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  1. 21 Apr, 2011 13 commits
  3. 20 Apr, 2011 13 commits
  5. 19 Apr, 2011 9 commits
  7. 18 Apr, 2011 5 commits
    • Russ Cox's avatar
      5c: make alignment rules match 5g, just like 6c matches 6g · b331f3cf
      Russ Cox authored 
      I should have done this a year ago in:

        changeset:   5137:686b18098944
        user:        Russ Cox <rsc@golang.org>
        date:        Thu Mar 25 14:05:54 2010 -0700
        files:       src/cmd/8c/swt.c
        description:
        make alignment rules match 8g, just like 6c matches 6g.

        R=ken2
        CC=golang-dev
        https://golang.org/cl/760042

R=ken2
CC=golang-dev
https://golang.org/cl/4437054
      b331f3cf
    • Russ Cox's avatar
      http: fix IP confusion in TestServerTimeouts · 857f17d3
      Russ Cox authored 
      Don't assume that localhost == 127.0.0.1.
It might be ::1.

R=bradfitzgo
CC=golang-dev
https://golang.org/cl/4430055
      857f17d3
    • Russ Cox's avatar
      changes for more restricted reflect.SetValue · cded21a3
      Russ Cox authored 
      R=golang-dev, r
CC=golang-dev
https://golang.org/cl/4423043
      cded21a3
    • Russ Cox's avatar
      reflect: more efficient; cannot Set result of NewValue anymore · 40fccbce
      Russ Cox authored 
       * Reduces malloc counts during gob encoder/decoder test from 6/6 to 3/5.

The current reflect uses Set to mean two subtly different things.

(1) If you have a reflect.Value v, it might just represent
itself (as in v = reflect.NewValue(42)), in which case calling
v.Set only changed v, not any other data in the program.

(2) If you have a reflect Value v derived from a pointer
or a slice (as in x := []int{42}; v = reflect.NewValue(x).Index(0)),
v represents the value held there.  Changing x[0] affects the
value returned by v.Int(), and calling v.Set affects x[0].

This was not really by design; it just happened that way.

The motivation for the new reflect implementation was
to remove mallocs.  The use case (1) has an implicit malloc
inside it.  If you can do:

       v := reflect.NewValue(0)
       v.Set(42)
       i := v.Int()  // i = 42

then that implies that v is referring to some underlying
chunk of memory in order to remember the 42; that is,
NewValue must have allocated some memory.

Almost all the time you are using reflect the goal is to
inspect or to change other data, not to manipulate data
stored solely inside a reflect.Value.

This CL removes use case (1), so that an assignable
reflect.Value must always refer to some other piece of data
in the program.  Put another way, removing this case would
make

       v := reflect.NewValue(0)
       v.Set(42)

as illegal as

       0 = 42.

It would also make this illegal:

       x := 0
       v := reflect.NewValue(x)
       v.Set(42)

for the same reason.  (Note that right now, v.Set(42) "succeeds"
but does not change the value of x.)

If you really wanted to make v refer to x, you'd start with &x
and dereference it:

       x := 0
       v := reflect.NewValue(&x).Elem()  // v = *&x
       v.Set(42)

It's pretty rare, except in tests, to want to use NewValue and then
call Set to change the Value itself instead of some other piece of
data in the program.  I haven't seen it happen once yet while
making the tree build with this change.

For the same reasons, reflect.Zero (formerly reflect.MakeZero)
would also return an unassignable, unaddressable value.
This invalidates the (awkward) idiom:

       pv := ... some Ptr Value we have ...
       v := reflect.Zero(pv.Type().Elem())
       pv.PointTo(v)

which, when the API changed, turned into:

       pv := ... some Ptr Value we have ...
       v := reflect.Zero(pv.Type().Elem())
       pv.Set(v.Addr())

In both, it is far from clear what the code is trying to do.  Now that
it is possible, this CL adds reflect.New(Type) Value that does the
obvious thing (same as Go's new), so this code would be replaced by:

       pv := ... some Ptr Value we have ...
       pv.Set(reflect.New(pv.Type().Elem()))

The changes just described can be confusing to think about,
but I believe it is because the old API was confusing - it was
conflating two different kinds of Values - and that the new API
by itself is pretty simple: you can only Set (or call Addr on)
a Value if it actually addresses some real piece of data; that is,
only if it is the result of dereferencing a Ptr or indexing a Slice.

If you really want the old behavior, you'd get it by translating:

       v := reflect.NewValue(x)

into

       v := reflect.New(reflect.Typeof(x)).Elem()
       v.Set(reflect.NewValue(x))

Gofix will not be able to help with this, because whether
and how to change the code depends on whether the original
code meant use (1) or use (2), so the developer has to read
and think about the code.

You can see the effect on packages in the tree in
https://golang.org/cl/4423043/.

R=r
CC=golang-dev
https://golang.org/cl/4435042
      40fccbce
    • Brad Fitzpatrick's avatar
      mime: add a TODO, fix the format of an error · 6211b596
      Brad Fitzpatrick authored 
      R=r, rsc1
CC=golang-dev
https://golang.org/cl/4440054
      6211b596