.net - How to prevent Scan from running multiple times? -

for example

var subject = new subject<int>(); var test = subject.scan(0, (x, y) => {     console.writeline("scan");     return x + 1; }); test.subscribe(x => console.writeline("subscribe1")); //test.subscribe(x => console.writeline("subscribe2")); observable.range(0, 1).subscribe(subject); console.writeline("done"); console.read(); 

the output is

scan subscribe1 done 

but if uncomment second subscribe output is

scan subscribe1 scan subscribe2 done 

why scan run 2 times , how can prevent it? output should

scan subscribe1 subscribe2 done 

i use subject accumulate different observables. use scan method update model , have different places need subscribe model updates. maybe there better solution without using subject?

try using observable.publish iconnectableobservable<t>.

var subject = new subject<int>(); var test = subject     .scan(0, (x, y) => {         console.writeline("scan");         return x + 1;     })     .publish(); test.subscribe(x => console.writeline("subscribe1")); test.subscribe(x => console.writeline("subscribe2")); test.connect(); observable.range(0, 1).subscribe(subject); console.writeline("done"); console.read(); 

output:

scan subscribe1 subscribe2 done 

publish turns cold scan observable hot observable begins emitting values when connect called.