TRAP

TRAP (_r, _s) {                                                     \
    TInt& __rref = _r;                                      \
    __rref = 0;                                             \
    { TRAP_INSTRUMENTATION_START; }                         \
    try {                                                  \
        __WIN32SEHTRAP                                      \
        TTrapHandler* ____t = User::MarkCleanupStack();     \
        _s;                                                 \
        User::UnMarkCleanupStack(____t);                    \
        { TRAP_INSTRUMENTATION_NOLEAVE; }                   \
        __WIN32SEHUNTRAP                                    \
        }                                                   \
    catch (XLeaveException& l)                              \
        {                                                   \
        __rref = l.GetReason();                             \
        { TRAP_INSTRUMENTATION_LEAVE(__rref); }             \
        }                                                   \
    catch (...)                                             \
        {                                                   \
        User::Invariant();                                  \
        }                                                   \
    { TRAP_INSTRUMENTATION_END; }                           \
    }

Description

Executes the set of C++ statements _s under a trap harness.

Use this macro as a C++ statement.

_r must be a TInt which has already been declared; if any of the C++ statements _s leaves, then the leave code is returned in _r, otherwise _r is set to KErrNone.

_s can consist of multiple C++ statements; in theory, _s can consist of any legal C++ code but in practice, such statements consist of simple function calls, e.g. Foo() or an assignment of some value to the result of a function call, e.g. functionValue=GetFoo().

A cleanup stack is constructed for the set of C++ statements _s. If any function in _s leaves, objects pushed to the cleanup stack are cleaned-up. In addition, if any of the C++ statements in _s leaves, then remaining C++ code in _s is not executed and any variables which are assigned within that remaining code are not defined.

Parameters

_r An lvalue, convertible to TInt&, which will receive the result of any User::Leave() executed within _s or, if no leave occurred, it will be set to KErrNone. The value of _r on entry is not used. _s C++ statements which will be executed under a trap harness.