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Re: [Q] What does "*isa" stand for ?
acs@aracnet.com writes:
> In a structured stream class,
> what does the structure member "*isa" stand for ?
>
> as in:
> struct _HTStructured {
> CONST HTStructuredClass * isa;
> ....
> }
>
The isa element is the _only_ required part of a stream interface that
a stream has to provide. It is of type HTStreamClass which is defined in
HTStream.html. The isa element is an attempt to hide the fact that you
can't subclass as in C++, for example.
If no take a look at any of the stream implementations - or any function
using a stream - it use the methods pointed by the isa element.
It is a question whether the extra indirection going through the isa element
causes performance problems but the tests that I have performed using alpha's
profiler doesn't give this impression.
Henrik
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