DOCS: Update documentation for the select expression.

Talk about the default being optional and what will happen
the field doesn't exist and no default is specified.
This commit is contained in:
Jeremy Wall 2019-03-01 17:15:07 -06:00
parent 40107cefb6
commit ecde7f4636

View File

@ -507,10 +507,11 @@ Conditionals
UCG supports a limited conditional expression called a select. A select UCG supports a limited conditional expression called a select. A select
expression starts with the `select` keyword and is followed by a an expression expression starts with the `select` keyword and is followed by a an expression
resolving to a string or boolean naming the field to select, an expression resolving to a string or boolean naming the field to select, an optional
resolving to the default value, and finally a tuple literal to select the field expression resolving to the default value, and finally a tuple literal to
from. If the field selected is not in the tuple then the default value will be select the field from. If the field selected is not in the tuple then the
used. default value will be used. If no default is specified then select will
throw a compile failure for the unhandled case.
``` ```
let want = "baz"; let want = "baz";
@ -527,7 +528,7 @@ select "quack", "quux", {
fuzz = "bang", fuzz = "bang",
}; // result will be "quux" }; // result will be "quux"
let ifresult = select true, NULL, { let ifresult = select true, {
true = "true result", true = "true result",
false = "false result", false = "false result",
}; // result will be "true result" }; // result will be "true result"