between versions of Python. Use of this module should not be considered to
work across Python VMs or Python releases.
+
Example: Given the function :func:`myfunc`::
def myfunc(alist):
.. function:: dis(x=None)
- Disassemble the *x* object. *x* can denote either a module, a
- class, a method, a function, or a code object. For a module, it disassembles
- all functions. For a class, it disassembles all methods. For a single code
- sequence, it prints one line per bytecode instruction. If no object is
- provided, it disassembles the last traceback.
+ Disassemble the *x* object. *x* can denote either a module, a
+ class, a method, a function, a code object, a string of source code or a
+ byte sequence of raw bytecode. For a module, it disassembles all
+ functions. For a class, it disassembles all methods. For a code object
+ or sequence of raw bytecode, it prints one line per bytecode instruction.
+ Strings are first compiled to code objects with the :func:`compile`
+ built-in function before being disassembled. If no object is provided,
+ this function disassembles the last traceback.
.. function:: distb(tb=None)
- Disassembles the top-of-stack function of a traceback, using the last traceback
- if none was passed. The instruction causing the exception is indicated.
+ Disassemble the top-of-stack function of a traceback, using the last
+ traceback if none was passed. The instruction causing the exception is
+ indicated.
.. function:: disassemble(code, lasti=-1)
disco(code, lasti=-1)
- Disassembles a code object, indicating the last instruction if *lasti* was
+ Disassemble a code object, indicating the last instruction if *lasti* was
provided. The output is divided in the following columns:
#. the line number, for the first instruction of each line
The Python compiler currently generates the following bytecode instructions.
-.. opcode:: STOP_CODE ()
+**General instructions**
+
+.. opcode:: STOP_CODE
Indicates end-of-code to the compiler, not used by the interpreter.
-.. opcode:: NOP ()
+.. opcode:: NOP
Do nothing code. Used as a placeholder by the bytecode optimizer.
-.. opcode:: POP_TOP ()
+.. opcode:: POP_TOP
Removes the top-of-stack (TOS) item.
-.. opcode:: ROT_TWO ()
+.. opcode:: ROT_TWO
Swaps the two top-most stack items.
-.. opcode:: ROT_THREE ()
+.. opcode:: ROT_THREE
Lifts second and third stack item one position up, moves top down to position
three.
-.. opcode:: ROT_FOUR ()
+.. opcode:: ROT_FOUR
Lifts second, third and forth stack item one position up, moves top down to
position four.
-.. opcode:: DUP_TOP ()
+.. opcode:: DUP_TOP
Duplicates the reference on top of the stack.
-Unary Operations take the top of the stack, apply the operation, and push the
-result back on the stack.
+**Unary operations**
-.. opcode:: UNARY_POSITIVE ()
+Unary operations take the top of the stack, apply the operation, and push the
+result back on the stack.
+
+.. opcode:: UNARY_POSITIVE
Implements ``TOS = +TOS``.
-.. opcode:: UNARY_NEGATIVE ()
+.. opcode:: UNARY_NEGATIVE
Implements ``TOS = -TOS``.
-.. opcode:: UNARY_NOT ()
+.. opcode:: UNARY_NOT
Implements ``TOS = not TOS``.
-.. opcode:: UNARY_INVERT ()
+.. opcode:: UNARY_INVERT
Implements ``TOS = ~TOS``.
-.. opcode:: GET_ITER ()
+.. opcode:: GET_ITER
Implements ``TOS = iter(TOS)``.
+
+**Binary operations**
+
Binary operations remove the top of the stack (TOS) and the second top-most
stack item (TOS1) from the stack. They perform the operation, and put the
result back on the stack.
-
-.. opcode:: BINARY_POWER ()
+.. opcode:: BINARY_POWER
Implements ``TOS = TOS1 ** TOS``.
-.. opcode:: BINARY_MULTIPLY ()
+.. opcode:: BINARY_MULTIPLY
Implements ``TOS = TOS1 * TOS``.
-.. opcode:: BINARY_FLOOR_DIVIDE ()
+.. opcode:: BINARY_FLOOR_DIVIDE
Implements ``TOS = TOS1 // TOS``.
-.. opcode:: BINARY_TRUE_DIVIDE ()
+.. opcode:: BINARY_TRUE_DIVIDE
Implements ``TOS = TOS1 / TOS``.
-.. opcode:: BINARY_MODULO ()
+.. opcode:: BINARY_MODULO
Implements ``TOS = TOS1 % TOS``.
-.. opcode:: BINARY_ADD ()
+.. opcode:: BINARY_ADD
Implements ``TOS = TOS1 + TOS``.
-.. opcode:: BINARY_SUBTRACT ()
+.. opcode:: BINARY_SUBTRACT
Implements ``TOS = TOS1 - TOS``.
-.. opcode:: BINARY_SUBSCR ()
+.. opcode:: BINARY_SUBSCR
Implements ``TOS = TOS1[TOS]``.
-.. opcode:: BINARY_LSHIFT ()
+.. opcode:: BINARY_LSHIFT
Implements ``TOS = TOS1 << TOS``.
-.. opcode:: BINARY_RSHIFT ()
+.. opcode:: BINARY_RSHIFT
Implements ``TOS = TOS1 >> TOS``.
-.. opcode:: BINARY_AND ()
+.. opcode:: BINARY_AND
Implements ``TOS = TOS1 & TOS``.
-.. opcode:: BINARY_XOR ()
+.. opcode:: BINARY_XOR
Implements ``TOS = TOS1 ^ TOS``.
-.. opcode:: BINARY_OR ()
+.. opcode:: BINARY_OR
Implements ``TOS = TOS1 | TOS``.
