How to use the callbackHandler inside the library #107

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1. fhessel

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   on Dec 15, 2020
2. fhessel commented on Dec 15, 2020

   

   fhessel

   on Dec 15, 2020

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   Hi,

   it's the same issue as in #90 or #105: If you want to use a method from a class, you need to somehow specify on which instance that method should be called. You can do such things with std::bind, but in 1.0.0, you cannot pass the result from that to the ResourceNode.

   If you need that functionality now, switch from master to PR #91 as mentioned in this comment and use std::bind like described here. I will try to keep up with PR/Issues during holidays.
3. robertgregor commented on Dec 15, 2020

   

   robertgregor

   on Dec 15, 2020

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   Hi, Yes, this I did: esp32_https_server-feature-functional-callbacks.
   But how can use std::bind?
   I have tried this:
   HTTPSCallbackFunction handler = std::bind(&RemoteHome::handleSPIFFS, std::placeholders::_1);
   server->registerNode(new ResourceNode("/", "GET", handler));

   But I have this error:
   c:\users\gregorro\appdata\local\arduino15\packages\esp32\tools\xtensa-esp32-elf-gcc\1.22.0-80-g6c4433a-5.2.0\xtensa-esp32-elf\include\c++\5.2.0\functional:1426:7: error: static assertion failed: Wrong number of arguments for pointer-to-member
   static_assert(_Varargs::value
   ^
   C:\RH\Sources\RH\RemoteHomeArduinoSketches\WiFi_ESP32\libraries\RemoteHome\src\RemoteHome.cpp: In member function 'void RemoteHome::startWebServer()':
   C:\RH\Sources\RH\RemoteHomeArduinoSketches\WiFi_ESP32\libraries\RemoteHome\src\RemoteHome.cpp:790:20: error: conversion from 'std::_Bind_helper<false, void (RemoteHome::)(httpsserver::HTTPRequest, httpsserver::HTTPResponse*), const std::_Placeholder<1>&>::type {aka std::_Bind<std::_Mem_fn<void (RemoteHome::)(httpsserver::HTTPRequest, httpsserver::HTTPResponse*)>(std::_Placeholder<1>)>}' to non-scalar type 'httpsserver::HTTPSCallbackFunction {aka std::function<void(httpsserver::HTTPRequest*, httpsserver::HTTPResponse*)>}' requested
   std::bind(&RemoteHome::handleSPIFFS, std::placeholders::_1);
4. fhessel commented on Dec 15, 2020

   

   fhessel

   on Dec 15, 2020

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   You need to stick to the exact syntax from the other PR.

   Somewhere outside any function:

   // Create a global instance of the RemoteHome class
   RemoteHome myRemoteHome;

   In your setup() or whereever you configure your server:

   HTTPSCallbackFunction handler =
             std::bind(&RemoteHome::handleSPIFFS, &myRemoteHome, std::placeholders::_1, std::placeholders::_2);
   server.registerNode(new ResourceNode("/", "GET", handler));

   The first parameter of std::bind specified the function that should be called. The second parameter is a pointer to the instance on which it should be called (you also need to create such an instance, and make sure that it's valid for the whole lifetime of the server. That's why we created it in global scope above). The third and fourth parameters are placeholders. They will become the req and res parameter of the bound function. Since we have two parameters, you need to have two placeholders.
5. robertgregor commented on Dec 15, 2020

   

   robertgregor

   on Dec 15, 2020

   Last edited by robertgregor

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   OKi, yes, shall be like that:
   HTTPSCallbackFunction handler =
   std::bind(&RemoteHome::handleSPIFFS, this, std::placeholders::_1, std::placeholders::_2);

   Thanks!!!