HP Integrity NonStop J-Series - Manual (Page 134)

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©Copyright 1996 Rogue Wave Software
Using Templates Without the Standard Library
Several of the Tools.h++ templates, such as RWTValVector , RWTPtrVector , RWTIsvSlist ,
and RWTIsvDlist , are not based on the Standard C++ Library. You can use them on any of our
certified platforms. Also, as mentioned previously in the Introduction, you can use many of the so-called
standard library-based templates without the Standard C++ Library, as long as you keep to a subset of the
full interface.
Keeping the Standard C++ Library in Mind for Portability
The restricted subset interfaces are almost fully upward compatible with their corresponding standard
library-based interfaces. The major difference you will find is that some collections take a different
number of template parameters, depending on which underlying implementation they are using. For
example, when
RWTPtrHashSet is used with the Standard C++ Library, it takes three template arguments
as described in Hash Functions and Equalitors above. However, when that same class is used without the
Standard C++ Library, the restricted interface calls for only one template parameter, namely the type of
item being contained. To help you write portable code that works with or without the Standard C++
Library, Tools.h++ provides two macros:
Use the first macro, RWDefHArgs(T), standing for Rogue Wave Default Hash Arguments, for the
hash-based template collections. For example, by declaring: 1.
RWTPtrHashSet hset; 2.
you declare a hash-based set that will have the same semantics whether or not the Standard C++
Library is present. Note that you should not use a comma between the element type and the macro.
Without the Standard C++ Library, the macro expands to nothing and it is as if you had declared: 3.
RWTPtrHashSet hset; 4.
However, as soon as the Standard C++ Library becomes available, the macro expands as follows: 5.
RWTPtrHashSet, equal_to > hset; 6.
This declaration satisfies the full requirement of the standard library-based interface for all three
parameters, and keeps the semantics consistent with the alternative non standard-library based
implementation. 7.
The second macro, RWDefCArgs(T), is similar to the first. Standing for Rogue Wave Default
Comparison Arguments, RWDefCArgs(T)is available for use with
RWTPtrSortedVector and
RWTValSortedVector . For example:
8.
RWTValSortedVector srtvec; 9.