Qt Signal Slot Mapper

• Qt Signal Slot Mapper Tool
• Qt Signal Slot Performance
• Qt Signal Slot Mapper Bot

Today we will learn about a variation of the Observer design patternthat is used prominently within Qt, called signals and slots.

As you can see the macros used in header files for signals are defined as public. As for the explicit statet public,private,protected directives, these are ignored in the signals section. Prior 5.0 versions of QT have signals defined as protected. Those were still available for connections using the SIGNAL macro. The slots macro # define slots. First, motivation for its existence: while Qt's signal/slot mechanism generally works fine and dandy, sometimes there are some roadkill/missing information during those signal/slot transits. What I mean, your slot function in your code, to work properly perhaps needs some extra stuff that the Qt standard signals do not supply.

• Observer and Publish/Subscribe Pattern
• Observers as callback functions
• Observers using signals
• Qt signals
• Examples
• Exercise

Qt Signal Slot Mapper Tool

GitHub Invitation URL:exercise13

Steps:

1. Clone the assignment for today after accepting the GitHubinvitation at the link above. The repository contains four files:

• traffic_light.h defines a Qt widget that uses three radio buttons tosimulate a traffic light.
• traffic_light.cpp is the implementation of the traffic light
• main.ccp sets up the application and starts the event loop
• CMakeLists.txt is the build configuration for the example

2. Add code to the TrafficLight class to add a slot called toggle tochange the light currently lit. The sequence should gored->green->yellow->red repeating after that. You will need to addsome internal members to the TrafficLight class to accomplish this.
3. Read the documentation forQTimer and, in the mainfunction of main.cpp, add code to setup and start a timer thatgoes off every one second, resulting in the traffic light beingtoggled. This will require connecting a signal from the timer to theslot implemented in step 2.
4. Build and run your application. Does the light change in the correctsequence?
5. Now, use git to commit the source files changed to the localrepository.
6. Use git push to synchronize the repository with that onGitHub.
7. Finally, post the screenshot of output of your program to Canvas.

Qt Signal Slot Performance

Qt Signal Slot Mapper Bot

You have completed the Exercise.