On Mon, Jul 11, 2016 at 4:40 PM, Erich Rickheit KSC
<rickh...@numachi.com> wrote:
> Ian Lance Taylor wrote:
>> On Sat, Jul 9, 2016 at 4:38 PM, Erich Rickheit KSC <rickh...@numachi.com>
>> wrote:
>> > I found myself writing code like this:
>> >
>> > s := make([]byte, len)
>> > for i := 0; i < len; i++ {
>> > // fill in s with stringy goodness
>> > }
>> > return string(s)
>> >
>> > Does this reuse the memory in s for the string, or does it allocate new
>> > memory and copy? Or does escape analysis swoop in and make that decision?
>>
>> This will normally allocate new memory for the string and copy over
>> the bytes. I believe that the compiler could optimize this case, but
>> as far as I know no Go compiler currently implements that
>> optimization.
>>
>> Ian
>
> So, the lesson is, try to use []byte or []rune when I need manipulate text.
>
> In those cases where I do need to build actual string objects, are there
> ways to get the compiler to not do extra copies? For example, if I write
>
> str1 := "foo" + str2 + "bar" + secretStringConstant
>
> Does it know to build one string, or does it build the intermediates?
The gc compiler will build a single string.
> How about:
>
> str1 := "foo"
> str1 += str2
> str1 += "bar"
> str1 += secretStringConstant
I'm not sure. This might change with SSA.
Ian
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