A tool for inspecting Python pickles¶
AUTHORS:
- Carl Witty (2009-03) 
The explain_pickle() function takes a pickle and produces Sage code that
will evaluate to the contents of the pickle.  Ideally, the combination
of explain_pickle() to produce Sage code and sage_eval() to evaluate the code
would be a 100% compatible implementation of cPickle’s unpickler; this
is almost the case now.
EXAMPLES:
sage: explain_pickle(dumps(12345))
pg_make_integer = unpickle_global('sage.rings.integer', 'make_integer')
pg_make_integer('c1p')
sage: explain_pickle(dumps(polygen(QQ)))
pg_Polynomial_rational_flint = unpickle_global('sage.rings.polynomial.polynomial_rational_flint', 'Polynomial_rational_flint')
pg_unpickle_PolynomialRing = unpickle_global('sage.rings.polynomial.polynomial_ring_constructor', 'unpickle_PolynomialRing')
pg_RationalField = unpickle_global('sage.rings.rational_field', 'RationalField')
pg = unpickle_instantiate(pg_RationalField, ())
pg_make_rational = unpickle_global('sage.rings.rational', 'make_rational')
pg_Polynomial_rational_flint(pg_unpickle_PolynomialRing(pg, ('x',), None, False), [pg_make_rational('0'), pg_make_rational('1')], False, True)
sage: sage_eval(explain_pickle(dumps(polygen(QQ)))) == polygen(QQ)
True
>>> from sage.all import *
>>> explain_pickle(dumps(Integer(12345)))
pg_make_integer = unpickle_global('sage.rings.integer', 'make_integer')
pg_make_integer('c1p')
>>> explain_pickle(dumps(polygen(QQ)))
pg_Polynomial_rational_flint = unpickle_global('sage.rings.polynomial.polynomial_rational_flint', 'Polynomial_rational_flint')
pg_unpickle_PolynomialRing = unpickle_global('sage.rings.polynomial.polynomial_ring_constructor', 'unpickle_PolynomialRing')
pg_RationalField = unpickle_global('sage.rings.rational_field', 'RationalField')
pg = unpickle_instantiate(pg_RationalField, ())
pg_make_rational = unpickle_global('sage.rings.rational', 'make_rational')
pg_Polynomial_rational_flint(pg_unpickle_PolynomialRing(pg, ('x',), None, False), [pg_make_rational('0'), pg_make_rational('1')], False, True)
>>> sage_eval(explain_pickle(dumps(polygen(QQ)))) == polygen(QQ)
True
By default (as above) the code produced contains calls to several
utility functions (unpickle_global(), etc.); this is done so that the
code is truly equivalent to the pickle.  If the pickle can be loaded
into a future version of Sage, then the code that explain_pickle()
produces today should work in that future Sage as well.
It is also possible to produce simpler code, that is tied to the current version of Sage; here are the above two examples again:
sage: explain_pickle(dumps(12345), in_current_sage=True)
from sage.rings.integer import make_integer
make_integer('c1p')
sage: explain_pickle(dumps(polygen(QQ)), in_current_sage=True)
from sage.rings.polynomial.polynomial_rational_flint import Polynomial_rational_flint
from sage.rings.polynomial.polynomial_ring_constructor import unpickle_PolynomialRing
from sage.rings.rational import make_rational
Polynomial_rational_flint(unpickle_PolynomialRing(RationalField(), ('x',), None, False), [make_rational('0'), make_rational('1')], False, True)
>>> from sage.all import *
>>> explain_pickle(dumps(Integer(12345)), in_current_sage=True)
from sage.rings.integer import make_integer
make_integer('c1p')
>>> explain_pickle(dumps(polygen(QQ)), in_current_sage=True)
from sage.rings.polynomial.polynomial_rational_flint import Polynomial_rational_flint
from sage.rings.polynomial.polynomial_ring_constructor import unpickle_PolynomialRing
from sage.rings.rational import make_rational
Polynomial_rational_flint(unpickle_PolynomialRing(RationalField(), ('x',), None, False), [make_rational('0'), make_rational('1')], False, True)
The explain_pickle() function has several use cases.
