control structure
always
You can use always to identify code that will run regardless of whether a throw
occurs.
The always keyword begins a block of code—known as a clause—that will be executed at
the end of a lexical scope. Only a halt-everything will cause the always clause not to be
executed. The code in the always clause is executed at the end of the scope, even if a something occurs
which would otherwise cause the scope to terminate. The always clause will be executed even if you
exit the scope with a throw, return, exit, or halt.
The always clause must be the last clause in a lexical scope, occurring after any catch
clauses in the scope. In this example, the reopen action will throw to
#external-exception if main-log is not initialized.
include "omdate.xin" global stream main-log ; This should be set from command-line. process local stream log-stream reopen log-stream as file main-log put log-stream "The program ran at: " || date "=xY-=M-=D =h:=m:=s" || "%n" catch #program-error output "Something went wrong. Don't know what it was.%n" always put #error "The program terminated at: " || date "=xY-=M-=D =h:=m:=s" || "%n"
You may want to include more than one always clause in a scope. If an error or throw occurs in
an always clause, the rest of that block will not be executed, but a subsequent always clause
in the same scope will be executed. This allows you to make sure that each always operation is executed,
even if there is an error in executing a previous one.
When a throw to catch-name is initiated in a nested scope and caught at an outer level of
nesting, code is executed in the following sequence:
always clauses in the scope of the throw, in the order they appear,
always clauses in intermediate scopes between the throw and the catch
catch-name, in the order they appear,
catch clause of catch-name, and finally
always clauses in the scope of the catch catch-name, in the order in
which they appear.