V Qc@sNdZdZdZdddYZdZedkrJendS( s Example of a generator: re-implement the built-in range function without actually constructing the list of values. OldStyleRange is coded in the way required to work in a 'for' loop before iterators were introduced into the language; using __getitem__ and __len__ . cCsyt|dkr,dt|ddfSt|dkr_t|dt|ddfSt|dkr|ddkrtdntd|DStdt|Wntk rtdnXd S( sgTake list of arguments and extract/create proper start, stop, and step values and return in a tupleiiiisstep argument must not be zerocss|]}t|VqdS(N(tint(t.0tx((s*/usr/lib64/python2.7/Demo/classes/Range.pys ss$range() accepts 1-3 arguments, givensArange() arguments must be numbers or strings representing numbersN(tlenRt ValueErrorttuplet TypeError(targlist((s*/usr/lib64/python2.7/Demo/classes/Range.pyt handleargss! cgsAt|\}}}|}x||kr<|V||7}qWdS(s,Function to implement 'range' as a generatorN(R(tatstarttstoptsteptvalue((s*/usr/lib64/python2.7/Demo/classes/Range.pytgenranges toldrangecBs2eZdZdZdZdZdZRS(sClass implementing a range object. To the user the instances feel like immutable sequences (and you can't concatenate or slice them) Done using the old way (pre-iterators; __len__ and __getitem__) to have an object be used by a 'for' loop. cGsEt|\|_|_|_td|j|j|j|_dS(s Initialize start, stop, and step values along with calculating the nubmer of values (what __len__ will return) in the rangeiN(RR R R tmaxR(tselfR ((s*/usr/lib64/python2.7/Demo/classes/Range.pyt__init__,scCsd|j|j|jfS(s-implement repr(x) which is also used by printsrange(%r, %r, %r)(R R R (R((s*/usr/lib64/python2.7/Demo/classes/Range.pyt__repr__2scCs|jS(simplement len(x)(R(R((s*/usr/lib64/python2.7/Demo/classes/Range.pyt__len__6scCs>d|ko|jknr1|j|j|StddS(simplement x[i]isrange[i] index out of rangeN(RR R t IndexError(Rti((s*/usr/lib64/python2.7/Demo/classes/Range.pyt __getitem__:s(t__name__t __module__t__doc__RRRR(((s*/usr/lib64/python2.7/Demo/classes/Range.pyR"s    c Cs9ddl}ddl}|jddd}ttddd}ttddd}||ksu||krtd|||fndGH|j}xtdD]}qW|j}xtdD]}qW|j}x|jdD]}qW|j} ||GdGH||Gd GH| |Gd GHdS( NiiidisEerror in implementation: correct = %s old-style = %s generator = %ssTimings for range(1000):issec (old-style class)ssec (generator)ssec (built-in)(ttimet __builtin__trangetlistRRt Exception( RRtcorrect_resulttoldrange_resulttgenrange_resulttt1Rtt2tt3tt4((s*/usr/lib64/python2.7/Demo/classes/Range.pyttestBs*      t__main__N((RRRRR'R(((s*/usr/lib64/python2.7/Demo/classes/Range.pyts