Write pickling support for your classes
You can use
explain_pickle()to see what will happen when a pickle is unpickled. Consider: is this sequence of commands something that can be easily supported in all future Sage versions, or does it expose internal design decisions that are subject to change?
Debug old pickles
If you have a pickle from an old version of Sage that no longer unpickles, you can use
explain_pickle()to see what it is trying to do, to figure out how to fix it.
Use
explain_pickle()in doctests to help maintenanceIf you have a
loads(dumps(S))doctest, you could also add anexplain_pickle(dumps(S))doctest. Then if something changes in a way that would invalidate old pickles, the output ofexplain_pickle()will also change. At that point, you can add the previous output ofexplain_pickleas a new set of doctests (and then update theexplain_pickledoctest to use the new output), to ensure that old pickles will continue to work.
As mentioned above, there are several output modes for explain_pickle(),
that control fidelity versus simplicity of the output.  For example,
the GLOBAL instruction takes a module name and a class name and
produces the corresponding class.  So GLOBAL of sage.rings.integer,
Integer is approximately equivalent to sage.rings.integer.Integer.
However, this class lookup process can be customized (using
sage.misc.persist.register_unpickle_override()).  For instance,
if some future version of Sage renamed sage/rings/integer.pyx to
sage/rings/knuth_was_here.pyx, old pickles would no longer work unless
register_unpickle_override was used; in that case, GLOBAL of
sage.rings.integer, integer would mean
sage.rings.knuth_was_here.integer.
By default, explain_pickle() will map this GLOBAL instruction to
unpickle_global('sage.rings.integer', 'integer').  Then when this code
is evaluated, unpickle_global() will look up the current mapping in the
register_unpickle_override() table, so the generated code will continue
to work even in hypothetical future versions of Sage where integer.pyx
has been renamed.
If you pass the flag in_current_sage=True, then
explain_pickle() will generate code that may only work in the
current version of Sage, not in future versions.  In this case, it
would generate:
from sage.rings.integer import integer
and if you ran explain_pickle() in hypothetical future sage, it would generate:
from sage.rings.knuth_was_here import integer
but the current code wouldn’t work in the future sage.
If you pass the flag default_assumptions=True, then
explain_pickle() will generate code that would work in the
absence of any special unpickling information.  That is, in either
current Sage or hypothetical future Sage, it would generate:
from sage.rings.integer import integer
The intention is that default_assumptions output is prettier (more
human-readable), but may not actually work; so it is only intended for
human reading.
There are several functions used in the output of explain_pickle().
Here I give a brief description of what they usually do, as well as
how to modify their operation (for instance, if you’re trying to get
old pickles to work).
unpickle_global(module, classname):unpickle_global('sage.foo.bar', 'baz')is usually equivalent tosage.foo.bar.baz, but this can be customized withregister_unpickle_override().
unpickle_newobj(klass, args): Usually equivalent toklass.__new__(klass, *args). Ifklassis a Python class, then you can define__new__()to control the result (this result actually need not be an instance ofklass). (This doesn’t work for Cython classes.)
unpickle_build(obj, state): Ifobjhas a__setstate__()method, then this is equivalent toobj.__setstate__(state). Otherwise usesstateto set the attributes ofobj. Customize by defining__setstate__().
unpickle_instantiate(klass, args): Usually equivalent toklass(*args). Cannot be customized.
unpickle_appends(lst, vals): Appends the values invalstolst. If notisinstance(lst, list), can be customized by defining aappend()method.
- class sage.misc.explain_pickle.EmptyNewstyleClass[source]¶
- Bases: - object- A featureless new-style class (inherits from object); used for testing - explain_pickle().
- class sage.misc.explain_pickle.EmptyOldstyleClass[source]¶
- Bases: - object- A featureless old-style class (does not inherit from object); used for testing - explain_pickle().
- class sage.misc.explain_pickle.PickleDict(items)[source]¶
- Bases: - object- An object which can be used as the value of a - PickleObject. The items is a list of key-value pairs, where the keys and values are- SageInputExpressionobjects. We use this to help construct dictionary literals, instead of always starting with an empty dictionary and assigning to it.
