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...data = raw_stdin.read(15) abcdefghijklm b'abc' # data contains at most 3 characters, and never more than 12 bytes # error, as "defghijklm\r\n" is passed to the interactive prompt To correct this code, the buffered reader/writer should be used, or the caller should continue reading until its buffer is full: >>> # Fix 1: Use the buffered reader/writer >>> stdin = sys.stdin.buffer >>> data = stdin.read(15) abcedfghijklm b'abcdefghijklm\r\n' >>> # Fix 2: Loop u...
...data, 0) reduce(lambda s, a: s + a[3], data, 0) These simplify to: sum(a.myattr for a in data) sum(a[3] for a in data) List comprehensions greatly reduced the need for filter() and map(). Likewise, generator expressions are expected to minimize the need for itertools.ifilter() and itertools.imap(). In contrast, the utility of other itertools will be enhanced by generator expressions: dotproduct = sum(x*y for x,y in itertools.izip(x_vector, y_vector)) Having a syntax similar to list compreh...
...data structures describing biomolecules. Choice of languages The choice of Python plus C was made after an evaluation of various languages. I was rapidly convinced that only a mixture of a high-level interpreted language and a CPU-efficient compiled language could meet my seemingly conflicting requirements of rapid development and efficient execution. For the high-level part, Tcl was ruled out because it could not handle the complex data structures required by the project. Perl was ruled out b...
...data type is needed and why other numeric data types are not enough. I wanted a Money data type, and after proposing a pre-PEP in comp.lang.python, the community agreed to have a numeric data type with the needed arithmetic behaviour, and then build Money over it: all the considerations about quantity of digits after the decimal point, rounding, etc., will be handled through Money. It is not the purpose of this PEP to have a data type that can be used as Money without further effort. One of the...
...data": data where the structure of the data is known in advance, but pieces of it may be missing at runtime, and the software manipulating that data is expected to degrade gracefully (e.g. by omitting results that depend on the missing data) rather than failing outright. Some particularly common cases where this issue arises are: handling optional application configuration settings and function parameters handling external service failures in distributed systems handling data sets that include ...
...data) if m: ... else: m = other_pattern.match(data) if m: ... else: m = yet_another_pattern.match(data) if m: ... else: ... As with PEP 572, this PEP allows the else/if portions of that chain to be condensed, making their consistent and mutually exclusive structure more readily apparent: m = pattern.match(data) if m: ... elif m := other_pattern.match(data): ... elif m := yet_another_pattern.match(data): ... els...
...data typing and very late binding Tight integration with C, C++, and Java modules May be compiled to Java byte code for use in any JVM String and regular expression processing Extensive XML and web services support HTTP, FTP, SMTP, POP, IMAP, NNTP, telnet, and other IP protocols HTML, MIME, base64, binhex, uuencode, and other internet data handling GUI development and multimedia services Unit testing, profiling, and documentation generation Restricted execution security option Availabl...
...data_received() and eof_received()). Datagram Transports Datagram transports have these methods: sendto(data, addr=None). Sends a datagram (a bytes object). The optional second argument is the destination address. If omitted, remote_addr must have been specified in the create_datagram_endpoint() call that created this transport. If present, and remote_addr was specified, they must match. The (data, addr) pair may be sent immediately or buffered. The return value is None. abort(). Immedi...
...data_received(self, fd, data): if fd == 1: reader = self.stdout elif fd == 2: reader = self.stderr else: reader = None if reader is not None: reader.feed_data(data) After updating to use the ?. operator: def pipe_data_received(self, fd, data): if fd == 1: reader = self.stdout elif fd == 2: reader = self.stderr else: reader = None reader?.feed_data(data) From asyncio/tasks.py: try: await waiter finally...
...data and nondata descriptors. The current implementation quite sensibly classifies member and getset descriptors as data (even if they are read-only!) and method descriptors as nondata. Non-descriptors (like function pointers or plain values) are also classified as non-data (!). This scheme has one drawback: in what I assume to be the most common case, referencing an instance variable stored in the instance dict, it does two dictionary lookups, whereas the classic scheme did a quick test for ...
...data for arbitrary "files" from the underlying storage backend, loader objects may supply a method named get_data(): loader.get_data(path) This method returns the data as a string, or raise IOError if the "file" wasn't found. The data is always returned as if "binary" mode was used - there is no CRLF translation of text files, for example. It is meant for importers that have some file-system-like properties. The 'path' argument is a path that can be constructed by munging module.__file__ (o...
...data stored in a bytes-like object without creating a temporary copy of the data into a string have been implemented in the past. The tofile and fromfile methods of the array object are good examples of this. The bytes object will support these methods too. However, pickling is useful in other situations - such as in the shelve module, or implementing RPC of Python objects, and requiring the end user to use two different serialization mechanisms to get an efficient transfer of data is undesir...
...data in the object and with the appropriate feedback mode. The string's length must be an exact multiple of the algorithm's block size or, in CFB mode, of the segment size. Returns a string containing the plaintext. encrypt(string) Encrypts a non-empty string, using the key-dependent data in the object, and with the appropriate feedback mode. The string's length must be an exact multiple of the algorithm's block size or, in CFB mode, of the segment size. Returns a string containing the ciph...
...data in result: if data: # don't send headers until body appears write(data) if not headers_sent: write('') # send headers now if body was empty finally: if hasattr(result, 'close'): result.close() Middleware: Components that Play Both Sides Note that a single object may play the role of a server with respect to some application(s), while also acting as an application with respect to some server(s). Such "middleware...
...data typing and very late binding Tight integration with C, C++, and Java modules May be compiled to Java byte code for use in any JVM String and regular expression processing Extensive XML and web services support HTTP, FTP, SMTP, POP, IMAP, NNTP, telnet, and other IP protocols HTML, MIME, base64, binhex, uuencode, and other internet data handling GUI development and multimedia services Unit testing, profiling, and documentation generation Available third party modules for database acc...
...data types. While this feature allows for quick and flexible code, it is the responsibility of the programmer to make explicit the data types that a function expects. A standard coding style that names variables according to their expected data type is an easy way to address this problem. A 30-day evaluation of Ultraseek 5.2 is available for download at http://www.verity.com/. About the Author Ryan Weisenberger is a software developer and project lead for Verity Ultraseek. He has been involved...
...data type, and Python is no exception. However, graphs are easily built out of lists and dictionaries. For instance, here's a simple graph (I can't use drawings in these columns, so I write down the graph's arcs): A -> B A -> C B -> C B -> D C -> D D -> C E -> F F -> C This graph has six nodes (A-F) and eight arcs. It can be represented by the following Python data structure: graph = {'A': ['B', 'C'], 'B': ['C', 'D'],...
...data-gpg-sig attribute on a file link with a value of either true or false to indicate whether or not there is a GPG signature. Repositories that do this SHOULD include it on every link. A repository MAY include a data-requires-python attribute on a file link. This exposes the Requires-Python metadata field, specified in PEP 345, for the corresponding release. Where this is present, installer tools SHOULD ignore the download when installing to a Python version that doesn't satisfy the requireme...