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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:

[legend]Collaboration diagram for sc::PrefixKeyVal:

[legend]List of all members.

Public Methods
	~PrefixKeyVal ()
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.
	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)
	PrefixKeyVal (const char *, const Ref< KeyVal > &)
	PrefixKeyVal (const char *, const Ref< KeyVal > &, int)
	PrefixKeyVal (const char *, const Ref< KeyVal > &, int, int)
	PrefixKeyVal (const char *, const Ref< KeyVal > &, int, int, int)
	PrefixKeyVal (const char *, const Ref< KeyVal > &, int, int, int, int)

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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: (
      f1 = 1.0
      a<A>: (
        f0 = 2.0
      )
    )
    

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The documentation for this class was generated from the following file:

• keyval.h

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