+
+**In-place operations**
+
In-place operations are like binary operations, in that they remove TOS and
TOS1, and push the result back on the stack, but the operation is done in-place
when TOS1 supports it, and the resulting TOS may be (but does not have to be)
the original TOS1.
-
-.. opcode:: INPLACE_POWER ()
+.. opcode:: INPLACE_POWER
Implements in-place ``TOS = TOS1 ** TOS``.
-.. opcode:: INPLACE_MULTIPLY ()
+.. opcode:: INPLACE_MULTIPLY
Implements in-place ``TOS = TOS1 * TOS``.
-.. opcode:: INPLACE_FLOOR_DIVIDE ()
+.. opcode:: INPLACE_FLOOR_DIVIDE
Implements in-place ``TOS = TOS1 // TOS``.
-.. opcode:: INPLACE_TRUE_DIVIDE ()
+.. opcode:: INPLACE_TRUE_DIVIDE
Implements in-place ``TOS = TOS1 / TOS``.
-.. opcode:: INPLACE_MODULO ()
+.. opcode:: INPLACE_MODULO
Implements in-place ``TOS = TOS1 % TOS``.
-.. opcode:: INPLACE_ADD ()
+.. opcode:: INPLACE_ADD
Implements in-place ``TOS = TOS1 + TOS``.
-.. opcode:: INPLACE_SUBTRACT ()
+.. opcode:: INPLACE_SUBTRACT
Implements in-place ``TOS = TOS1 - TOS``.
-.. opcode:: INPLACE_LSHIFT ()
+.. opcode:: INPLACE_LSHIFT
Implements in-place ``TOS = TOS1 << TOS``.
-.. opcode:: INPLACE_RSHIFT ()
+.. opcode:: INPLACE_RSHIFT
Implements in-place ``TOS = TOS1 >> TOS``.
-.. opcode:: INPLACE_AND ()
+.. opcode:: INPLACE_AND
Implements in-place ``TOS = TOS1 & TOS``.
-.. opcode:: INPLACE_XOR ()
+.. opcode:: INPLACE_XOR
Implements in-place ``TOS = TOS1 ^ TOS``.
-.. opcode:: INPLACE_OR ()
+.. opcode:: INPLACE_OR
Implements in-place ``TOS = TOS1 | TOS``.
-.. opcode:: STORE_SUBSCR ()
+.. opcode:: STORE_SUBSCR
Implements ``TOS1[TOS] = TOS2``.
-.. opcode:: DELETE_SUBSCR ()
+.. opcode:: DELETE_SUBSCR
Implements ``del TOS1[TOS]``.
-Miscellaneous opcodes.
+**Miscellaneous opcodes**
-.. opcode:: PRINT_EXPR ()
+.. opcode:: PRINT_EXPR
Implements the expression statement for the interactive mode. TOS is removed
from the stack and printed. In non-interactive mode, an expression statement is
terminated with ``POP_STACK``.
-.. opcode:: BREAK_LOOP ()
+.. opcode:: BREAK_LOOP
Terminates a loop due to a :keyword:`break` statement.
Calls ``dict.setitem(TOS1[-i], TOS, TOS1)``. Used to implement dict
comprehensions.
-
For all of the SET_ADD, LIST_APPEND and MAP_ADD instructions, while the
added value or key/value pair is popped off, the container object remains on
the stack so that it is available for further iterations of the loop.
-.. opcode:: RETURN_VALUE ()
+.. opcode:: RETURN_VALUE
Returns with TOS to the caller of the function.
-.. opcode:: YIELD_VALUE ()
+.. opcode:: YIELD_VALUE
Pops ``TOS`` and yields it from a :term:`generator`.
-.. opcode:: IMPORT_STAR ()
+.. opcode:: IMPORT_STAR
Loads all symbols not starting with ``'_'`` directly from the module TOS to the
local namespace. The module is popped after loading all names. This opcode
implements ``from module import *``.
-.. opcode:: POP_BLOCK ()
+.. opcode:: POP_BLOCK
Removes one block from the block stack. Per frame, there is a stack of blocks,
denoting nested loops, try statements, and such.
-.. opcode:: POP_EXCEPT ()
+.. opcode:: POP_EXCEPT
Removes one block from the block stack. The popped block must be an exception
handler block, as implicitly created when entering an except handler.
last three popped values are used to restore the exception state.
-.. opcode:: END_FINALLY ()
+.. opcode:: END_FINALLY
Terminates a :keyword:`finally` clause. The interpreter recalls whether the
exception has to be re-raised, or whether the function returns, and continues
with the outer-next block.
-.. opcode:: LOAD_BUILD_CLASS ()
+.. opcode:: LOAD_BUILD_CLASS
Pushes :func:`builtins.__build_class__` onto the stack. It is later called
by ``CALL_FUNCTION`` to construct a class.
-.. opcode:: WITH_CLEANUP ()
+.. opcode:: WITH_CLEANUP
Cleans up the stack when a :keyword:`with` statement block exits. TOS is
the context manager's :meth:`__exit__` bound method. Below TOS are 1--3
Pushes a try block from a try-except clause onto the block stack. *delta* points
to the finally block.
-.. opcode:: STORE_MAP ()
+.. opcode:: STORE_MAP
Store a key and value pair in a dictionary. Pops the key and value while leaving
the dictionary on the stack.
variable-arguments tuple, followed by explicit keyword and positional arguments.
-.. opcode:: HAVE_ARGUMENT ()
+.. opcode:: HAVE_ARGUMENT
This is not really an opcode. It identifies the dividing line between opcodes
which don't take arguments ``< HAVE_ARGUMENT`` and those which do ``>=