- class sage.misc.explain_pickle.PickleExplainer(sib, in_current_sage=False, default_assumptions=False, pedantic=False)[source]¶
- Bases: - object- An interpreter for the pickle virtual machine, that executes symbolically and constructs - SageInputExpressionobjects instead of directly constructing values.- check_value(v)[source]¶
- Check that the given value is either a - SageInputExpressionor a- PickleObject. Used for internal sanity checking.- EXAMPLES: - sage: from sage.misc.explain_pickle import * sage: from sage.misc.sage_input import SageInputBuilder sage: sib = SageInputBuilder() sage: pe = PickleExplainer(sib, in_current_sage=True, default_assumptions=False, pedantic=True) sage: pe.check_value(7) Traceback (most recent call last): ... AssertionError sage: pe.check_value(sib(7)) - >>> from sage.all import * >>> from sage.misc.explain_pickle import * >>> from sage.misc.sage_input import SageInputBuilder >>> sib = SageInputBuilder() >>> pe = PickleExplainer(sib, in_current_sage=True, default_assumptions=False, pedantic=True) >>> pe.check_value(Integer(7)) Traceback (most recent call last): ... AssertionError >>> pe.check_value(sib(Integer(7))) 
 - is_mutable_pickle_object(v)[source]¶
- Test whether a - PickleObjectis mutable (has never been converted to a- SageInputExpression).- EXAMPLES: - sage: from sage.misc.explain_pickle import * sage: from sage.misc.sage_input import SageInputBuilder sage: sib = SageInputBuilder() sage: pe = PickleExplainer(sib, in_current_sage=True, ....: default_assumptions=False, pedantic=True) sage: v = PickleObject(1, sib(1)) sage: pe.is_mutable_pickle_object(v) True sage: sib(v) {atomic:1} sage: pe.is_mutable_pickle_object(v) False - >>> from sage.all import * >>> from sage.misc.explain_pickle import * >>> from sage.misc.sage_input import SageInputBuilder >>> sib = SageInputBuilder() >>> pe = PickleExplainer(sib, in_current_sage=True, ... default_assumptions=False, pedantic=True) >>> v = PickleObject(Integer(1), sib(Integer(1))) >>> pe.is_mutable_pickle_object(v) True >>> sib(v) {atomic:1} >>> pe.is_mutable_pickle_object(v) False 
 - pop()[source]¶
- Pop a value from the virtual machine’s stack, and return it. - EXAMPLES: - sage: from sage.misc.explain_pickle import * sage: from sage.misc.sage_input import SageInputBuilder sage: sib = SageInputBuilder() sage: pe = PickleExplainer(sib, in_current_sage=True, default_assumptions=False, pedantic=True) sage: pe.push(sib(7)) sage: pe.pop() {atomic:7} - >>> from sage.all import * >>> from sage.misc.explain_pickle import * >>> from sage.misc.sage_input import SageInputBuilder >>> sib = SageInputBuilder() >>> pe = PickleExplainer(sib, in_current_sage=True, default_assumptions=False, pedantic=True) >>> pe.push(sib(Integer(7))) >>> pe.pop() {atomic:7} 
 - pop_to_mark()[source]¶
- Pop all values down to the ‘mark’ from the virtual machine’s stack, and return the values as a list. - EXAMPLES: - sage: from sage.misc.explain_pickle import * sage: from sage.misc.sage_input import SageInputBuilder sage: sib = SageInputBuilder() sage: pe = PickleExplainer(sib, in_current_sage=True, default_assumptions=False, pedantic=True) sage: pe.push_mark() sage: pe.push(sib(7)) sage: pe.push(sib('hello')) sage: pe.pop_to_mark() [{atomic:7}, {atomic:'hello'}] - >>> from sage.all import * >>> from sage.misc.explain_pickle import * >>> from sage.misc.sage_input import SageInputBuilder >>> sib = SageInputBuilder() >>> pe = PickleExplainer(sib, in_current_sage=True, default_assumptions=False, pedantic=True) >>> pe.push_mark() >>> pe.push(sib(Integer(7))) >>> pe.push(sib('hello')) >>> pe.pop_to_mark() [{atomic:7}, {atomic:'hello'}] 
 - push(v)[source]¶
