Experimental Physics and
Industrial Control System

Begin forwarded message:

From: Kay-Uwe Kasemir <[email protected]>
Date: September 26, 2005 10:58:02 EDT
To: Jeff Hill <[email protected]>
Subject: Re: data access structures, strings



On Sep 23, 2005, at 18:43 , Jeff Hill wrote:

its easy enough to write a
convenience library that implements "destination->r =

data_catalog->find("color")->find("red")->toDouble()" on top of the data

access minimalist interfaces.

Here's my example of what
the "pulling"

   data_catalog->find("color")->find("red")->toInt()
   data_catalog->find("color")->find("green")->toInt()
   data_catalog->find("color")->find("blue")->toInt()

turns into based on the dataAccess callback mechanism:

class PickRGBPieces : public propertyViewer
{
public:
    PickRGBPieces()
    { in_color = have_r = have_g = have_b = false; }
    bool isValid()
    { return !in_color && have_r && have_g && have_b; }
    int getR()
    { return r; }
    int getG()
    { return g; }
    int getB()
    { return b; }

void reveal ( const propertyId &, const double &v, const propertyCatalog &x)

    {}

void reveal ( const propertyId &id, const int &v, const propertyCatalog &x)

    {
        if (in_color)
        {
            if (id == red_id)
            {
                r = v;
                have_r = true;
            }
            else if (id == green_id)
            {
                g = v;
                have_g = true;
            }
            else if (id == blue_id)
            {
                b = v;
                have_b = true;
            }
        }
    }

void reveal ( const propertyId &, const unsigned int &v, const propertyCatalog &x)

    {}

void reveal ( const propertyId &, const long &v, const propertyCatalog &x)

    {}

void reveal ( const propertyId &, const unsigned long &v, const propertyCatalog &x)

    {}

void reveal ( const propertyId &, const epicsTime &, const propertyCatalog &x)

    {}

void reveal ( const propertyId &, const stringSegment &, const propertyCatalog &x)

    {}
    void reveal ( const propertyId &, const enumStateSet & )
    {}

void reveal ( const propertyId &, const arraySegment &, const propertyCatalog &x)

    {}
    void reveal ( const propertyId &id, const propertyCatalog &x)
    {
        if (id == color_id)
        {
            in_color = true;
            x.traverse(*this);
            in_color = false;
        }
    }
private:
    bool in_color, have_r, have_g, have_b;
    int r, g, b;
};

PickRGBPieces rgb;
data_catalog.traverse(rgb);
if (rgb.isValid())
{
    cout << "Red   : " << rgb.getR() << "\n";
    cout << "Green : " << rgb.getG() << "\n";
    cout << "Blue  : " << rgb.getB() << "\n";
}


-Kay

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