![]() ![]() encoding if set otherwise, it's implicitly converted to str as per the above. This matter is unrelated to a variable's value but related to what you would see on the screen when it's printed - and whether you will get a UnicodeEncodeError when printing. implicitly) produces its repr() instead (which is only useful for debug printing), evading the encoding issue entirely bytes can only be decoded and str - encoded, and the encoding argument is mandatory.There's no "default encoding" at all: implicit conversion between str and bytes is now prohibited. when trying to encode() a str or decode() a unicode (the second third of the Stack Overflow questions).in string formatting (a third of UnicodeDecodeError/ UnicodeEncodeError questions on Stack Overflow are about this).So, for the purpose of transcoding, sys.getdefaultencoding() is the "string's default encoding".Ī decode() and encode() - with the default encoding - is done implicitly when converting strunicode: It is ascii (unless you uncomment a code chunk in site.py, or do some other hacks which are a recipe for disaster). In both cases, if the encoding is not specified, sys.getdefaultencoding() is used. unicode (Py2)/ str (P圓) - characters => can only be encoded.str (Py2)/ bytes (P圓) - bytes => can only be decoded (directly, that is details follow).In byte literals, non-ASCII characters are prohibited (such bytes must be specified with escape sequences), evading the issue altogether. (In particular, this makes it possible to have Unicode in identifiers.) Since all string literals are now Unicode, no additional transcoding is needed. Python 3 decodes the entire source file with the "source encoding" into a sequence of Unicode characters. Finally, if unicode_literals future is used, any regular string literals ( in that file only) are treated as Unicode literals when parsing, with all what that means. ![]() ![]() Same if there is a non-ASCII character in the file when there's no encoding specified. If the decoding fails, you will get a Synta圎rror. And Unicode strings will contain the result of decoding the file's bytes with the "source encoding". So, regular strings will contain the exact bytes that are in the file. ( It's more complicated than that under the hood, but this is the net effect.) > type t.py It only uses the "source encoding" to parse a Unicode literal when it sees one. A UTF-8 BOM has the same effect as a utf-8 encoding declaration. If not specified, the default is ascii for Python 2 and utf-8 for Python 3. Reading the source and parsing string literalsĪt the start of a source file, you can specify the file's "source encoding" (its exact effect is described later). See The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!) – Joel on Software to get the distinction. Decoding is translation from bytes to characters (Unicode or otherwise), and encoding (as a process) is the reverse. bytes (P圓) - none, printing produces its repr() insteadįirst of all, some terminology clarification so that you understand the rest correctly.encoding, always set and defaults to locale.getpreferredencoding() str (Py2) - not applicable, raw bytes are written.encoding if set, otherwise sys.getdefaultencoding() both (P圓) - none, must specify encoding explicitly when converting.there are implicit conversions which often result in a UnicodeDecodeError/ UnicodeEncodeError.both (Py2) - sys.getdefaultencoding() ( ascii almost always).bytes (P圓) - none, non-ASCII characters are prohibited in the literal.unicode (Py2)/ str (P圓) - "source encoding", defaults are ascii (Py2) and utf-8 (P圓).str (Py2) - not applicable, raw bytes from the file are taken.There are multiple parts of Python's functionality involved here: reading the source code and parsing the string literals, transcoding, and printing. ![]()
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