- Push a value onto the virtual machine’s stack. - EXAMPLES: - sage: from sage.misc.explain_pickle import * sage: from sage.misc.sage_input import SageInputBuilder sage: sib = SageInputBuilder() sage: pe = PickleExplainer(sib, in_current_sage=True, default_assumptions=False, pedantic=True) sage: pe.push(sib(7)) sage: pe.stack[-1] {atomic:7} - >>> from sage.all import * >>> from sage.misc.explain_pickle import * >>> from sage.misc.sage_input import SageInputBuilder >>> sib = SageInputBuilder() >>> pe = PickleExplainer(sib, in_current_sage=True, default_assumptions=False, pedantic=True) >>> pe.push(sib(Integer(7))) >>> pe.stack[-Integer(1)] {atomic:7} 
 - Push a value onto the virtual machine’s stack; also mark it as shared for - sage_input()if we are in pedantic mode.- EXAMPLES: - sage: from sage.misc.explain_pickle import * sage: from sage.misc.sage_input import SageInputBuilder sage: sib = SageInputBuilder() sage: pe = PickleExplainer(sib, in_current_sage=True, default_assumptions=False, pedantic=True) sage: pe.push_and_share(sib(7)) sage: pe.stack[-1] {atomic:7} sage: pe.stack[-1]._sie_share True - >>> from sage.all import * >>> from sage.misc.explain_pickle import * >>> from sage.misc.sage_input import SageInputBuilder >>> sib = SageInputBuilder() >>> pe = PickleExplainer(sib, in_current_sage=True, default_assumptions=False, pedantic=True) >>> pe.push_and_share(sib(Integer(7))) >>> pe.stack[-Integer(1)] {atomic:7} >>> pe.stack[-Integer(1)]._sie_share True 
 - push_mark()[source]¶
- Push a ‘mark’ onto the virtual machine’s stack. - EXAMPLES: - sage: from sage.misc.explain_pickle import * sage: from sage.misc.sage_input import SageInputBuilder sage: sib = SageInputBuilder() sage: pe = PickleExplainer(sib, in_current_sage=True, default_assumptions=False, pedantic=True) sage: pe.push_mark() sage: pe.stack[-1] 'mark' sage: pe.stack[-1] is the_mark True - >>> from sage.all import * >>> from sage.misc.explain_pickle import * >>> from sage.misc.sage_input import SageInputBuilder >>> sib = SageInputBuilder() >>> pe = PickleExplainer(sib, in_current_sage=True, default_assumptions=False, pedantic=True) >>> pe.push_mark() >>> pe.stack[-Integer(1)] 'mark' >>> pe.stack[-Integer(1)] is the_mark True 
 - run_pickle(p)[source]¶
- Given an (uncompressed) pickle as a string, run the pickle in this virtual machine. Once a STOP has been executed, return the result (a - SageInputExpressionrepresenting code which, when evaluated, will give the value of the pickle).- EXAMPLES: - sage: from sage.misc.explain_pickle import * sage: from sage.misc.sage_input import SageInputBuilder sage: sib = SageInputBuilder() sage: pe = PickleExplainer(sib, in_current_sage=True, default_assumptions=False, pedantic=True) sage: sib(pe.run_pickle('T\5\0\0\0hello.')) # py2 {atomic:'hello'} - >>> from sage.all import * >>> from sage.misc.explain_pickle import * >>> from sage.misc.sage_input import SageInputBuilder >>> sib = SageInputBuilder() >>> pe = PickleExplainer(sib, in_current_sage=True, default_assumptions=False, pedantic=True) >>> sib(pe.run_pickle('T\5\0\0\0hello.')) # py2 {atomic:'hello'} 
 - Mark a - sage_input()value as shared, if we are in pedantic mode.- EXAMPLES: - sage: from sage.misc.explain_pickle import * sage: from sage.misc.sage_input import SageInputBuilder sage: sib = SageInputBuilder() sage: pe = PickleExplainer(sib, in_current_sage=True, ....: default_assumptions=False, pedantic=True) sage: v = sib(7) sage: v._sie_share False sage: pe.share(v) {atomic:7} sage: v._sie_share True - >>> from sage.all import * >>> from sage.misc.explain_pickle import * >>> from sage.misc.sage_input import SageInputBuilder >>> sib = SageInputBuilder() >>> pe = PickleExplainer(sib, in_current_sage=True, ... default_assumptions=False, pedantic=True) >>> v = sib(Integer(7)) >>> v._sie_share False >>> pe.share(v) {atomic:7} >>> v._sie_share True 
 
- class sage.misc.explain_pickle.PickleInstance(klass)[source]¶
- Bases: - object- An object which can be used as the value of a - PickleObject. Unlike other possible values of a- PickleObject, a- PickleInstancedoesn’t represent an exact value; instead, it gives the class (type) of the object.
