swift - Call a static func on optional type -


i have protocol, conforming class , class 1 simple function.

protocol outputable {     static func output() }  class foo: outputable {     static func output() {         print("output")     } }  class bar {     func eat(_ object: anyobject?) {         if let object = object, let objecttype = type(of: object) as? outputable.type {             objecttype.output()         }     } }  let foo = foo() let bar = bar() var foooptional: foo? bar.eat(foo) // prints 'output' bar.eat(foooptional) // print nothing

is there way pass optional type being nil conforming outputable protocol , call protocol's static functions inside eat function? though it's nil still passing type , that's should need inside eat, right?

to make more clear. know why last line prints nothing. there way adjust eat print 'output' string out?

one of way achieve you're seeking use generics , call method on type: 

func eat<t: outputable>(_ object: t?) {     t.output() }

this work both foo , foo?


Comments

Post a Comment

Popular posts from this blog

python - What's the Pythonic way to report nonfatal errors in a parser? -

a parser created reads recorded chess games file. api used this: import chess.pgn pgn_file = open("games.pgn") first_game = chess.pgn.read_game(pgn_file) second_game = chess.pgn.read_game(pgn_file) # ... sometimes illegal moves (or other problems) encountered. pythonic way handle them? raising exceptions error encountered. however, makes every problem fatal, in execution stops. often, there still useful data has been parsed , returned. also, can not continue parsing next data set, because still in middle of half-read data. accumulating exceptions , raising them @ end of game. makes error fatal again, @ least can catch , continue parsing next game. introduce optional argument this: game = chess.pgn.read_game(pgn_file, parser_info) if parser_info.error: # appears quite verbose. # can @ least make best of sucessfully parsed parts. # ... are of these or other methods used in wild? actually, are fatal errors -- @ least, far being able repro...
Read more

sql server - Deadlock occuring in Clustered Columnstore index -

Image
we using clustered columnstore index in our transaction table holding order fulfillments. table regularly updated different sessions. but, every session specific order job number , so, not trying update same row @ same time. but, facing deadlock issues due below scenarios between sessions. row group locking & page lock row group locking & row group locking this not specific stored procedure. due multiple stored procedures updating table, sequentially 1 one, part of order fulfillment. the sample schema of table simple: create table orderfulfillments ( orderjobnumber int not null, fulfilledindividualid bigint not null, isindividualsuppressed bit not null, suppressionreason varchar(100) null ) i have given sample deadlock graph reference. please let me know, approach can take avoid deadlock situation. need clustered columnstore index in table, doing aggregation operations see how many times individual been fulfilled already. ...
Read more

php - curl: (35) OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to domain.com:443 -

i'm hitting curl on ubuntu terminal , getting response curl: (35) openssl ssl_connect: ssl_error_syscall in connection domain.com:443 . can't understand why happens. tried show curl's error number did not revert no. hitting server. below command : ./curl -i --tlsv1.2 -kv -h "content-type: application/xml" --verbose -x post --data /var/www/html/xml.xml --cacert /root/curl_ssl/curl-7.54.1/src/cert_org.crt domain.com/otp please suggest help.
Read more