_t, returns a unicode
string following the same rules.
If 'cdata' is a single character or byte or a wchar_t, returns
it as a string or unicode string.
If 'cdata' is an enum, returns the value of the enumerator as a
string, or 'NUMBER' if the value is out of range.
typeof(self, cdecl)
Parse the C type given as a string and return the
corresponding <ctype> object.
It can also be used on 'cdata' instance to get its C type.
unpack(self, cdata, length)
Unpack an array of C data of the given length,
returning a Python string/unicode/list.
If 'cdata' is a pointer to 'char', returns a byte string.
It does not stop at the first null. This is equivalent to:
ffi.buffer(cdata, length)[:]
If 'cdata' is a pointer to 'wchar_t', returns a unicode string.
'length' is measured in wchar_t's; it is not the size in bytes.
If 'cdata' is a pointer to anything else, returns a list of
'length' items. This is a faster equivalent to:
[cdata[i] for i in range(length)]
verify(self, source='', tmpdir=None, **kwargs)
Verify that the current ffi signatures compile on this
machine, and return a dynamic library object. The dynamic
library can be used to call functions and access global
variables declared in this 'ffi'. The library is compiled
by the C compiler: it gives you C-level API compatibility
(including calling macros). This is unlike 'ffi.dlopen()',
which requires binary compatibility in the signatures.
errno = <property object at 0x7f75e070bd30> the value of 'errno' from/to the C calls
with_traceback(...)
Exception.with_traceback(tb) --
set self.__traceback__ to tb and return self.
args = <attribute 'args' of 'BaseException' objects>
An error raised for missing modules in pkg-config
with_traceback(...)
Exception.with_traceback(tb) --
set self.__traceback__ to tb and return self.
args = <attribute 'args' of 'BaseException' objects>
An error raised when verification fails
with_traceback(...)
Exception.with_traceback(tb) --
set self.__traceback__ to tb and return self.
args = <attribute 'args' of 'BaseException' objects>
An error raised when incomplete structures are passed into
cdef, but no verification has been done
with_traceback(...)
Exception.with_traceback(tb) --
set self.__traceback__ to tb and return self.
args = <attribute 'args' of 'BaseException' objects>