- class sage.misc.explain_pickle.PickleObject(value, expression)[source]¶
- Bases: - object- Pickles have a stack-based virtual machine. The - explain_pickle()pickle interpreter mostly uses- sage.misc.sage_input.SageInputExpressionobjects as the stack values. However, sometimes we want some more information about the value on the stack, so that we can generate better (prettier, less confusing) code. In such cases, we push a- PickleObjectinstead of a- SageInputExpression. A- PickleObjectcontains a value (which may be a standard Python value, or a- PickleDictor- PickleInstance), an expression (a- SageInputExpression), and an “immutable” flag (which checks whether this object has been converted to a- SageInputExpression; if it has, then we must not mutate the object, since the- SageInputExpressionwould not reflect the changes).
- class sage.misc.explain_pickle.TestAppendList(iterable=(), /)[source]¶
- Bases: - list- A subclass of - list, with deliberately-broken append and extend methods. Used for testing- explain_pickle().- append()[source]¶
- A deliberately broken append method. - EXAMPLES: - sage: from sage.misc.explain_pickle import * sage: v = TestAppendList() sage: v.append(7) Traceback (most recent call last): ... TypeError: ...append() takes 1 positional argument but 2 were given - >>> from sage.all import * >>> from sage.misc.explain_pickle import * >>> v = TestAppendList() >>> v.append(Integer(7)) Traceback (most recent call last): ... TypeError: ...append() takes 1 positional argument but 2 were given - We can still append by directly using the list method: - sage: list.append(v, 7) sage: v [7] - >>> from sage.all import * >>> list.append(v, Integer(7)) >>> v [7] 
 - extend()[source]¶
- A deliberately broken extend method. - EXAMPLES: - sage: from sage.misc.explain_pickle import * sage: v = TestAppendList() sage: v.extend([3,1,4,1,5,9]) Traceback (most recent call last): ... TypeError: ...extend() takes 1 positional argument but 2 were given - >>> from sage.all import * >>> from sage.misc.explain_pickle import * >>> v = TestAppendList() >>> v.extend([Integer(3),Integer(1),Integer(4),Integer(1),Integer(5),Integer(9)]) Traceback (most recent call last): ... TypeError: ...extend() takes 1 positional argument but 2 were given - We can still extend by directly using the list method: - sage: list.extend(v, (3,1,4,1,5,9)) sage: v [3, 1, 4, 1, 5, 9] - >>> from sage.all import * >>> list.extend(v, (Integer(3),Integer(1),Integer(4),Integer(1),Integer(5),Integer(9))) >>> v [3, 1, 4, 1, 5, 9] 
 
- class sage.misc.explain_pickle.TestAppendNonlist[source]¶
- Bases: - object- A list-like class, carefully designed to test exact unpickling behavior. Used for testing - explain_pickle().
- class sage.misc.explain_pickle.TestBuild[source]¶
- Bases: - object- A simple class with a - __getstate__()but no- __setstate__(). Used for testing- explain_pickle().
- class sage.misc.explain_pickle.TestBuildSetstate[source]¶
- Bases: - TestBuild- A simple class with a - __getstate__()and a- __setstate__(). Used for testing- explain_pickle().
