Can only access global variables in my thread

[etixpp]

Sf::Thread can only access global variables in my project, but i think that should not be?
void RenderChunks();



In this example loadscreen can only be used if its declared out of main function.


int main(int argc, char **argv)
{
      // create a thread with RenderChunks() as entry point
      sf::Thread ChunkRenderThread(&RenderChunks);
      // run it
      ChunkRenderThread.launch();
return 1;
}
void RenderChunks()
{
   loadscreen = true;
   std::cout << "thread"<< std::endl;
   loadscreen = false;
}

[binary1248]

What kind of programming background do you have (if any) prior to C++? Because in almost all strongly-typed languages with a concept of automatic lifetime management (scopes, etc.) that I have seen, this is not possible. You declare an object in a scope and you use that object within that scope. Objects aren't implicitly shared between different scopes, hence you can't declare something in your main() and expect to be able to use it somewhere else. The global scope is of course the "super-scope" if you will, and all objects declared within it are naturally accessible everywhere where its declaration has effect. This is really really basic programming knowledge (not even specific to C++). If you have difficulties understanding this, you should try to learn a bit more about it before continuing.

[etixpp]

Ofc i know this lol, i was already wondering xD

I am just referring to the sf::Thread tutorial on the sfml site which says that it is possible.

->All the threads of a program share the same memory, they can access all the variables of the program.

This discription is just a bit confusing formulated then in combination with the example of mutex´es

[binary1248]

Can you quote the part that says this is possible? Because I can't find it...

Edit: That is just an explanation of what happens at the hardware level. Variable access is still constrained by the language. Of course if you hardcoded variables to be stored at specific addresses you could use them without an explicit name from all threads just by address, but sf::Thread doesn't magically override any language specifications. Any library written to conform to the language standard will never override any of its specifications. This is also common sense...

[AlexAUT]

Can you quote the part that says this is possible? Because I can't find it...

http://www.sfml-dev.org/tutorials/2.1/system-thread.php

At the subheadline "Protecting shared data" first sentence.



AlexAUT

[etixpp]

ye, sry, i was just a bit confused about this, can be closed then^^