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...length of its data with a Python LONG_LONG type. Even though the current definition for PyBufferProcs restricts the length to be the size of an int, this PEP does not propose to make any changes there. Instead, extensions can work around this limit by making an explicit PyBytes_Check(...) call, and if that succeeds they can make a PyBytes_GetReadBuffer(...) or PyBytes_GetWriteBuffer call to get the pointer and full length of the object as a LONG_LONG. The bytes object will raise an exception i...
...len(co_code) > 0). The bytecode string cannot exceed a maximum size (len(co_code) < sizeof(unsigned char) - 1). The first instruction in the bytecode string begins at index 0. Only valid byte-codes with the correct number of operands can be in the bytecode string. Static Constraints on Bytecode Instruction Operands The target of a jump instruction must be within the code boundaries and must fall on an instruction, never between an instruction and its operands. The operand of a LOAD_* i...
...len(line) - len(stripped)) # Remove indentation (first line is special): trimmed = [lines[0].strip()] if indent < sys.maxint: for line in lines[1:]: trimmed.append(line[indent:].rstrip()) # Strip off trailing and leading blank lines: while trimmed and not trimmed[-1]: trimmed.pop() while trimmed and not trimmed[0]: trimmed.pop(0) # Return a single string: return '\n'.join(trimmed) The docstring in this example contains two n...
...len(x) is represented as the bytecode CALL_FUNCTION 1. In this case we would always expect the object len to be the function. We probably don't want to specialize for len (although we might for type and isinstance), but it would be beneficial to specialize for builtin functions taking a single argument. A fast check that the underlying function is a builtin function taking a single argument (METHOD_O) would allow us to avoid a sequence of checks for number of parameters and keyword arguments. CA...
...len(l)): ... print l[i] a b c d Or, to start at the second element of l and processing only every second element from then on: >>> for i in range(1, len(l), 2): ... print l[i] b d There are several disadvantages with this approach: Clarity of purpose: Adding another function call, possibly with extra arithmetic to determine the desired length and step of the list, does not improve readability of the code. Also, it is possible to "shadow" the builtin range function by supply...
...len(x), and repr(x). In particular, these behaviors will be dropped: x[i:j] (slicing) x*n, n*x (sequence-repeat) cmp(x1, x2) (comparisons) i in x (containment test) x.tolist() method x.start, x.stop, x.step attributes I also propose to change the signature of the PyRange_New() C API to remove the 4th argument (the repetition count). By implementing a custom iterator type, we could speed up the common use, but this is optional (the default sequence iterator does just fine). Scope This PEP aff...
...lenty of implementations in pure Python available (including Demo/classes/Rat.py). PEP 240 - Adding a Rational Literal to Python - Zadka Given my comments on 239, I propose to reject this. PEP 242 - Numeric Kinds - Dubois Nobody except the author seems to be interested in pursueing this. Personally, I think the idea is not particularly Pythonic -- the trend is towards fewer numeric types, nor more (see PEP 237). I believe the author has said that it would be better to retrac...
...len(val) == 2 def func(names: Tuple[str, ...]): if is_two_element_tuple(names): reveal_type(names) # Tuple[str, str] else: reveal_type(names) # Tuple[str, ...] Type checkers should assume that type narrowing should be applied to the expression that is passed as the first positional argument to a user-defined type guard. If the type guard function accepts more than one argument, no type narrowing is applied to those additional argument expressions. If a type guard func...
...len=len, KeyError=KeyError): ... # 60 line function return decorating_function # Becomes: return ?.decorating_function given: # Cell variables rather than locals, but should give similar speedup tuple, sorted, len, KeyError = tuple, sorted, len, KeyError def decorating_function(user_function): ... # 60 line function # This example also nicely makes it clear that there is nothing in the # function after the nested function definition. Due to additional # nested functions, that isn't...
...lent to: >>> 'result=' + str(foo()) 'result=20' Expressions are parsed with the equivalent of ast.parse('(' + expression + ')', '<fstring>', 'eval') [7]. Note that since the expression is enclosed by implicit parentheses before evaluation, expressions can contain newlines. For example: >>> x = 0 >>> f'''{x ... +1}''' '1' >>> d = {0: 'zero'} >>> f'''{d[0 ... ]}''' 'zero' Format specifiers Format specifiers may also contain evaluated expres...