- class sage.misc.explain_pickle.TestGlobalFunnyName[source]¶
- Bases: - object- A featureless new-style class which has a name that’s not a legal Python identifier. - EXAMPLES: - sage: from sage.misc.explain_pickle import * sage: globals()['funny$name'] = TestGlobalFunnyName # see comment at end of file sage: TestGlobalFunnyName.__name__ 'funny$name' sage: globals()['funny$name'] is TestGlobalFunnyName True - >>> from sage.all import * >>> from sage.misc.explain_pickle import * >>> globals()['funny$name'] = TestGlobalFunnyName # see comment at end of file >>> TestGlobalFunnyName.__name__ 'funny$name' >>> globals()['funny$name'] is TestGlobalFunnyName True 
- class sage.misc.explain_pickle.TestGlobalNewName[source]¶
- Bases: - object- A featureless new-style class. When you try to unpickle an instance of - TestGlobalOldName, it is redirected to create an instance of this class instead. Used for testing- explain_pickle().- EXAMPLES: - sage: from sage.misc.explain_pickle import * sage: loads(dumps(TestGlobalOldName())) TestGlobalNewName - >>> from sage.all import * >>> from sage.misc.explain_pickle import * >>> loads(dumps(TestGlobalOldName())) TestGlobalNewName 
- class sage.misc.explain_pickle.TestGlobalOldName[source]¶
- Bases: - object- A featureless new-style class. When you try to unpickle an instance of this class, it is redirected to create a - TestGlobalNewNameinstead. Used for testing- explain_pickle().- EXAMPLES: - sage: from sage.misc.explain_pickle import * sage: loads(dumps(TestGlobalOldName())) TestGlobalNewName - >>> from sage.all import * >>> from sage.misc.explain_pickle import * >>> loads(dumps(TestGlobalOldName())) TestGlobalNewName 
- class sage.misc.explain_pickle.TestReduceGetinitargs[source]¶
- Bases: - object- An old-style class with a - __getinitargs__()method. Used for testing- explain_pickle().
- class sage.misc.explain_pickle.TestReduceNoGetinitargs[source]¶
- Bases: - object- An old-style class with no - __getinitargs__()method. Used for testing- explain_pickle().
- sage.misc.explain_pickle.explain_pickle(pickle=None, file=None, compress=True, **kwargs)[source]¶
- Explain a pickle. That is, produce source code such that evaluating the code is equivalent to loading the pickle. Feeding the result of - explain_pickle()to- sage_eval()should be totally equivalent to loading the- picklewith- cPickle.- INPUT: - pickle– string (default:- None); the pickle to explain
- file– a filename of a pickle (default:- None)
- compress– boolean (default:- True); if- False, don’t attempt to decompress the pickle
- in_current_sage– boolean (default:- False); if- True, produce potentially simpler code that is tied to the current version of Sage
- default_assumptions– boolean (default:- False); if- True, produce potentially simpler code that assumes that generic unpickling code will be used. This code may not actually work.
- eval– boolean (default:- False); if- True, then evaluate the resulting code and return the evaluated result
- preparse– if- True, then produce code to be evaluated with Sage’s preparser; if- False, then produce standard Python code; if- None, then produce code that will work either with or without the preparser. (default:- True)
- pedantic– boolean (default:- False); if- True, then carefully ensures that the result has at least as much sharing as the result of cPickle (it may have more, for immutable objects)
