| unchecked | compiler directive |
Dangerous
| Description | OOT adds the concept of "unchecked" to Turing. Here, you can request that certain run time tests, which take place by default, can be eliminated. This makes the program more efficient at the risk of unreliability.
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| Example | Declare p to be an unchecked pointer to an integer (see pointers for details). Pointer p will be dangerous to use, because the run time system will not check to see if it actually locates an integer, as opposed to arbitrary computer memory. In other words, unchecked pointers are like C language pointers.
var p : unchecked ^ int |
| Example | Declare C to be an unchecked collection of records of type R (see collections for details). Pointers to C will be unchecked.
var C : unchecked collection of R |
| Example | Remove checking from the body of a loop.
for i : 1 .. 500
unchecked
if a ( i ) = key then
exit
end if
end for
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| Details | In the above example, the unchecked keyword requests that all checking, in particular, array bounds checking for array a, are to be omitted. The disabling lasts from the occurrence of the keyword unchecked to the end of the surrounding construct, in this case, until end for. In a similar way, the checked keyword will request that checking be re-enabled from the occurence of checked to the end of the surrounding construct. In the current (1999) implementation, the use of unchecked to turn off checking in a block of statements is ignored. In general, an implementation may choose to ignore requests to disable checking.
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