Hello all, For better or for worse, I have created a patch against the py3k trunk which introduces a binary operator '@' as an alternative syntax for the new string formatting system introduced by PEP 3101 ("Advanced String Formatting"). [1] For common cases, this syntax should be as simple and as elegant as its deprecated [2] predecessor ('%'), while also ensuring that more complex use cases do not suffer needlessly. I would just like to know whether this idea will float before submitting the patch on Roundup and going through the formal PEP process. This is my first foray into the internals of the Python core, and with any luck, I did not overlook any BDFL proclamations banning all new binary operators for string formatting. :-) QUICK EXAMPLES >>> "{} {} {}" @ (1, 2, 3) '1 2 3' >>> "foo {qux} baz" @ {"qux": "bar"} 'foo bar baz' One of the main complaints of a binary operator in PEP 3101 was the inability to mix named and unnamed arguments: The current practice is to use either a dictionary or a tuple as the second argument, but as many people have commented ... this lacks flexibility. To address this, a convention of having the last element of a tuple as the named arguments dictionary is introduced. >>> "{} {qux} {}" @ (1, 3, {"qux": "bar"}) '1 bar 3' Lastly, to print the repr() of a dictionary as an unnamed argument, one would have to append an additional dictionary so there is no ambiguity: >>> "{}" @ {"foo": "bar"} Traceback (most recent call last): File "<stdin>", line 1, in <module> IndexError: tuple index out of range >>> "{}" @ ({"foo": "bar"}, {}) "{'foo': 'bar'}" Admittedly, these workarounds are less than clean, but the understanding is the '@' syntax would indeed be an alternative, so one could easily fall back to the str.format() method or the format() function. IMPLEMENTATION Code-wise, the grammar was edited per PEP 306 [3], and a function was introduced in unicodeobject.c as PyUnicode_FormatPrime (in the mathematical sense of A and A' -- I didn't fully understand or want to intrude upon the *_FormatAdvanced namespace). The PyUnicode_FormatPrime function transforms the incoming arguments, i.e. the operands of the binary '@', and makes the appropriate do_string_format() call. Thus, I have reused as much code as possible. I have done my development with git by using two branches: 'master' and 'subversion', the latter of which can be used to run 'svn update' and merge back into master. This way my code changes and the official ones going into the Subversion repository can stay separate, meanwhile allowing 'svn diff' to produce an accurate patch at any given time. The code is available at: http://github.com/jcsalterego/py3k-atsign/ The SVN patch [4] or related commit [5] are good starting points. References: [1] http://www.python.org/dev/peps/pep-3101 [2] http://docs.python.org/3.0/whatsnew/3.0.html [3] http://www.python.org/dev/peps/pep-0306/ [4] http://github.com/jcsalterego/py3k-atsign/blob/master/py3k-atsign.diff [5] http://github.com/jcsalterego/py3k-atsign/commit/5c8bdf72d9252cea78af2b78096... Thanks, -- Jerry Chen