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← Revision 4 as of 2005-01-03 03:54:54 → ⇥
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Editor: pool-68-160-34-147
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Deletions are marked like this. Additions are marked like this.
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 * 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).  * 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) }}}.
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{{{
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}}}
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many ''POP_TOP'' instructions to complete conditionals. The need to insert these instructions also results in extra many {{{POP_TOP}}} instructions to complete conditionals. The need to insert these instructions also results in extra
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suggests that it is doing something that it isn't: {'a'=1}.fromkeys('poof') # what happened to 'a'? suggests that it is doing something that it isn't:
{{{
{'a'=1}.fromkeys('poof') # what happened to 'a'?  }}}
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 * Alway require instantation. IOW, prefer ''raise ValueError(dat)'' to ''raise ValueError, dat''.  * Alway require instantation. IOW, prefer {{{raise ValueError(dat)}}} to {{{raise ValueError, dat}}}.
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The current implementation will call __iadd__(), allowing it to do the in-place change, but then require that the method return the new value and then store it again. Ideally, all the responsibility for the update should lie with the __iadd__() method and it should return None. This simplifies the bytecode and eliminates some annoying behavior (such as a[0]+=1 succeeding '''and''' raising an error when a=([0],)). The current implementation will call {{{__iadd__()}}}, allowing it to do the in-place change, but then require that the method return the new value and then store it again. Ideally, all the responsibility for the update should lie with the {{{__iadd__()}}} method and it should return None. This simplifies the bytecode and eliminates some annoying behavior (such as {{{a[0]+=1}}} succeeding '''and''' raising an error when {{{a=([0],)}}}.

Other syntax ideas and feature ideas for Python 3.0.

TableOfContents()

Optional Static Typing / Adaptation

Lambda / Anonymous Methods / Closures

Suggested syntaxes:

".." Sequences, Custom Infix Operators

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

Fix implementation of in-place operators

The current implementation will call __iadd__(), allowing it to do the in-place change, but then require that the method return the new value and then store it again. Ideally, all the responsibility for the update should lie with the __iadd__() method and it should return None. This simplifies the bytecode and eliminates some annoying behavior (such as a[0]+=1 succeeding and raising an error when a=([0],).

Remove the distinction between data and non-data decriptors

Having the distinction provides a tiny benefit but incurs a large cost in terms of implementation complexity and increasing the learning curve for descriptors. Using the presence or absence of a setter to distinquish the two is somewhat hackish and confuses the heck out of anyone first trying to master descriptors. Even after using descriptor for a while, that nuance remains an annoying distraction.

Python3.0Suggestions (last edited 2010-05-16 23:17:52 by modemcable054)

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