add simple text about & and *.
clean up html: PLEASE RUN TIDY WHEN YOU EDIT THIS DOCUMENT
deferring method value update until we decide what happens.
R=gri
DELTA=50 (38 added, 4 deleted, 8 changed)
OCL=26609
CL=26612
diff --git a/doc/go_spec.html b/doc/go_spec.html
index 4100610..383cae1 100644
--- a/doc/go_spec.html
+++ b/doc/go_spec.html
@@ -22,7 +22,6 @@
[ ] need to talk about precise int/floats clearly
[ ] iant suggests to use abstract/precise int for len(), cap() - good idea
(issue: what happens in len() + const - what is the type?)
-[ ] cleanup convert() vs T() vs x.(T) - convert() should go away?
[ ] fix "else" part of if statement
[ ] cleanup: 6g allows: interface { f F } where F is a function type.
fine, but then we should also allow: func f F {}, where F is a function type.
@@ -124,6 +123,7 @@
and if so, does a label followed by an empty statement (a semicolon) still denote
a for loop that is following, and can break L be used inside it?
[x] there is some funniness regarding ';' and empty statements and label decls
+[x] cleanup convert() vs T() vs x.(T) - convert() should go away?
-->
@@ -1403,7 +1403,6 @@
Functions:
cap len make new panic panicln print println
- (TODO: typeof??)
Packages:
sys (TODO: does sys endure?)
@@ -2664,17 +2663,30 @@
<h3>Address operators</h3>
-<!--TODO(r): This section is a mess. Skipping it for now.-->
-
<p>
-<font color=red>TODO: Need to talk about unary "*", clean up section below.</font>
+The unary prefix address-of operator <code>&</code> generates the address of its operand, which must be a variable,
+pointer indirection, field selector, or array or slice indexing operation. It is illegal to take the address of a function
+result variable.
+Given an operand of pointer type, the unary prefix pointer indirection operator <code>*</code> retrieves the value pointed
+to by the operand.
+</p>
+
+<pre>
+&x
+&a[f(2)]
+*p
+*pf(x)
+</pre>
+
<p>
<font color=red>TODO: This text needs to be cleaned up and go elsewhere, there are no address
operators involved.
</font>
+</p>
<p>
-Methods are a form of function, and a method ``value'' has a function type.
+Methods are a form of function and a method ``value'' has a function type.
Consider the type T with method M:
+</p>
<pre>
type T struct {
@@ -2684,25 +2696,33 @@
var t *T;
</pre>
+<p>
To construct the value of method M, one writes
+</p>
<pre>
t.M
</pre>
+<p>
using the variable t (not the type T).
<font color=red>TODO: It makes perfect sense to be able to say T.M (in fact, it makes more
sense then t.M, since only the type T is needed to find the method M, i.e.,
its address). TBD.
</font>
+</p>
+<p>
The expression t.M is a function value with type
+</p>
<pre>
func (t *T, a int) int
</pre>
+<p>
and may be invoked only as a function, not as a method:
+</p>
<pre>
var f func (t *T, a int) int;
@@ -2710,30 +2730,39 @@
x := f(t, 7);
</pre>
+<p>
Note that one does not write t.f(7); taking the value of a method demotes
it to a function.
+</p>
+<p>
In general, given type T with method M and variable t of type T,
the method invocation
+</p>
<pre>
t.M(args)
</pre>
+<p>
is equivalent to the function call
+</p>
<pre>
(t.M)(t, args)
</pre>
+<p>
<font color=red>
TODO: should probably describe the effect of (t.m) under §Expressions if t.m
denotes a method: Effect is as described above, converts into function.
</font>
+</p>
<p>
If T is an interface type, the expression t.M does not determine which
underlying type's M is called until the point of the call itself. Thus given
T1 and T2, both implementing interface I with method M, the sequence
+</p>
<pre>
var t1 *T1;
@@ -2743,8 +2772,10 @@
m(t2, 7);
</pre>
+<p>
will invoke t2.M() even though m was constructed with an expression involving
t1. Effectively, the value of m is a function literal
+</p>
<pre>
func (recv I, a int) {
@@ -2752,13 +2783,16 @@
}
</pre>
+<p>
that is automatically created.
+</p>
<p>
<font color=red>
TODO: Document implementation restriction: It is illegal to take the address
of a result parameter (e.g.: func f() (x int, p *int) { return 2, &x }).
(TBD: is it an implementation restriction or fact?)
</font>
+</p>
<h3>Communication operators</h3>
@@ -3131,11 +3165,13 @@
An expression or type specifier is compared to the "cases"
inside the "switch" to determine which branch
to execute.
+</p>
<pre class="grammar">
SwitchStat = ExprSwitchStat | TypeSwitchStat .
</pre>
+<p>
There are two forms: expression switches and type switches.
In an expression switch, the cases contain expressions that are compared
against the value of the switch expression.
@@ -3690,7 +3726,6 @@
<h2>Predeclared functions</h2>
<ul>
<li>cap
- <li>convert
<li>len
<li>make
<li>new
@@ -3698,7 +3733,6 @@
<li>panicln
<li>print
<li>println
- <li>typeof
</ul>
<h3>Length and capacity</h3>
