Operating System Interaction

Trial offers a number of functions to interact with the operating system facilities in a portable fashion. Since this is more of a toolkit kind of thing, here's a list of relevant functions:

• data-root
  Returns the runtime directory of the game, which is either the executable directory in deployed mode, or the system source directory in dev mode.

• current-time
  Returns a monotonic clock in seconds as a double float. The precision is implementation defined, but may very well be higher than internal-real-time.

• open-in-browser
  Will open the given URL in a browser. This will also take care of using platform-specific browsers such as when Steam is used.

• open-in-file-manager
  Will open the given path in a file manager.

• envvar-directory
  Retrieve the directory described by an environment variable. May also return NIL if the variable is unset or empty.

• tempdir
  Return a path to the local system's temporary directory. Files in here may be deleted when the application exits, or when the system restarts.

• tempfile
  Return a path to a temporary file. Note: this function does not guarantee that the requested file does not already exist. Please use a loop over with-open-file.

• with-tempfile
  Binds path to a temporary file path according to tempfile and ensures the file is deleted when body exits.

• logfile
  Returns the path to the central Trial log file, typically stored next to the executable unless the environment variable TRIAL_LOGFILE is set.

• config-directory
  Returns the path to the directory to use to store configuration and save files. This can be configured through the environment variable TRIAL_CONFIG_HOME, AppData on Windows, and XDG_CONFIG_HOME everywhere else. The path is dependent on the +app-vendor+ and +app-system+.

• username
  Returns a descriptive name of the current user. This may be a human-readable display name of some sort, or their user account name. You may pass T to fetch the answer without the context of a main instance.

• io-bytes
  A monotonically increasing count of bytes read or written by the process.

• cpu-time
  A monotonically increasing floating point number of seconds of CPU time spent by the process.

• gpu-room
  Returns two values: the number of kilobytes of free VRAM, and the total number of kilobytes of VRAM.

• cpu-room
  Returns two values: the number of kilobytes of free RAM, and the total number of kilobytes of RAM.

• prevent-powersave
  Try to prevent the system from entering powersave mode or activating the screensaver. You must regularly call ping-powersave afterwards, and restore-powersave once you're done.