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== Improved default value logic for Dictionaries == * The setdefault() method is badly named and poorly designed. In a typical call, d.setdefault.(k, []).append(v), the list may be unnecessarily instantiated and discarded on every call. At a minimum, default value should be a new empty list instead of None: d.setdefault(k).append(v). * A more versatile idea is to realize that defaults generalize to the whole dictionary instead of an individual lookup. A call to setdefault would then change the whole dictionary's behavior when a key is not found:: counts = {} counts.setdefault(value=0) for elem in data: counts[elem] += 1 index = {} index.setdefault(function=list) for pageno, page in enumerate(pages): for line in page: for word in line.split(): index[word].append(line) == Better boolean logic == The and/or operators should only return boolean values. This makes their use less error-prone, less prone to abuse, and more closely match other languages. Also, it will simplify the underlying bytecode which currently inserts many ''POP_TOP'' instructions to complete conditionals. The need to insert these instructions also results in extra code paths and jump instructions. Overall, the language will become more intuitive, more reliable, simpler, and faster. == Disallow calling class methods from instances == Calling with a instance is almost never what you want. When it is done, the results are not especially readable the code suggests that it is doing something that it isn't: {'a'=1}.fromkeys('poof') # what happened to 'a'? == Simplify the syntax for raising exceptions == * Eliminate string exceptions entirely. * Alway require instantation. IOW, prefer ''raise ValueError(dat)'' to ''raise ValueError, dat''. * Require that all exceptions subclass from ''Exception''. * Have ''Exception'' be a new-style class |
Other syntax ideas and feature ideas for Python 3.0.
Optional Static Typing / Adaptation
[http://www.artima.com/forums/flat.jsp?forum=106&thread=85551 Adding Optional Static Typing to Python] - article by Guido with responses
[http://groups-beta.google.com/group/comp.lang.python/messages/03553183983059e9,b505ef98e0436d24,dad1a48eee3248a4,7fac43f511f6bb21,ee614add572c34b1,7030280781fef1dc,6a852f4133c86be5,3a695733220ba136,4bec8d2fefbc0ce6,45b123013d82a365?thread_id=ff4df85e58d128bc&mode=thread&noheader=1&q=optional+static+typing#doc_03553183983059e9 "Adding static typing to Python" thread]
Lambda / Anonymous Methods / Closures
Suggested syntaxes:
- Many want to keep lambda instead of removing it in Python 3.0
- Anonymous Methods / Closures
[http://groups-beta.google.com/group/comp.lang.python/browse_frm/thread/81e17b1d3ccba538/41713ae1c0d7385a#41713ae1c0d7385a "Securing a future for anonymous functions in Python" thread]
http://logix.livelogix.com/tutorial/5-Standard-Logix.html#5.8 (uses same syntax as above except no multi-line support)
".." Sequences, Custom Infix Operators
[http://groups-beta.google.com/group/comp.lang.python/browse_frm/thread/6fb45278f4a24648/93ce3e9a08f5e4c7#93ce3e9a08f5e4c7 "Other notes" thread]
Improved default value logic for Dictionaries
- The setdefault() method is badly named and poorly designed. In a typical call, d.setdefault.(k, []).append(v), the list may be unnecessarily instantiated and discarded on every call. At a minimum, default value should be a new empty list instead of None: d.setdefault(k).append(v).
- * A more versatile idea is to realize that defaults generalize to the whole dictionary instead of an individual lookup. A call to setdefault would then change the whole dictionary's behavior when a key is not found
- counts = {} counts.setdefault(value=0) for elem in data:
- counts[elem] += 1
- for line in page:
- for word in line.split():
- index[word].append(line)
- for word in line.split():
- counts = {} counts.setdefault(value=0) for elem in data:
Better boolean logic
The and/or operators should only return boolean values. This makes their use less error-prone, less prone to abuse, and more closely match other languages. Also, it will simplify the underlying bytecode which currently inserts many POP_TOP instructions to complete conditionals. The need to insert these instructions also results in extra code paths and jump instructions. Overall, the language will become more intuitive, more reliable, simpler, and faster.
Disallow calling class methods from instances
Calling with a instance is almost never what you want. When it is done, the results are not especially readable the code suggests that it is doing something that it isn't: {'a'=1}.fromkeys('poof') # what happened to 'a'?
Simplify the syntax for raising exceptions
- Eliminate string exceptions entirely.
Alway require instantation. IOW, prefer raise ValueError(dat) to raise ValueError, dat.
Require that all exceptions subclass from Exception.
Have Exception be a new-style class