...len__. The __len__ method should return an Integer (see "Numbers" below) >= 0. The abstract __len__ method returns 0. Invariant: If a class C derives from Sized as well as from Iterable, the invariant sum(1 for x in c) == len(c) should hold for any instance c of C. Container The base class for classes defining __contains__. The __contains__ method should return a bool. The abstract __contains__ method returns False. Invariant: If a class C derives from Container as well as from Iterable,...
...len("abc") with 3, guards on builtins.__dict__['len'] and globals()['len'] are required Loop unrolling: to unroll the loop for i in range(...): ..., guards on builtins.__dict__['range'] and globals()['range'] are required etc. Pyjion According of Brett Cannon, one of the two main developers of Pyjion, Pyjion can benefit from dictionary version to implement optimizations. Pyjion is a JIT compiler for Python based upon CoreCLR (Microsoft .NET Core runtime). Cython Cython can benefit from dict...
...length sequence pattern fails if the length of the subject sequence is not equal to the number of subpatterns. A variable-length sequence pattern fails if the length of the subject sequence is less than the number of non-star subpatterns. The length of the subject sequence is obtained using the builtin len() function (i.e., via the __len__ protocol). However, the interpreter may cache this value in a similar manner as described for value patterns. A fixed-length sequence pattern matches the sub...
...len(sequence)) On the assumption that adding functionality to an existing built-in function may be less intrusive than adding a new built-in function, this PEP proposes adding this functionality to the existing functions range() and xrange(). Specification It is proposed that all three arguments to the built-in functions range() and xrange() are allowed to be objects with a length (i.e. objects implementing the __len__ method). If an argument cannot be interpreted as an integer (i.e. it has ...
...lename): self = sys.get_generator() myfile = open(filename) for line in myfile: if len(line) < 10: continue self.pos = myfile.tell() yield line.upper() g = mygen('sample.txt') line1 = g.next() print 'Position', g.pos Uses for generator attributes include: Providing generator clients with extra information (as shown above). Externally setting control flags governing generator operation (possibly telling a generator when to step in or step over...
...len(expensive() -> res) == 4: dosomething(res) Keep the iterator object from the for loop: for ch in expensive() -> res: sell_on_internet(res) Corner case: for ch -> please_dont in expensive(): pass # who would want to do this? Not I. References [1]Issue1714448 "if something as x:", k0wax http://bugs.python.org/issue1714448 Copyright This document has been placed in the public domain. Source: https://github.com/python/peps/blob/master/pep-0379.txt
...len(), then F is a function that contains a nested function (G) with a free variable (len). The label "free-in-nested" will be used to describe these functions. import * used in function scope The language reference specifies that import * may only occur in a module scope. (Sec. 6.11) The implementation of C Python has supported import * at the function scope. If import * is used in the body of a free-in-nested function, the compiler will issue a warning. Under future semantics, the compile...
...len(x) == n or "key" in x as guards to select an applicable block. The block can then assume x supports the interface checked by the guard. For example: if isinstance(x, tuple) and len(x) == 2: host, port = x mode = "http" elif isinstance(x, tuple) and len(x) == 3: host, port, mode = x # Etc. Code like this is more elegantly rendered using match: match x: case host, port: mode = "http" case host, port, mode: pass # Etc. AST traversal code often look...
...len(b) < 15: ... b += raw_stdin.read(15) abcedfghijklm b'abcdefghijklm\r\n' Using the raw object with small buffers Code that uses the raw IO object and attempts to read less than four characters will now receive an error. Because it's possible that any single character may require up to four bytes when represented in utf-8, requests must fail: >>> raw_stdin = sys.stdin.buffer.raw >>> data = raw_stdin.read(3) Traceback (most recent call last): File "<stdin>",...
...length of strings passed to the encrypt() and decrypt() must be a multiple of the block size. key_size An integer value; the size of the keys required by this module, measured in bytes. If key_size is None, then the algorithm accepts variable-length keys. This may mean the module accepts keys of any random length, or that there are a few different possible lengths, e.g. 16, 24, or 32 bytes. You cannot pass a key of length 0 (that is, the null string '') as a variable-length key. Cipher obj...