4Dv18 introduces the ability to use the debugger in compiled mode. This is done by executing a TRACE contained in 4DCODE tags through the PROCESS 4D TAGS command.

Below is a simple example:

C_TEXT($myCode_t;$output_t) $myCode_t:="<!--4DCODE TRACE\nC_DATE($myDate_d)\n$myDate_d:=Current Date-->" PROCESS 4D TAGS($myCode_t;$output_t)

$myCode contains:

TRACE C_DATE($myDate_d) $myDate_d:=Current Date

This will trigger the debugger to run in compiled mode and allow the variables to be examined in the expression pane.

However this feature is only applicable to non-preemptive processes. The TRACE command is marked as thread safe, this is because the command is appears to be ignored in a compiled preemptive process. The behavior causes the TRACE command to not do anything when this new feature is applied to a preemptive process.