C++ operator overloading q.

[suresh shenoy]

Hello,

I came across a snippet of code which I was not able to interpret
correctly.

typedef CategoryStream& (*cspf) (CategoryStream&);

CategoryStream& CategoryStream::operator<< (cspf pf) {
return (*pf)(*this);
}

If anyone could explain each line, it would be great!

[Hans Mull]

suresh shenoy schrieb:

Hello,

I came across a snippet of code which I was not able to interpret
correctly.

I think this is to be interpreted as follows (I'm not really sure about
the typedef):

>
typedef CategoryStream& (*cspf) (CategoryStream&);

That defines a Reference to CategoryStream as a dereference of cspf
(probably something defined by the library

>
CategoryStream& CategoryStream::operator<< (cspf pf) {
return (*pf)(*this);
}

This overloads an operator so the compiler can interpret the following code:
CategoryStream stream;
stream << pf; //pf is a cspf Instance; statement returns a
//CategoryStream&
//This is equivalent to writing (*pf)(*this)

>
If anyone could explain each line, it would be great!

I hope this is right. Kind reagrds, Hans

[James Kanze]

On Feb 8, 7:57 pm, suresh shenoy <[e-mail]:

I came across a snippet of code which I was not able to interpret
correctly.

typedef CategoryStream& (*cspf) (CategoryStream&);

Declares cspf as a pointer to a function which returns a
CategoryStream&, and has a single parameter of type
CategoryStream&.

CategoryStream& CategoryStream::operator<< (cspf pf) {
return (*pf)(*this);
}

First, this is the implementation of a member function; it will
be called in expressions like:

CategoryStream s ;
s << someFunction ;

If anyone could explain each line, it would be great!

It's the standard idiom for a manipulator not taking any
arguments in a stream. See, for example, things like std::hex,
std::uppercase, etc., and the way they work in std::ostream&.

--
James Kanze (GABI Software) email:ja*********@gmail.com
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