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<H2><A NAME="sec:7.2"><SPAN class="sec-nr">7.2</SPAN> <SPAN class="sec-title">Accessing
instance variables (slots)</SPAN></A></H2>
<A NAME="sec:slots"></A>
<P>The method <A NAME="idx:objectbothslot:203"></A>`<B>object<CODE><-></CODE>slot</B>'
is used to access slots directly, bypassing possible methods with the
same name. Normally, it should only be used in
<B><CODE>-></CODE>initialise</B> (see below) and when defining a
method with the same name as a variable. Below is a fragment where a <TT>type</TT>
slot is displayed by a text object named <TT>type</TT> in a graphical
object. This variable has access <TT>get</TT>, associating a universal
method <B><CODE><-</CODE>type</B> that yields the current value of
the slot. The implementation of <B><CODE>-></CODE>type</B> uses the
<B><CODE>-></CODE>slot</B> method to write the argument in the <B><CODE><-</CODE>type</B>
slot and subsequently performs the required side-effects. The ...
indicate where the fragment is incomplete.
<PRE class="code">
variable(type, name, get, "Epistemological type").
initialise(D, Type:name, ...) :->
send_super(D, initialise),
send(D, slot, type, Type),
send(D, display, new(T, text(Type))),
send(T, name, type),
...
type(D, Type:type) :->
"Modify the epistemological type"::
send(D, slot, type, Type),
get(D, member, type, Text),
send(Text, string, Type).
</PRE>
<DL>
<DT><STRONG>object ->slot:</STRONG> <VAR>name, unchecked</VAR></DT>
<DD class="defbody">
</DD>
<DT><STRONG>object <-slot:</STRONG> <VAR>name</VAR></DT>
<DD class="defbody">
uncheckedRead or write slot without side-effects. The value will be
converted to the type of the instance variable addressed. An error is
raised if this conversion is not defined or if the slot does not exist.
</DD>
</DL>
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