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.Apple-tab-span
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}
26 <p class=
"p1"><span class=
"s1"><b>Pkey
<span class=
"Apple-tab-span"> </span><span class=
"Apple-tab-span"> </span><span class=
"Apple-tab-span"> </span></b></span><b>access a key in an event stream
</b></p>
27 <p class=
"p2"><b></b><br></p>
28 <p class=
"p1">superclass:
<a href=
"Pattern.html"><span class=
"s2">Pattern
</span></a></p>
29 <p class=
"p3"><br></p>
30 <p class=
"p1">Pkey simplifies backward access to values in an event being processed by
<a href=
"Pbind.html"><span class=
"s2">Pbind
</span></a> or another event pattern.
</p>
31 <p class=
"p3"><br></p>
32 <p class=
"p1"><b>*new(key)
</b></p>
33 <p class=
"p3"><br></p>
34 <p class=
"p1">The
<b>key
</b> is the name of the event variable to read from.
</p>
35 <p class=
"p3"><br></p>
36 <p class=
"p3"><br></p>
37 <p class=
"p4">// \b should thus take twice the value of \a in each event:
</p>
38 <p class=
"p5">p =
<span class=
"s3">Pbind
</span>(
<span class=
"s4">\a
</span>,
<span class=
"s3">Pwhite
</span>(
1,
10,
<span class=
"s3">inf
</span>),
<span class=
"s4">\b
</span>,
<span class=
"s3">Pkey
</span>(
<span class=
"s4">\a
</span>) *
2).asStream;
</p>
39 <p class=
"p3"><br></p>
40 <p class=
"p3"><br></p>
41 <p class=
"p6"><span class=
"s5">p.next(())
<span class=
"Apple-tab-span"> </span></span>// for Pbind, must pass in a default event even if empty
</p>
42 <p class=
"p7"><br></p>
43 <p class=
"p5">(
<span class=
"s4">'a'
</span>:
10,
<span class=
"s4">'b'
</span>:
20 )
</p>
44 <p class=
"p5">(
<span class=
"s4">'a'
</span>:
2,
<span class=
"s4">'b'
</span>:
4 )
</p>
45 <p class=
"p5">(
<span class=
"s4">'a'
</span>:
5,
<span class=
"s4">'b'
</span>:
10 )
</p>
46 <p class=
"p5">(
<span class=
"s4">'a'
</span>:
4,
<span class=
"s4">'b'
</span>:
8 )
</p>
47 <p class=
"p5">(
<span class=
"s4">'a'
</span>:
2,
<span class=
"s4">'b'
</span>:
4 )
</p>
