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...algorithms in Python. Currently, if a program needs to deeply recurse it must manage the maximum recursion depth allowed, hopefully managing to set it in the region between the minimum needed to run correctly and the maximum that is safe to avoid a memory protection error. By separating the checks for C stack overflow from checks for recursion depth, pure Python programs can run safely, using whatever level of recursion they require. Rationale CPython currently relies on a single limit to guar...
...Algorithm Transition Plan If the algorithm used to hash target and metadata files becomes vulnerable, it SHOULD be replaced by a stronger hash algorithm. The TUF metadata format allows to list digests from different hash algorithms alongside each other, together with an algorithm identifier, so that clients can seamlessly switch between algorithms. However, once support for an old algorithm is turned off, clients that don't support the new algorithm will only be able to install or update ...
...Sort for BLists, so that best-case sorting is O(n) instead of O(log n). Implement __reversed__ Cache a pointer in the root to the rightmost leaf, to make LIFO operation O(n) time. References [1](1, 2) Reference Implementations for C and Python: http://www.python.org/pypi/blist/ [2]Empirical performance comparison between Python's array-based list and the blist: http://stutzbachenterprises.com/blist/ [3]Discussion on python-3000 starting at post: https://mail.python.org/pipermail/...
...sorted in lexicographic order. Within the file, the tables for the projects SHOULD be sorted by: Project/key name in lexicographic order Package version, newest/highest to older/lowest according to the version specifiers spec Optional dependencies (extras) via lexicographic order File name based on the filename field (discussed below) These recommendations are to help minimize diff changes between tool executions. package._name_._version_.filename This field is required. A string representing...
...sorted() builtin function that returns a new sorted list from any iterable. CObjects are now mutable (on the C level) through PyCObject_SetVoidPtr. list.sort() now supports three keyword arguments: cmp, key, and reverse. The key argument can be a function of one argument that extracts a comparison key from the original record: mylist.sort(key=str.lower). The reverse argument is a boolean value and if True will change the sort order as if the comparison arguments were reversed. In addition, th...
...Sort as an empty tuple if unspecified, else sort as a two-item tuple with the first item being the initial digits as an int, and the second item being the remainder of the tag as a str. language implementation and version tag E.g. 'py27', 'py2', 'py3'. abi tag E.g. 'cp33m', 'abi3', 'none'. platform tag E.g. 'linux_x86_64', 'any'. For example, distribution-1.0-1-py27-none-any.whl is the first build of a package called 'distribution', and is compatible with Python 2.7 (any Python 2.7 implementati...
...Sort as the empty string if unspecified, else sort the initial digits as a number, and the remainder lexicographically. language implementation and version tag E.g. 'py27', 'py2', 'py3'. abi tag E.g. 'cp33m', 'abi3', 'none'. platform tag E.g. 'linux_x86_64', 'any'. For example, distribution-1.0-1-py27-none-any.whl is the first build of a package called 'distribution', and is compatible with Python 2.7 (any Python 2.7 implementation), with no ABI (pure Python), on any CPU architecture. The last ...
...sort() has a new implementation. While cross-platform results may vary, and in data-dependent ways, this is much faster on many kinds of partially ordered lists than the previous implementation, and reported to be just as fast on randomly ordered lists on several major platforms. This sort is also stable (if A==B and A precedes B in the list at the start, A precedes B after the sort too), although the language definition does not guarantee stability. A potential drawback is that list.sort() m...
...algorithms Fields redeclared in subclasses Django primary and foreign keys Open Issues converter field descriptor parameter References Copyright Abstract PEP 557 introduced the dataclass to the Python stdlib. Several popular libraries have behaviors that are similar to dataclasses, but these behaviors cannot be described using standard type annotations. Such projects include attrs, pydantic, and object relational mapper (ORM) packages such as Django and EdgeDB. Most type checkers, linters...
