.TH "sc::PrefixKeyVal" 3 "Sun Oct 4 2020" "Version 2.3.1" "MPQC" \" -*- nroff -*-
.ad l
.nh
.SH NAME
sc::PrefixKeyVal \- \fBPrefixKeyVal\fP is a \fBKeyVal\fP that searches a different \fBKeyVal\fP using modified keys\&.  

.SH SYNOPSIS
.br
.PP
.PP
\fC#include <keyval\&.h>\fP
.PP
Inherits \fBsc::KeyVal\fP\&.
.SS "Public Member Functions"

.PP
.RI "\fBConstructors\&.\fP"
.br
Construct a \fBPrefixKeyVal\fP, using the given prefix and indices\&. 
.PP
.in +1c
.in +1c
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.RI "\fBPrefixKeyVal\fP (const \fBRef\fP< \fBKeyVal\fP > &, int i)"
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.RI "\fBPrefixKeyVal\fP (const \fBRef\fP< \fBKeyVal\fP > &, int i, int j)"
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.RI "\fBPrefixKeyVal\fP (const \fBRef\fP< \fBKeyVal\fP > &, int i, int j, int k)"
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.RI "\fBPrefixKeyVal\fP (const \fBRef\fP< \fBKeyVal\fP > &, int i, int j, int k, int l)"
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.RI "\fBPrefixKeyVal\fP (const \fBRef\fP< \fBKeyVal\fP > &, const char *prefix)"
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.RI "\fBPrefixKeyVal\fP (const \fBRef\fP< \fBKeyVal\fP > &, const char *prefix, int i)"
.br
.ti -1c
.RI "\fBPrefixKeyVal\fP (const \fBRef\fP< \fBKeyVal\fP > &, const char *prefix, int i, int j)"
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.ti -1c
.RI "\fBPrefixKeyVal\fP (const \fBRef\fP< \fBKeyVal\fP > &, const char *prefix, int i, int j, int k)"
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.ti -1c
.RI "\fBPrefixKeyVal\fP (const \fBRef\fP< \fBKeyVal\fP > &, const char *prefix, int i, int j, int k, int l)"
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.RI "\fB~PrefixKeyVal\fP ()"
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.RI "void \fBerrortrace\fP (std::ostream &fp=\fBExEnv::err0\fP())"
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.RI "Write a message to fp describing the error\&. "
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.RI "void \fBdump\fP (std::ostream &fp=\fBExEnv::err0\fP())"
.br
.RI "Write a message to fp describing the error\&. "
.in -1c
.in -1c
.SS "Additional Inherited Members"
.SH "Detailed Description"
.PP 
\fBPrefixKeyVal\fP is a \fBKeyVal\fP that searches a different \fBKeyVal\fP using modified keys\&. 

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

sc::Ref<sc::KeyVal> keyval = new \fBsc::PrefixKeyVal\fP('A',original_keyval);
int r = keyval->intvalue('x');
.fi
.PP
 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\&.
.PP
This class is important for implementing constructors that take \fBKeyVal\fP arguments\&. When an object is being constructed from a \fBKeyVal\fP, it may contain another object that must be constructed from a \fBKeyVal\fP\&. In order to let the sub-object read the correct keywords from the \fBKeyVal\fP, without knowledge of the containing objects keyword prefix, a \fBPrefixKeyVal\fP can be constructed\&. For example, the code 
.PP
.nf
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"))
   {}
};

.fi
.PP
 can be used to read \fBParsedKeyVal\fP input that looks like 
.PP
.nf

b<B>: (
  f1 = 1\&.0
  a<A>: (
    f0 = 2\&.0
  )
)
.fi
.PP
 

.SH "Author"
.PP 
Generated automatically by Doxygen for MPQC from the source code\&.