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clarifying ambiguity of evaluation order

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DELTA=16  (0 added, 3 deleted, 13 changed)
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Robert Griesemer 2009-05-01 17:00:16 -07:00
parent eac5db7f4c
commit 4f18549c02
1 changed files with 9 additions and 12 deletions
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doc/go_spec.html
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@ -2905,21 +2905,18 @@ order. Otherwise, the order of evaluation is unspecified.
</p>
<p>
For example, while evaluating the arguments for this call
to function <code>f</code>,
For example, in the assignment
</p>
<pre>
f(g(), h() + x[i()], <-c)
y[f()], ok = g(h(), i() + x[j()], <-c), k()
</pre>
<p>
the call to <code>g()</code> happens before the call to <code>h()</code>,
which happens before the call to <code>i()</code>, all of
of which happen before receiving the value from the channel
<code>c</code>.
However, the order of those events compared to the evaluation of
<code>f</code>, the evaluation of <code>x</code>, and the indexing
of <code>x</code> by the return value of
<code>i()</code> is not specified.
the function calls and communication happen in the order
<code>f()</code>, <code>h()</code>, <code>i()</code>, <code>j()</code>,
<code><-c</code>, <code>g()</code>, and <code>k()</code>.
However, the order of those events compared to the evaluation
and indexing of <code>x</code> and the evaluation
of <code>y</code> is not specified.
</p>
<hr/>
@ -3164,7 +3161,7 @@ type of a specially annotated switch expression.
In an expression switch,
the switch expression is evaluated and
the case expressions, which need not be constants,
are evaluated top-to-bottom; the first one that equals the
are evaluated left-to-right and top-to-bottom; the first one that equals the
switch expression
triggers execution of the statements of the associated case;
the other cases are skipped.