1 // Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information. 2 3 #pragma once 4 5 #if !defined(RXCPP_SOURCES_RX_CREATE_HPP) 6 #define RXCPP_SOURCES_RX_CREATE_HPP 7 8 #include "../rx-includes.hpp" 9 10 /*! \file rx-create.hpp 11 12 \brief Returns an observable that executes the specified function when a subscriber subscribes to it. 13 14 \tparam T the type of the items that this observable emits 15 \tparam OnSubscribe the type of OnSubscribe handler function 16 17 \param os OnSubscribe event handler 18 19 \return Observable that executes the specified function when a Subscriber subscribes to it. 20 21 \sample 22 \snippet create.cpp Create sample 23 \snippet output.txt Create sample 24 25 \warning 26 It is good practice to check the observer's is_subscribed state from within the function you pass to create 27 so that your observable can stop emitting items or doing expensive calculations when there is no longer an interested observer. 28 29 \badcode 30 \snippet create.cpp Create bad code 31 \snippet output.txt Create bad code 32 33 \goodcode 34 \snippet create.cpp Create good code 35 \snippet output.txt Create good code 36 37 \warning 38 It is good practice to use operators like observable::take to control lifetime rather than use the subscription explicitly. 39 40 \goodcode 41 \snippet create.cpp Create great code 42 \snippet output.txt Create great code 43 */ 44 45 namespace rxcpp { 46 47 namespace sources { 48 49 namespace detail { 50 51 template<class T, class OnSubscribe> 52 struct create : public source_base<T> 53 { 54 typedef create<T, OnSubscribe> this_type; 55 56 typedef rxu::decay_t<OnSubscribe> on_subscribe_type; 57 58 on_subscribe_type on_subscribe_function; 59 60 create(on_subscribe_type os) 61 : on_subscribe_function(std::move(os)) 62 { 63 } 64 65 template<class Subscriber> 66 void on_subscribe(Subscriber o) const { 67 68 on_exception( 69 [&](){ 70 this->on_subscribe_function(o); 71 return true; 72 }, 73 o); 74 } 75 }; 76 77 } 78 79 /*! @copydoc rx-create.hpp 80 */ 81 template<class T, class OnSubscribe> 82 auto create(OnSubscribe os) 83 -> observable<T, detail::create<T, OnSubscribe>> { 84 return observable<T, detail::create<T, OnSubscribe>>( 85 detail::create<T, OnSubscribe>(std::move(os))); 86 } 87 88 } 89 90 } 91 92 #endif 93
