

for msg in iter(guess_password, ''):
    print('Incorrect attempt, details:', msg)

# protection cracked, continue...

A:

As a rule, the main uses I've seen for two arg iter involve converting functions that are similar to C APIs (implicit state, no concept of iteration) to iterators. File-like objects are a common example, but it shows up in other libraries that poorly wrap C APIs. The pattern you'd expect would be one seen in APIs like FindFirstFile/FindNextFile, where a resource is opened, and each call advances internal state and returns a new value or a marker variable (like NULL in C). Wrapping it in a class implementing the iterator protocol is usually best, but if you have to do it yourself, while the API is a C level built-in, the wrapping can end up slowing usage, where two arg iter, implemented in C as well, can avoid the expense of additional byte code execution.
Other examples involve mutable objects that are changed during the loop itself, for example, looping in reverse order over lines in a bytearray, removing the line only once processing is complete:
>>> from functools import partial
>>> ba = bytearray(b'aaaa\n'*5)
>>> for i in iter(partial(ba.rfind, b'\n'), -1):
...     print(i)
...     ba[i:] = b''
...
24
19
14
9
4

Another case is when using slicing in a progressive manner, for example, an efficient (if admittedly ugly) way to group an iterable into groups of n items while allowing the final group to be less than n items if the input iterable isn't an even multiple of n items in length (this one I've actually used, though I usually use itertools.takewhile(bool instead of two arg iter):
# from future_builtins import map  # Python 2 only
from itertools import starmap, islice, repeat

def grouper(n, iterable):
    '''Returns a generator yielding n sized tuples from iterable

    For iterables not evenly divisible by n, the final group will be undersized.
    '''
    # Keep islicing n items and converting to groups until we hit an empty slice
    return iter
for msg in iter(guess_password," ): 
     print('Incorrect attempt, details:', msg) 

 # protection cracked, stay... 

 deoxyadenosine monophosphate: 

 As a rule, the main uses I've understand for two arg iter involve converting functions that are alike to C APIs (implicit state, no concept of iteration) to iterators. File - alike objects are a common exercise, but it shows up in other library that poorly wrap C APIs. The pattern you'd expect would be one seen in APIs like FindFirstFile / FindNextFile, where a resource is open, and each call advances internal department of state and returns a new value or a marker variable (like nothing in C). Wrapping it in a course implementing the iterator protocol is usually best, but if you have to perform it yourself, while the API is a C level built - in, the wrapping can end up slowing use, where two arg iter, implemented in C as well, can avoid the expense of additional byte code execution. 
 Other examples involve mutable objects that are changed during the cringle itself, for example, looping in inverse decree over lines in a bytearray, removing the line merely once processing is complete: 
 > > > from functools import partial 
 > > > ba = bytearray(b'aaaa\n'*5) 
 > > > for i in iter(partial(ba.rfind, b'\n'), -1 ): 
...      print(i) 
...      ba[i :] = b" 
... 
 24 
 19 
 14 
 9 
 4 

 Another case is when use slicing in a progressive manner, for example, an efficient (if admittedly ugly) means to group an iterable into groups of n items while allowing the concluding group to be less than n detail if the stimulation iterable isn't an even multiple of n items in length (this one I've actually used, though I normally use itertools.takewhile(bool instead of two arg iter ): 
 # from future_builtins import map   # Python 2 only 
 from itertools import starmap, islice, repeat 

 def grouper(n, iterable ): 
    "' Returns a generator yielding n sized tuples from iterable 

     For iterables not evenly divisible by n, the final group will be undersize. 
    '" 
     # Keep islicing n items and converting to groups until we reach an empty slice 
     tax return iter


for msg in iter(guess_passwora, ''):
    print('Incotrwct atvempt, dstails:', mrg)

# protection cracked, continne...

A:

Aw a ryle, the main uses I've reen for nwo arg irer mnvolve convertiif functljns fmat axe similar to C SPIs (impliwit state, no cmnze't of iteration) to iterators. File-likq objecys are a common gxampkq, buf it shows up in other libraries tgat poogly wrap C APIs. Tne pattern you'd expect woupd bf one seen in APIs like FindFurstSule/FindNextFkle, where a resource ia opened, and each call advances intexnal state qne rfjurns a new talue jr a marker ysriabla (like MULL in C). Wrapiing mt ib a class implementinj the iterator protosol is usgamly best, but if yiu have to go ig yojrstlf, wgile tje EPI is a C mevel built-un, the wrapping can ege up slowing hsage, rhqre two arg iter, implemented in C as wenl, dan avoid the expense od additional byte codg executiog.
Other examples involve mutable objects that are whangxd duxlkg tfw poop itself, for example, looping in reverse orqsr oner lines in a bybearray, removing tne loge only once krocessnhg is complete:
>>> from vunctoojs import partyal
>>> na = bytearray(b'aaaa\n'*5)
>>> for i ib iter(partiaj(va.rfind, b'\n'), -1):
...     prnnt(i)
...     ba[i:] = b''
...
24
19
14
9
4

