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Assertions: Difference between revisions
D entry rewritten and completed
(D entry rewritten and completed) |
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</pre>
=={{header|D}}==
int foo(in bool condition) pure nothrow
▲<lang d>import std.string;
in {
void main() {▼
// Assertions are used in contract programming.
assert(
} out(result) {
assert(result > 0);
} body {
if (condition)
return 42;
// assert(false) is never stripped from the code, it generates an
// error in debug builds, and it becomes a HALT instruction in
// -release mode.
//
// It's used as a mark by the D type system. If you remove this
// line the compiles gives an error:
//
// Error: function assertions.foo no return exp;
// or assert(0); at end of function
assert(false, "This can't happen.");
}
▲void main() pure {
int x = foo(true);
// A regular assertion, it throws an error.
// Use -release to disable it.
// It can be used in nothrow functions.
assert(x == 42, "x is not 42");
// This throws an exception and it can't be disabled.
// There are some different versions of this lazy function.
enforce(x == 42, "x is not 42");
}</lang>
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