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...reverse of the path to be taken. Below is an example of Dijkstra's shortest path algorithm on a graph with weighted edges using a table (a faster version that uses a heap is available, but this version is offered due to its similarity to the description above, the heap version is available via older versions of this document). def DijkstraSP_table(graph, S, T): table = {} #3 for node in graph.iterkeys(): #(visited, distance, node,...
...reverse operation, except when the current frame is the entry frame of the interpreter when it will return as normal. Rejected Ideas None, as yet. Open Issues None, as yet. Copyright This document is placed in the public domain or under the CC0-1.0-Universal license, whichever is more permissive. Source: https://github.com/python/peps/blob/master/pep-0651.rst
...reversed, it should be possible to yield without passing an explicit value (yield is of course equivalent to yield None). When send(value) is called, the yield-expression that it resumes will return the passed-in value. When next() is called, the resumed yield-expression will return None. If the yield-expression is a yield-statement, this returned value is ignored, similar to ignoring the value returned by a function call used as a statement. In effect, a yield-expression is like an inverted f...
...reverses any locale-dependent changes made to floating-point numbers. Martin and Guido pointed out potential copyright issues with the contributed code. I believe we will have no problems in this area as members of the GTK+ and glib teams have said they are fine with relicensing the code, and a PSF contributor agreement has been mailed in to ensure this safety. Tim Peters has pointed out [9] that there are situations involving threading in which the proposed change is insufficient to solve the ...
...reverses a string. None - assignment to variables or attributes named None will now trigger a warning. In the future, None may become a keyword. New-style classes now allow assignment to __name__ and __bases__. Interned strings are no longer immortal. sys.setcheckinterval() - the default value for this feature has changed from 10 to 100, for faster execution of interleaving multiple threads (by switching threads less frequently). Universal newlines - files opened for reading with the special mo...
...reverse of arrangement in the io module), so the original PEP 100 design required that codec writers provide appropriate StreamReader and StreamWriter implementations in addition to the core codec encode() and decode() methods. This places a heavy burden on codec authors providing these specialised implementations to correctly handle many of the corner cases (see Appendix A) that have now been dealt with by io.TextIOWrapper. While deeper integration between the codec and the stream allows for ad...
...Reverse Iteration. PEP 327: A Decimal package for fixed precision arithmetic. PEP 328: Multi-line Imports Encapsulate the decorate-sort-undecorate pattern in a keyword for list.sort(). Added a builtin called sorted() which may be used in expressions. The itertools module has two new functions, tee() and groupby(). Add a collections module with a deque() object. Add two statistical/reduction functions, nlargest() and nsmallest() to the heapq module. Python's windows installer now uses MSI Defe...
...reverse', 'sort'] >>> Under the new proposal, the __methods__ attribute no longer exists: >>> [].__methods__ Traceback (most recent call last): File "<stdin>", line 1, in ? AttributeError: 'list' object has no attribute '__methods__' >>> Instead, you can get the same information from the list type: >>> T = [].__class__ >>> T <type 'list'> >>> dir(T) # like T.__dict__.keys(), but sorted ['__add__', '__class__',...
...reverse dependencies on PyPI (for comparison, requests has about 28000 reverse dependencies). Hence, this is likely to be a generally useful addition, even looking beyond the needs of Python packaging and related tools. Rationale This PEP proposes basing the standard library support for reading TOML on the third-party library tomli (github.com/hukkin/tomli). Many projects have recently switched to using tomli, such as pip, build, pytest, mypy, black, flit, coverage, setuptools-scm and cibuildw...
PEP 335 -- Overloadable Boolean Operators PEP:335 Title:Overloadable Boolean Operators Author:Gregory Ewing <greg.ewing at canterbury.ac.nz> Status:Rejected Type:Standards Track Created:29-Aug-2004 Python-Version:3.3 Post-History:05-Sep-2004, 30-Sep-2011, 25-Oct-2011 Contents Rejection Notice Abstract Background Motivation Rationale Specification Special Methods Bytecodes Type Slots Python/C API Functions Alternatives and Optimisations Reduced special method set Additi...
...reverse(), .pop(), .remove(). Bytes and the Str Type Like the bytes type in Python 3.0a1, and unlike the relationship between str and unicode in Python 2.x, attempts to mix bytes (or bytearray) objects and str objects without specifying an encoding will raise a TypeError exception. (However, comparing bytes/bytearray and str objects for equality will simply return False; see the section on Comparisons above.) Conversions between bytes or bytearray objects and str objects must always be explic...
...reverse', 'sort'] >>> >>> dir([]) ['append', 'count', 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort'] Under the new proposal, the __methods__ attribute no longer exists: Python 2.2c1 (#803, Dec 13 2001, 23:06:05) [GCC egcs-2.91.66 19990314/Linux (egcs-1.1.2 release)] on linux2 Type "copyright", "credits" or "license" for more information. >>> [].__methods__ Traceback (most recent call last): File "<stdin>", line 1...
...reverse', 'sort'] >>> >>> dir([]) ['append', 'count', 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort'] Under the new proposal, the __methods__ attribute no longer exists: Python 2.2c1 (#803, Dec 13 2001, 23:06:05) [GCC egcs-2.91.66 19990314/Linux (egcs-1.1.2 release)] on linux2 Type "copyright", "credits" or "license" for more information. >>> [].__methods__ Traceback (most recent call last): File "<stdin>", line 1, in ? AttributeError: 'list' object ha...
PEP 3141 -- A Type Hierarchy for Numbers PEP:3141 Title:A Type Hierarchy for Numbers Author:Jeffrey Yasskin <jyasskin at google.com> Status:Final Type:Standards Track Created:23-Apr-2007 Post-History:25-Apr-2007, 16-May-2007, 02-Aug-2007 Contents Abstract Rationale Specification Numeric Classes Changes to operations and __magic__ methods Notes for type implementors Adding More Numeric ABCs Implementing the arithmetic operations Rejected Alternatives The Decimal Type R...
...reverse order, after all of the function's "primary" methods are executed. That is, they are executed least-specific methods first, with ambiguous methods being executed in the reverse of the order in which they were added. The return values of both "before" and "after" methods are ignored, and any uncaught exceptions raised by any methods (primary or other) immediately end the dispatching process. "Before" and "after" methods cannot have __proceed__ arguments, as they are not responsible for ...
...reversed__, index, and count for free. Explicit subclassing makes it explicit that a class implements a particular protocol, making subtyping relationships easier to see. Type checkers can warn about missing protocol members or members with incompatible types more easily, without having to use hacks like dummy assignments discussed above in this section. Explicit subclassing makes it possible to force a class to be considered a subtype of a protocol (by using # type: ignore together with an expl...
...reversed this process. Not that it took me very long to learn the feature set. I wrote a working, usable fetchmailconf, with GUI, in six working days, of which perhaps the equivalent of two days were spent learning Python itself. This reflects another useful property of the language: it is compact -- you can hold its entire feature set (and at least a concept index of its libraries) in your head. C is a famously compact language. Perl is notoriously not; one of the things the notion "There'...
...reverse. A further proof of the ambiguity of this segmentation is that the standard library itself sometimes has problems deciding. For example, in the select module, similar failures will raise select.error, OSError or IOError depending on whether you are using select(), a poll object, a kqueue object, or an epoll object. This makes user code uselessly complicated since it has to be prepared to catch various exception types, depending on which exact implementation of a single primitive it cho...