sc::PrefixKeyVal Class Reference

PrefixKeyVal is a KeyVal that searches a different KeyVal using modified keys. More...

#include <keyval.h>

Inheritance diagram for sc::PrefixKeyVal:

sc::KeyVal sc::RefCount sc::Identity List of all members.

Public Member Functions

void errortrace (std::ostream &fp=ExEnv::err0())
 Write a message to fp describing the error.
void dump (std::ostream &fp=ExEnv::err0())
 Write a message to fp describing the error.
Constructors.
Construct a PrefixKeyVal, using the given prefix and indices.

 PrefixKeyVal (const Ref< KeyVal > &, int i)
 PrefixKeyVal (const Ref< KeyVal > &, int i, int j)
 PrefixKeyVal (const Ref< KeyVal > &, int i, int j, int k)
 PrefixKeyVal (const Ref< KeyVal > &, int i, int j, int k, int l)
 PrefixKeyVal (const Ref< KeyVal > &, const char *prefix)
 PrefixKeyVal (const Ref< KeyVal > &, const char *prefix, int i)
 PrefixKeyVal (const Ref< KeyVal > &, const char *prefix, int i, int j)
 PrefixKeyVal (const Ref< KeyVal > &, const char *prefix, int i, int j, int k)
 PrefixKeyVal (const Ref< KeyVal > &, const char *prefix, int i, int j, int k, int l)

Detailed Description

PrefixKeyVal is a KeyVal that searches a different KeyVal using modified keys.

This is convenient for reading keys grouped together with a common prefix. Consider the following code:

    sc::Ref<sc::KeyVal> keyval = new sc::PrefixKeyVal("A",original_keyval);
    int r = keyval->intvalue("x");
    
This code will assign to r the value associated with "x" in keyval. keyval will search for "x" by searching for "A::x" in original_keyval.

This class is important for implementing constructors that take KeyVal arguments. When an object is being constructed from a KeyVal, it may contain another object that must be constructed from a KeyVal. In order to let the sub-object read the correct keywords from the KeyVal, without knowledge of the containing objects keyword prefix, a PrefixKeyVal can be constructed. For example, the code

    class A: public DescribedClass {
       double f0_;
      public:
       A(const Ref<KeyVal> &keyval): f0_(keyval->doublevalue("f0")) {}
    }
    class B: public DescribedClass {
       double f1_;
       Ref<A> a_;
      public:
       B(const Ref<KeyVal> &keyval):
         f1_(keyval->doublevalue("f1")),
         a_(new PrefixKeyVal(keyval,"a"))
       {}
    };
can be used to read ParsedKeyVal input that looks like
    b<B>: (
      f1 = 1.0
      a<A>: (
        f0 = 2.0
      )
    )
    


The documentation for this class was generated from the following file:
Generated at Mon Dec 3 23:24:01 2007 for MPQC 2.3.1 using the documentation package Doxygen 1.5.2.