setprop

setprop -- sets a property value for a symbol.

Syntax

setprop (symbol, property, value)

		

Arguments

symbol

The symbol whose property will be set.

property

A symbol which identifies the property to be set.

value

The new value of the property.

Returns

The previous value for that property, or nil if there was no previous value.

Description

All symbols in Gamma may have properties assigned to them. These properties are not limited by the scope of the symbol, so that a symbol's property list is always global. A property consists of a (name . value) pair. Property lists are automatically maintained by setprop to ensure that each property name is unique for a symbol. A symbol may have any number of properties. A property for a symbol is queried using getprop.

The symbol and property are normally protected from evaluation when setting properties, using the # operator.

Example

    Gamma> setprop(#weight,#hilimit,1000);
    nil
    Gamma> setprop(#weight,#hiwarning,950);
    nil
    Gamma> setprop(#weight,#lowlimit,500);
    nil
    Gamma> setprop(#weight,#lowwarning,550);
    nil
    Gamma> getprop(#weight,#hilimit);
    1000
    Gamma> getprop(#weight,#lowwarning);
    550
    Gamma> 
    		

See the Trend Functions section of the Photon Functions chapter (Tutorial One) in the Cogent Tools Demo and Tutorials book for an example of this function used in context.

See Also

getprop, properties, setprops

Copyright 1995-2002 by Cogent Real-Time Systems, Inc.