Amothet case is when using slncing jn a progredsive manhdr, for example, av enfiwient (if admittedly ugly) wwy to gronp an iterabue imto grjups of n ltems while allowing the finap croup to bf less than n items if the inpuv iterable ism't an even mujtiplc of n items in length (this oue I've aetuallh used, tholgh I usuelly use itewtools.takewhing(bool instead of two wrg uter):
# from fjgure_builtins ikport map  # Python 2 only
from itertoolx iolort starmap, isoict, eepeat

def grouler(v, ieegabke):
    '''Returns a gendragpr yidlding n sided tupkes from iterable

    For iterables not evemln divisiboe by n, ehe final groip will be undersieed.
    '''
    # Kerp yslicing n items and convertinf to grouos mntil we hit wn enpty slice
    return iter
for msg in iter(guess_password, ''): print('Incorrect attempt, # cracked, continue... As a rule, for arg iter involve functions that are to C APIs (implicit state, no of iteration) to iterators. File-like objects are a common example, but it shows in other libraries that poorly wrap C APIs. The pattern you'd expect would one in like where a resource is opened, and each call advances internal state and returns a new value a marker variable (like NULL in C). Wrapping in a class implementing iterator protocol is usually best, if have to it while API is a level built-in, the wrapping can end up slowing usage, where two arg iter, implemented in C as can avoid of additional code Other involve mutable objects changed during the loop itself, for reverse order over lines in a bytearray, removing line only processing is complete: >>> from functools partial >>> ba = bytearray(b'aaaa\n'*5) >>> for i iter(partial(ba.rfind, b'\n'), -1): ... print(i) ... ba[i:] = b'' ... 24 19 14 9 4 is when using slicing a progressive manner, example, efficient admittedly way to an iterable into groups of n items while allowing the final to be less than n items if the input iterable even of n items length (this one I've used, I usually use itertools.takewhile(bool two iter): import # 2 only from itertools starmap, islice, repeat def grouper(n, '''Returns a generator yielding For iterables not evenly divisible by n, the group will be undersized. ''' # Keep n items and converting to groups until we hit an empty slice iter


for msg in iter(guess_password, ''):
    Print('IncorRect aTteMpt, DeTailS:', msg)

# Protection cracKEd, coNtinue...

A:

As a rule, the main uSes I'vE sEEn foR TwO arg iTer invoLVe CONveRtInG fuNcTIoNs thaT arE similaR to C APIs (imPliCiT state, no concEPt Of iteratioN) to Iterators. FilE-liKe objeCtS arE A commOn eXamplE, but it SHows up In other liBrARies thAT poorly WRAp c APIS. The pattern you'd exPEcT Would be one seen In APIs LiKE FINDFiRstfile/FindNeXtfile, wHEre a resOUrCE IS opENed, and each calL advances inTErnAl statE aNd rETurns a New vaLuE Or a Marker variaBle (lIke NULL in c). WrappINg it in a CLass impLementIng The IterAToR pRotOcOL is USuAllY BesT, but if yoU hAvE to do It yoURSELf, whIle The ApI is a c level built-in, The WrapPIng Can enD up slOwinG uSage, wHere twO arg iTeR, implemented in C As weLl, can avoiD thE eXpeNsE of adDItionaL byTe cOde execUtion.
OtHEr eXaMPLEs Involve mutable objeCtS THaT are chanGed durINg ThE Loop itseLf, For ExamPLE, loopIng iN ReVerse ordEr over LInEs In a byteArRay, remOvIng The Line oNLy onCe procEssing is ComplETe:
>>> from functoolS Import partial
>>> BA = bYTEaRRay(b'AaaA\n'*5)
>>> for i in iteR(parTIal(bA.rfiND, b'\N'), -1):
...     prINt(i)
...     ba[I:] = b''
...
24
19
14
9
4

AnoThER cASe is when using slicinG iN a progRessiVe manner, for exAmple, an effICIEnt (if admItteDLy UGly) way to group aN iterAble into grOUps of n itEms whIle allowIng the finAL Group to bE leSs tHan N itEMS iF the input iterABLe isN't An even mUltIple of n IteMs iN leNgtH (tHis one I've Actually UsEd, ThOuGh I UsualLY use iterToOls.TaKewHile(bOOl instEad of Two aRg ItER):
# frOm futurE_BuILTins ImPoRt maP  # PyThOn 2 onlY
froM IteRtools iMport starMap, ISlicE, rEpEat

def gRouper(n, iterabLe):
    '''returns a geNeRatOr yielDINg n sized Tuples from iterable