 - Exactly one of - pickle(a string containing a pickle) or- file(the filename of a pickle) must be provided.- EXAMPLES: - sage: explain_pickle(dumps({('a', 'b'): [1r, 2r]})) {('a', 'b'):[1r, 2r]} sage: explain_pickle(dumps(RR(pi)), in_current_sage=True) # needs sage.symbolic from sage.rings.real_mpfr import __create__RealNumber_version0 from sage.rings.real_mpfr import __create__RealField_version0 __create__RealNumber_version0(__create__RealField_version0(53r, False, 'RNDN'), '3.4gvml245kc0@0', 32r) sage: s = 'hi' sage: explain_pickle(dumps((s, s))) ('hi', 'hi') sage: explain_pickle(dumps((s, s)), pedantic=True) si = 'hi' (si, si) sage: explain_pickle(dumps(5r)) 5r sage: explain_pickle(dumps(5r), preparse=False) 5 sage: explain_pickle(dumps(5r), preparse=None) int(5) sage: explain_pickle(dumps(22/7)) pg_make_rational = unpickle_global('sage.rings.rational', 'make_rational') pg_make_rational('m/7') sage: explain_pickle(dumps(22/7), in_current_sage=True) from sage.rings.rational import make_rational make_rational('m/7') sage: explain_pickle(dumps(22/7), default_assumptions=True) from sage.rings.rational import make_rational make_rational('m/7') - >>> from sage.all import * >>> explain_pickle(dumps({('a', 'b'): [1, 2]})) {('a', 'b'):[1r, 2r]} >>> explain_pickle(dumps(RR(pi)), in_current_sage=True) # needs sage.symbolic from sage.rings.real_mpfr import __create__RealNumber_version0 from sage.rings.real_mpfr import __create__RealField_version0 __create__RealNumber_version0(__create__RealField_version0(53r, False, 'RNDN'), '3.4gvml245kc0@0', 32r) >>> s = 'hi' >>> explain_pickle(dumps((s, s))) ('hi', 'hi') >>> explain_pickle(dumps((s, s)), pedantic=True) si = 'hi' (si, si) >>> explain_pickle(dumps(5)) 5r >>> explain_pickle(dumps(5), preparse=False) 5 >>> explain_pickle(dumps(5), preparse=None) int(5) >>> explain_pickle(dumps(Integer(22)/Integer(7))) pg_make_rational = unpickle_global('sage.rings.rational', 'make_rational') pg_make_rational('m/7') >>> explain_pickle(dumps(Integer(22)/Integer(7)), in_current_sage=True) from sage.rings.rational import make_rational make_rational('m/7') >>> explain_pickle(dumps(Integer(22)/Integer(7)), default_assumptions=True) from sage.rings.rational import make_rational make_rational('m/7') 
- sage.misc.explain_pickle.explain_pickle_string(pickle, in_current_sage=False, default_assumptions=False, eval=False, preparse=True, pedantic=False)[source]¶
- This is a helper function for - explain_pickle(). It takes a decompressed pickle string as input; other than that, its options are all the same as- explain_pickle().- EXAMPLES: - sage: sage.misc.explain_pickle.explain_pickle_string(dumps("Hello, world", compress=False)) 'Hello, world' - >>> from sage.all import * >>> sage.misc.explain_pickle.explain_pickle_string(dumps("Hello, world", compress=False)) 'Hello, world' - (See the documentation for - explain_pickle()for many more examples.)
- sage.misc.explain_pickle.name_is_valid(name)[source]¶
- Test whether a string is a valid Python identifier. (We use a conservative test, that only allows ASCII identifiers.) - EXAMPLES: - sage: from sage.misc.explain_pickle import name_is_valid sage: name_is_valid('fred') True sage: name_is_valid('Yes!ValidName') False sage: name_is_valid('_happy_1234') True - >>> from sage.all import * >>> from sage.misc.explain_pickle import name_is_valid >>> name_is_valid('fred') True >>> name_is_valid('Yes!ValidName') False >>> name_is_valid('_happy_1234') True 
- sage.misc.explain_pickle.test_pickle(p, verbose_eval=False, pedantic=False, args=())[source]¶
- Test - explain_pickle()on a given pickle- p.- pcan be:- a string containing an uncompressed pickle (which will always end with a ‘.’) 
