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Compatibility

How compatible with Lua is Pluto?​

Pluto is 99.9% compatible with most Lua source code. However, it's imperfect. Due to that, Pluto implements several compatibility macros.

Where are the incompatibilities?​

Pluto adds the following reserved tokens:

  • switch
  • continue
  • enum
  • new
  • class
  • parent
  • export

Which means you can't use them as variable names or for function calls. They can still be used with short-hand table indexes and goto labels though, because Pluto removes the restriction from them.

Compatibility Mode​

Compatibility mode is a per-keyword option that adds a pluto_ prefix. For example, switch becomes pluto_switch under compatibility mode. However, when compatibility mode is disabled, the pluto_ syntax is still valid. This project has high regard for smooth migration paths.

Configuration for scripters​

You can change the meaning of Pluto's reserved tokens at any point in your scripts by using pluto_use.

  • pluto_use * = false, switch enables compatibility mode for all keywords except for switch.
    • pluto_use * = false enables compatibility mode for all keywords.
    • pluto_use switch disables compatibility mode for the switch keyword.
      • pluto_use switch = true would be another way of writing this.
  • pluto_use "0.2.0" enables compatibility mode for all keywords except for: switch, continue
  • pluto_use "0.5.0" enables compatibility mode for all keywords except for: switch, continue, enum
  • pluto_use "0.6.0" enables compatibility mode for all keywords except for: switch, continue, enum, new, class, parent, export

Configuration for integrators​

The macros for compatibility mode are well-documented, and found inside your luaconf.h file.

Portability & proactive compatibility​

We recommend scripters place a pluto_use statement at the beginning of their scripts for two reasons:

  • Portability. This will override the compatibility mode settings compiled into Pluto so your script will be parsed identically in all Pluto environments.
  • Proactive compatibility. Any keywords added by future versions of Pluto will also be put in compatibility mode by these statements, so in the off-chance your script uses a future reserved keyword as a variable name, it would still parse as you intended when you wrote it.

Plus, it's as simple as pluto_use "0.6.0" or pluto_use "0.5.0" — see "Configuration for scripters" above.