Nothing stops me from implementing it, in fact it is VERY trivial to wrap member class methods onto a list subclass, and wrap functions to support vectorized behavior. The problem is that as soon as you hit anything outside your code that returns a list or iterator, everything gets blown away unless you explicitly wrap the return value, which entirely defeats the point.
On Fri, Dec 16, 2011 at 1:23 PM, Stefan Behnel <stefan...@behnel.de> wrote: > Nathan Rice, 16.12.2011 18:48: > >> I realize this has been discussed in the past, I hope that I am >> presenting a slightly different take on the subject that will prove >> interesting. This is primarily motivated by my annoyance with using >> comprehensions in certain circumstances. >> >> Currently, if you want to perform successive transformations on the >> elements of a list, a couple of options: >> >> 1. Successive comprehensions: >> >> L2 = [X(e) for e in L1] >> L3 = [Y(e) for e in L2] >> L4 = [Z(e) for e in L3] >> or >> L2 = [e.X() for e in L1] >> >> This gets the job done and gives you access to all the intermediate >> values, but isn't very succinct, particularly if you are in the habit >> of using informative identifiers. >> >> 2. One comprehension: >> >> L2 = [Z(X(Y(e))) for e in L1] >> or >> L2 = [e.X().Y().Z() for e in L1] >> >> This gets the job done, but doesn't give you access to all the >> intermediate values, and tends to be pretty awful to read. >> >> Having "typed" lists let you take preexisting string/int/etc methods >> and expose them in a vectorized context and provides an easy way for >> developers to support both vectors and scalars in a single function >> (you could easily "fix" other people's functions dynamically to >> support both). Additionally, "typed" lists/iterators will allow >> improved code analysis and optimization. The PyPy people have already >> stated that they are working on implementing different strategies for >> lists composed of a single type, so clearly there is already community >> movement in this direction. >> >> Just compare the above examples to their type-aware counterparts: >> >> L2 = X(L1) >> L2 = L1.X() >> >> L2 = Z(Y(X(L1))) >> L2 = L1.X().Y().Z() > > > What keeps you from implementing this? You don't need to change the language > for it, just wrap the list in a class that overrides __getattr__() to return > something that does the appropriate transformation for each element. I would > be surprised if you needed more than a couple of lines of Python code for > that. > > Stefan > > -- > http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
