AI Scripting Technical Details

if (FALSE and abc()) then
  ...
endif

That code would NOT call function abc() if the and operator short-circuts. In other words, since it is impossible for the statement to be true once the first half is false, the second half is skipped. Similarly, the or operator short-circuts if the first condition is true, skipping evaluating the second since that cannot make the statement false. That in a nutshell is short-circut evaluation.

Simple example, suppose I have stringlist and I need to search if it contains a specific string but only if I'm at war. Depending on short-circut evaluation I would write:

vars
  wars:   long
  value:  string
  list:   stringlist

...

// With short-circut evaluation:
if (wars > 0 and list.indexof(value) <> 0) then
  ...
endif

// Without short-circut evaluation:
if (wars > 0) then
  if (list.indexof(value) <> 0) then
    ...
  endif
endif

Just combining everything from above and some of my own research into the following answers:

Q: Do conditional operators (and, or) use short-circuit evaluation?

A: No.

--

Q: Is AND higher precedence than OR?

A: No. These operators are of the same precedence and parsed in strict left-to-right fashion.

--

Q: Can you have multiple exitwhen clauses in a loop?

A: Yes.

--

Q: Can you use a return statement to exit a function early?

A: No. The return statement only sets the value to eventually be returned. Return could be viewed as "set return_value := xxx" with each function having an implicit "return return_value" at the end.

--

Q: Any problems with not covering all the cases in a case statement? Is there even a default mechanism?

A: No. Uncovered cases do nothing. There is apparently no default case.

--

Q: Should lists be cleared before use?

A: No, at least the default SE5 scripts don't.

--

Q: Must locally declared lists be cleared prior to function exit?

A: No, at least the default SE5 scripts don't.

--

Q: Does Sys_AI_Setup_Select_Racial_Trait fail safely (does nothing) if the trait has already been added?

A: <...Research Pending...>

--

Q: Am I just missing it, or is Sys_Iifreal the only default trigraph function?

A: That appears to be the only one.

--

Q: Is there implicit type conversion from long to real? real to long?

A: No and No. All type convertions must be explicit.

--

Q: Is there some purpose I'm not seeing to the various operator simulating functions (Sys_Long_Add and such)?

A: No known reason.