org.python.core

Class BytecodeLoader

java.lang.Object

org.python.core.BytecodeLoader

public class BytecodeLoader
extends java.lang.Object

Utility class for loading compiled Python modules and Java classes defined in Python modules.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	BytecodeLoader.Loader

Constructor Summary

Constructors

Constructor and Description
BytecodeLoader()

Method Summary

Modifier and Type	Method and Description
static void	fixPyBytecode(java.lang.Class<? extends ContainsPyBytecode> c) This method looks for Python bytecode stored in string literals.
static boolean	getIgnoreSerialVersionUID() Only relevant in presence of oversized methods or functions, this tells whether or not to ignore serialVersionUID associated with the corresponding code objects.
static java.lang.Class<?>	makeClass(java.lang.String name, byte[] data, java.lang.Class<?>... referents) Turn the Java class file data into a Java class.
static java.lang.Class<?>	makeClass(java.lang.String name, java.util.List<java.lang.Class<?>> referents, byte[] data) Turn the Java class file data into a Java class.
static PyCode	makeCode(java.lang.String name, byte[] data, java.lang.String filename) Turn the Java class file data for a compiled Python module into a PyCode object, by constructing an instance of the named class and calling the instance's PyRunnable.getMain().
static void	setIgnoreSerialVersionUID(boolean value) Only relevant in presence of oversized methods or functions, this controls whether or not to ignore serialVersionUID associated with the corresponding code objects.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BytecodeLoader

public BytecodeLoader()

Method Detail

getIgnoreSerialVersionUID

public static boolean getIgnoreSerialVersionUID()

Only relevant in presence of oversized methods or functions, this tells whether or not to ignore serialVersionUID associated with the corresponding code objects. Default value is true. See setIgnoreSerialVersionUID(boolean) for details.

Returns:

whether or not serialVersionUID data is ignored when PyBytecode objects are parsed via Java serialization in fixPyBytecode(Class), default is true

See Also:

setIgnoreSerialVersionUID(boolean), fixPyBytecode(Class)

setIgnoreSerialVersionUID

public static void setIgnoreSerialVersionUID(boolean value)

Only relevant in presence of oversized methods or functions, this controls whether or not to ignore serialVersionUID associated with the corresponding code objects. Methods and functions in Python might not be compilable to JVM bytecode if they exceed a certain size. In that case, Jython can use compiled CPython bytecode (as in .pyc files) instead. This bytecode is embedded into the module's $py.class file by storing the PyBytecode object via Java serialization in string constants. This mechanism can break compatibility with older Jython versions if computed values of serialVersionUID changed due to subtle code adjustments. Usually, compatibility is not actually broken, so Jython bypasses the check for serialVersionUID as far as objects comprised by a PyBytecode object are concerned. This option allows to control that behavior. By setting it to false, a strict check for serialVersionUID is required. By default, the value of this option is true and the check is bypassed.

Parameters:

value - indicates whether or not serialVersionUID data is to be ignored when PyBytecode objects are parsed via Java serialization in fixPyBytecode(Class), default is true.

See Also:

getIgnoreSerialVersionUID(), fixPyBytecode(Class), Solve serialization backward incompatibility of oversized methods and functions., Clarification on compile (Module or method too large)

makeClass

public static java.lang.Class<?> makeClass(java.lang.String name,
                                           byte[] data,
                                           java.lang.Class<?>... referents)

Turn the Java class file data into a Java class.

Parameters:

name - fully-qualified binary name of the class

data - a class file as a byte array

referents - super-classes and interfaces that the new class will reference.

makeClass

public static java.lang.Class<?> makeClass(java.lang.String name,
                                           java.util.List<java.lang.Class<?>> referents,
                                           byte[] data)

Turn the Java class file data into a Java class.

Parameters:

name - the name of the class

referents - super-classes and interfaces that the new class will reference.

data - a class file as a byte array

fixPyBytecode

public static void fixPyBytecode(java.lang.Class<? extends ContainsPyBytecode> c)
                          throws java.lang.IllegalAccessException,
                                 java.lang.NoSuchFieldException,
                                 java.io.IOException,
                                 java.lang.ClassNotFoundException

This method looks for Python bytecode stored in string literals. While Java supports rather long strings, constrained only by int-addressing of arrays, it supports only up to 65535 characters in literals (not sure how escape-sequences are counted). To circumvent this limitation, the code is automatically split into several literals with the following naming-scheme.

The marker-interface ContainsPyBytecode indicates that a class contains (static final) literals of the following scheme:

• a prefix of '___' indicates a bytecode-containing string literal
• a number indicating the number of parts follows
• '0_' indicates that no splitting occurred
• otherwise another number follows, naming the index of the literal
• indexing starts at 0

Examples:

• ___0_method1 contains bytecode for method1
• ___2_0_method2 contains first part of method2's bytecode
• ___2_1_method2 contains second part of method2's bytecode

Note that this approach is provisional. In future, Jython might contain the bytecode directly as bytecode objects. The current approach was feasible with much less complicated JVM bytecode manipulation, but needs special treatment after class loading.

Throws:

java.lang.IllegalAccessException

java.lang.NoSuchFieldException

java.io.IOException

java.lang.ClassNotFoundException

See Also:

ContainsPyBytecode

makeCode

public static PyCode makeCode(java.lang.String name,
                              byte[] data,
                              java.lang.String filename)

Turn the Java class file data for a compiled Python module into a PyCode object, by constructing an instance of the named class and calling the instance's PyRunnable.getMain().

Parameters:

name - fully-qualified binary name of the class

data - a class file as a byte array

filename - to provide to the constructor of the named class

Returns:

the PyCode object produced by the named class' getMain