...algorithm # uses a precision 2 greater than normal return +s # Convert result to normal precision def sin(x): with localcontext(ExtendedContext): # Rest of sin calculation algorithm # uses the Extended Context from the # General Decimal Arithmetic Specification return +s # Convert result to normal context A generic "object-closing" context manager: class closing(object): def __init__(self, obj): self.obj = obj def __enter__(self): ...
...sorts of grief. In the past, this couldn't be fixed due to backwards compatibility concerns. However, scripts potentially affected by this problem will already require fixes when porting to the Python 3.x (due to the elimination of implicit relative imports when importing modules normally). This provides a convenient opportunity to implement a corresponding change in the initialisation semantics for sys.path[0]. Importing the main module twice Another venerable trap is the issue of importing _...
...algorithm more efficiently; but the algorithm implemented should be the same. Currently the algorithm is fully specified only by the source code [15]. Note: the issubset and issuperset methods found on the set type in Python 2 are not supported, as these are mostly just aliases for __le__ and __ge__. MutableSet This is a subclass of Set implementing additional operations to add and remove elements. The supported methods have the semantics known from the set type in Python 2 (except for discar...
...algorithms. We all live in our own little sub-communities, so some Python users may be surprised to realize the sheer extent to which Python is used for number crunching -- especially since much of this particular sub-community's activity occurs outside of traditional Python/FOSS channels. So, to give some rough idea of just how many numerical Python programmers are actually out there, here are two numbers: In 2013, there were 7 international conferences organized specifically on numerical Pyth...
...algorithms, etc., and those extensions will be treated as first-class citizens by the proposed API. The API will be implemented in pure Python with no C, but may have some dependency on CPython-specific features such as sys._getframe and the func_code attribute of functions. It is expected that e.g. Jython and IronPython will have other ways of implementing similar functionality (perhaps using Java or C#). Rationale and Goals Python has always provided a variety of built-in and standard-libra...
...sort(seq): match seq: case [] | [_]: return seq case [x, y] if x <= y: return seq case [x, y]: return [y, x] case [x, y, z] if x <= y <= z: return seq case [x, y, z] if x >= y >= z: return [z, y, x] case [p, *rest]: a = sort([x for x in rest if x <= p]) b = sort([x for x in rest if p < x]) return a + [p] + b Patterns Patterns...
...algorithm - the hash algorithms must be consistent for the lifetime of the process, and so they must be in place before the core interpreter is created. The essential settings needed are a flag indicating whether or not to use a specific seed value for the randomised hashes, and if so, the specific value for the seed (a seed value of zero disables randomised hashing). In addition, due to the possible use of PYTHONHASHSEED in configuring the hash randomisation, the question of whether or not to c...
...algorithm, where the name of the class is mangled into the attribute name. This helps avoid attribute name collisions should subclasses inadvertently contain attributes with the same name. Note 1: Note that only the simple class name is used in the mangled name, so if a subclass chooses both the same class name and attribute name, you can still get name collisions. Note 2: Name mangling can make certain uses, such as debugging and __getattr__(), less convenient. However the name mangling algor...
...algorithm that the tool considers too weak to trust, automated tools SHOULD at least emit a warning and MAY refuse to rely on the URL. If such a source URL also uses an insecure transport, automated tools SHOULD NOT rely on the URL. For source archive references, an expected hash value may be specified by including a <hash-algorithm>=<expected-hash> entry as part of the URL fragment. As of 2017, it is RECOMMENDED that 'sha256' hashes be used for source URLs, as this hash is not yet k...
...sort. The server's documentation should include an explanation of how to configure this or where to find the recorded output. A server or gateway may supply different error streams to different applications, if this is desired. web3.multithread This value should evaluate true if the application object may be simultaneously invoked by another thread in the same process, and should evaluate false otherwise. web3.multiprocess This value should evaluate true if an equivalent application object ...
...sort. The server's documentation should include an explanation of how to configure this or where to find the recorded output. A server or gateway may supply different error streams to different applications, if this is desired. wsgi.multithread This value should evaluate true if the application object may be simultaneously invoked by another thread in the same process, and should evaluate false otherwise. wsgi.multiprocess This value should evaluate true if an equivalent application object ...