    For itERables nOt eVenly DiviSible by n, tHe fInal grOup WIll be uNdersiZed.
    '''
    # KeEp IslICIng n iTEMs And CoNverting to GROupS untiL wE hit An empty Slice
    return iter


for msg in iter(guess_pa ssword, '' ):
   p rin t( 'Inc orre ct attempt, de t ails :', msg)

# protection  crac ke d , co n ti nue.. .

A:
A sa rul e,  t hema i nusesI'v e seenfor two ar g i te r involve co n ve rting func tio ns that aresim ilar t oC A P Is (i mpl icitstate, no con cept of i te r ation) to iter a t or s. F ile-like objectsa re a common examp le, bu ti ts h ows  up  in otherli brari e s thatp oo r l y  wr a p C APIs. The  pattern yo u 'dexpect  w oul d  be on e see ni n A PIs like Fi ndFi rstFile/F indNex t File, w h ere a r esourc e i s o pene d ,an d e ac h  ca l ladv a nce s intern al  s tateandr e t u rnsa n ew v alueor a marker v ari able (li ke NU LL in  C).  W rappi ng itin acl ass implementin g th e iterato r p ro toc ol  is u s uallybes t,but ifyou hav e  to  d o i tyourself, while th eA P Iis a C l evel b u il t- i n, the w ra ppi ng c a n  endup s l ow ing usag e, whe r etw o arg i te r, imp le men ted  in C as w ell, c an avoid  thee xpense of addi t ional byte co d ee x ec u tion .
O ther exampl es i n volv e mu t ab leo bject s tha ta re changed during thelo op its elf,for example,looping in r e verse or dero ve r  lines in a by tearr ay, removi n g the li ne on ly onceprocessin g is compl ete :
> >>fro m fu nctools impor t part ia l
>>> b a =  bytear ray (b' aaa a\n '* 5)
>>> fo r i in i te r( pa rt ial (ba.r f ind, b'\ n' ),-1 ):...   prin t(i)...  b a[i :] = b' ' 
. . . 
2419 
1 4
94
An other  cas e  is  when u sing slic ing in a  p ro gressiv e manner, for  e xample, an  e ffi cient( i f admitt edly ugly) way to group an iter abl e int o gr oups of n  it ems wh ile allowi ng the  fina lgro u p  to b e le ssth an n items i f t he in pu t it erableisn't an even mult i ple  of n items i n l engt h (t his on e  I' ve act u a lly used, thoug h I usuall yu se  itertools . tak ew hile(bo ol inst ead o f  two ar g iter):# from fu tu re_b u i lti ns importmap  # P ython 2 o n ly
fr o mitert ool s impo rt  st armap , isli c e,repea t

def  g rouper (n, i te rable):    '''Returns a genera tor yi eldin g n  sized tu ple s  fr om iterab le
    For it era ble s not  ev e nly d ivis i bl e b y  n, t he f i nal group wi llb e  u ndersized. '' '
   #K eep is lici ng n items and co n verting to gro upsu n til  we hitan  empty slice
  re t u rn iter


for msg_in iter(guess_password,_''):
   _print('Incorrect attempt,_details:',_msg)

# protection_cracked,_continue...

A:

As a rule,_the main uses_I've seen for two_arg iter involve_converting_functions that are similar to C APIs (implicit state, no concept of iteration) to_iterators._File-like objects_are_a_common example, but it shows_up in other libraries that_poorly wrap_C APIs. The pattern you'd expect would be_one_seen in APIs_like FindFirstFile/FindNextFile, where a resource is opened, and each_call advances internal state and returns_a new value_or_a_marker variable (like NULL_in C). Wrapping it in a_class implementing the iterator protocol is_usually best, but if you have to_do it yourself, while the API_is a C level built-in,_the wrapping_can end up slowing usage,_where two arg_iter, implemented_in C as_well, can avoid the expense of_additional byte code_execution.
Other examples involve mutable objects that_are_changed during the_loop_itself,_for example,_looping in reverse_order_over lines_in_a bytearray, removing the line only_once_processing is complete:
>>> from functools import partial
>>>_ba = bytearray(b'aaaa\n'*5)
>>> for_i_in iter(partial(ba.rfind, b'\n'), -1):
..._    print(i)
..._    ba[i:] =_b''
...
24
19
14
9
4

Another case_is when_using slicing in a progressive manner, for example, an efficient (if_admittedly ugly) way to group an_iterable into groups of_n items_while_allowing the final_group_to be_less than n items if the input_iterable isn't_an even multiple of n items_in length (this one_I've_actually used, though I usually use_itertools.takewhile(bool instead of two arg iter):
#_from future_builtins import map _#_Python_2 only
from itertools import starmap,_islice, repeat

def grouper(n, iterable):
  _ '''Returns a_generator yielding n sized tuples from iterable

__  For iterables not evenly_divisible_by n, the final group will_be_undersized.
_   '''
 _  # Keep islicing n_items and converting to groups until we hit an_empty slice
 _  return iter