Can threads safely read variables set by VCL events?
- by Tom1952
Is it safe for a thread to READ a variable set by a Delphi VCL event?
When a user clicks on a VCL TCheckbox, the main thread sets a boolean to the checkbox's Checked state.
CheckboxState := CheckBox1.Checked;
At any time, a thread reads that variable
if CheckBoxState then ...
It doesn't matter if the thread "misses" a change to the boolean, because the thread checks the variable in a loop as it does other things. So it will see the state change eventually...
Is this safe? Or do I need special code? Is surrounding the read and write of the variable (in the thread and main thread respectively) with critical code calls necessary and sufficient?
As I said, it doesn't matter if the thread gets the "wrong" value, but I keep thinking that there might be a low-level problem if one thread tries to read a variable while the main thread is in the middle of writing it, or vice versa.
My question is similar to this one: http://stackoverflow.com/questions/1353096/cross-thread-reading-of-a-variable.
(Also related to my previous question: http://stackoverflow.com/questions/2449183/using-entercriticalsection-in-thread-to-update-vcl-label)
