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| -rw-r--r-- | source/rainerscript/expressions.rst | 25 |
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diff --git a/source/rainerscript/expressions.rst b/source/rainerscript/expressions.rst new file mode 100644 index 0000000..a3f6060 --- /dev/null +++ b/source/rainerscript/expressions.rst @@ -0,0 +1,25 @@ +Expressions +=========== + +The language supports arbitrary complex expressions. All usual operators +are supported. The precedence of operations is as follows (with +operations being higher in the list being carried out before those lower +in the list, e.g. multiplications are done before additions. + +- expressions in parenthesis +- not, unary minus +- \*, /, % (modulus, as in C) +- +, -, & (string concatenation) +- ==, !=, <>, <, >, <=, >=, contains (strings!), startswith (strings!) +- and +- or + +For example, "not a == b" probably returns not what you intended. The +script processor will first evaluate "not a" and then compare the +resulting boolean to the value of b. What you probably intended to do is +"not (a == b)". And if you just want to test for inequality, we highly +suggest to use "!=" or "<>". Both are exactly the same and are provided +so that you can pick whichever you like best. So inequality of a and b +should be tested as "a <> b". The "not" operator should be reserved to +cases where it actually is needed to form a complex boolean expression. +In those cases, parentheses are highly recommended. |