- a string containing a pickle fragment (not ending with ‘.’) test_pickle will synthesize a pickle that will push args onto the stack (using persistent IDs), run the pickle fragment, and then STOP (if the string ‘mark’ occurs in args, then a mark will be pushed) 
- an arbitrary object; - test_pickle()will pickle the object
 - Once it has a pickle, - test_pickle()will print the pickle’s disassembly, run- explain_pickle()with- in_current_sage=Trueand- False, print the results, evaluate the results, unpickle the object with cPickle, and compare all three results.- If - verbose_evalis- True, then- test_pickle()will print messages before evaluating the pickles; this is to allow for tests where the unpickling prints messages (to verify that the same operations occur in all cases).- EXAMPLES: - sage: from sage.misc.explain_pickle import * sage: test_pickle(['a']) 0: \x80 PROTO 2 2: ] EMPTY_LIST 3: q BINPUT 0 5: X BINUNICODE 'a' 11: q BINPUT 1 13: a APPEND 14: . STOP highest protocol among opcodes = 2 explain_pickle in_current_sage=True/False: ['a'] result: ['a'] - >>> from sage.all import * >>> from sage.misc.explain_pickle import * >>> test_pickle(['a']) 0: \x80 PROTO 2 2: ] EMPTY_LIST 3: q BINPUT 0 5: X BINUNICODE 'a' 11: q BINPUT 1 13: a APPEND 14: . STOP highest protocol among opcodes = 2 explain_pickle in_current_sage=True/False: ['a'] result: ['a'] 
- sage.misc.explain_pickle.unpickle_appends(lst, vals)[source]¶
- Given a list (or list-like object) and a sequence of values, appends the values to the end of the list. This is careful to do so using the exact same technique that cPickle would use. Used by - explain_pickle().- EXAMPLES: - sage: v = [] sage: unpickle_appends(v, (1, 2, 3)) sage: v [1, 2, 3] - >>> from sage.all import * >>> v = [] >>> unpickle_appends(v, (Integer(1), Integer(2), Integer(3))) >>> v [1, 2, 3] 
- sage.misc.explain_pickle.unpickle_build(obj, state)[source]¶
- Set the state of an object. Used by - explain_pickle().- EXAMPLES: - sage: from sage.misc.explain_pickle import * sage: v = EmptyNewstyleClass() sage: unpickle_build(v, {'hello': 42}) sage: v.hello 42 - >>> from sage.all import * >>> from sage.misc.explain_pickle import * >>> v = EmptyNewstyleClass() >>> unpickle_build(v, {'hello': Integer(42)}) >>> v.hello 42 
- sage.misc.explain_pickle.unpickle_extension(code)[source]¶
- Take an integer index and return the extension object with that index. Used by - explain_pickle().- EXAMPLES: - sage: from copyreg import * sage: add_extension('sage.misc.explain_pickle', 'EmptyNewstyleClass', 42) sage: unpickle_extension(42) <class 'sage.misc.explain_pickle.EmptyNewstyleClass'> sage: remove_extension('sage.misc.explain_pickle', 'EmptyNewstyleClass', 42) - >>> from sage.all import * >>> from copyreg import * >>> add_extension('sage.misc.explain_pickle', 'EmptyNewstyleClass', Integer(42)) >>> unpickle_extension(Integer(42)) <class 'sage.misc.explain_pickle.EmptyNewstyleClass'> >>> remove_extension('sage.misc.explain_pickle', 'EmptyNewstyleClass', Integer(42)) 
- sage.misc.explain_pickle.unpickle_instantiate(fn, args)[source]¶
- Instantiate a new object of class - fnwith arguments- args. Almost always equivalent to- fn(*args). Used by- explain_pickle().- EXAMPLES: - sage: unpickle_instantiate(Integer, ('42',)) 42 - >>> from sage.all import * >>> unpickle_instantiate(Integer, ('42',)) 42 
- sage.misc.explain_pickle.unpickle_newobj(klass, args)[source]¶
- Create a new object; this corresponds to the C code - klass->tp_new(klass, args, NULL). Used by- explain_pickle().- EXAMPLES: - sage: unpickle_newobj(tuple, ([1, 2, 3],)) (1, 2, 3) - >>> from sage.all import * >>> unpickle_newobj(tuple, ([Integer(1), Integer(2), Integer(3)],)) (1, 2, 3) 
- sage.misc.explain_pickle.unpickle_persistent(s)[source]¶
- Take an integer index and return the persistent object with that index; works by calling whatever callable is stored in - unpickle_persistent_loader. Used by- explain_pickle().- EXAMPLES: - sage: import sage.misc.explain_pickle sage: sage.misc.explain_pickle.unpickle_persistent_loader = lambda n: n+7 sage: unpickle_persistent(35) 42 - >>> from sage.all import * >>> import sage.misc.explain_pickle >>> sage.misc.explain_pickle.unpickle_persistent_loader = lambda n: n+Integer(7) >>> unpickle_persistent(Integer(35)) 42