mirror of
https://github.com/golang/go
synced 2024-11-21 11:14:40 -07:00
FAQ: update
R=bradfitz, r, dsymonds, edsrzf, rsc CC=golang-dev https://golang.org/cl/5345055
This commit is contained in:
parent
520f9dea13
commit
8649444002
@ -496,8 +496,8 @@ It's possible to use these ideas to construct something analogous to
|
||||
type-safe Unix pipes. For instance, see how <code>fmt.Fprintf</code>
|
||||
enables formatted printing to any output, not just a file, or how the
|
||||
<code>bufio</code> package can be completely separate from file I/O,
|
||||
or how the <code>crypto</code> packages stitch together block and
|
||||
stream ciphers. All these ideas stem from a single interface
|
||||
or how the <code>image</code> packages generate compressed
|
||||
image files. All these ideas stem from a single interface
|
||||
(<code>io.Writer</code>) representing a single method
|
||||
(<code>Write</code>). And that's only scratching the surface.
|
||||
</p>
|
||||
@ -681,7 +681,7 @@ examples and also have them be statically checked.
|
||||
Can I convert a []T to an []interface{}?</h3>
|
||||
|
||||
<p>
|
||||
Not directly because they do not have the same representation in memory.
|
||||
Not directly, because they do not have the same representation in memory.
|
||||
It is necessary to copy the elements individually to the destination
|
||||
slice. This example converts a slice of <code>int</code> to a slice of
|
||||
<code>interface{}</code>:
|
||||
@ -841,10 +841,13 @@ for more information about how to proceed.
|
||||
When are function parameters passed by value?</h3>
|
||||
|
||||
<p>
|
||||
Everything in Go is passed by value. A function always gets a copy of the
|
||||
As in all languages in the C family, everything in Go is passed by value.
|
||||
That is, a function always gets a copy of the
|
||||
thing being passed, as if there were an assignment statement assigning the
|
||||
value to the parameter. For instance, copying a pointer value makes a copy of
|
||||
the pointer, not the data it points to.
|
||||
value to the parameter. For instance, passing an <code>int</code> value
|
||||
to a function makes a copy of the <code>int</code>, and passing a pointer
|
||||
value makes a copy of the pointer, but not the data it points to.
|
||||
(See the next section for a discussion of how this affects method receivers.)
|
||||
</p>
|
||||
|
||||
<p>
|
||||
@ -946,6 +949,12 @@ floating-point numbers.
|
||||
The default size of a floating-point constant is <code>float64</code>.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
At the moment, all implementations use 32-bit ints, an essentially arbitrary decision.
|
||||
However, we expect that <code>int</code> will be increased to 64 bits on 64-bit
|
||||
architectures in a future release of Go.
|
||||
</p>
|
||||
|
||||
<h3 id="stack_or_heap">
|
||||
How do I know whether a variable is allocated on the heap or the stack?</h3>
|
||||
|
||||
@ -966,9 +975,10 @@ garbage-collected heap to avoid dangling pointer errors.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
In the current compilers, the analysis is crude: if a variable has its address
|
||||
taken, that variable is allocated on the heap. We are working to improve this
|
||||
analysis so that more data is kept on the stack.
|
||||
In the current compilers, if a variable has its address taken, that variable
|
||||
is a candidate for allocation on the heap. However, a basic <em>escape
|
||||
analysis</em> recognizes some cases when such variables will not
|
||||
live past the return from the function and can reside on the stack.
|
||||
</p>
|
||||
|
||||
<h2 id="Concurrency">Concurrency</h2>
|
||||
@ -1008,7 +1018,7 @@ effectively equal to the number of running goroutines.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
Programs that perform concurrent computation should benefit from an increase in
|
||||
Programs that perform parallel computation should benefit from an increase in
|
||||
<code>GOMAXPROCS</code>. (See the <a
|
||||
href="http://golang.org/pkg/runtime/#GOMAXPROCS"><code>runtime</code> package's
|
||||
documentation</a>.)
|
||||
@ -1227,16 +1237,16 @@ it now. <code>Gccgo</code>'s run-time support uses <code>glibc</code>.
|
||||
control; it is
|
||||
compiled with a version of the Plan 9 C compiler that supports
|
||||
segmented stacks for goroutines.
|
||||
Work is underway to provide the same stack management in
|
||||
<code>gccgo</code>.
|
||||
The <code>gccgo</code> compiler also implements segmented
|
||||
stacks, supported by recent modifications to its linker.
|
||||
</p>
|
||||
|
||||
<h3 id="Why_is_my_trivial_program_such_a_large_binary">
|
||||
Why is my trivial program such a large binary?</h3>
|
||||
|
||||
<p>
|
||||
The gc tool chain (<code>5l</code>, <code>6l</code>, and <code>8l</code>) only
|
||||
generate statically linked binaries. All Go binaries therefore include the Go
|
||||
The linkers in the gc tool chain (<code>5l</code>, <code>6l</code>, and <code>8l</code>)
|
||||
do static linking. All Go binaries therefore include the Go
|
||||
run-time, along with the run-time type information necessary to support dynamic
|
||||
type checks, reflection, and even panic-time stack traces.
|
||||
</p>
|
||||
@ -1316,7 +1326,7 @@ For instance, pidigits depends on a multi-precision math package, and the C
|
||||
versions, unlike Go's, use <a href="http://gmplib.org/">GMP</a> (which is
|
||||
written in optimized assembler).
|
||||
Benchmarks that depend on regular expressions (regex-dna, for instance) are
|
||||
essentially comparing Go's stopgap <a href="/pkg/regexp">regexp package</a> to
|
||||
essentially comparing Go's native <a href="/pkg/regexp">regexp package</a> to
|
||||
mature, highly optimized regular expression libraries like PCRE.
|
||||
</p>
|
||||
|
||||
@ -1373,7 +1383,7 @@ the declaration
|
||||
declares <code>a</code> to be a pointer but not <code>b</code>; in Go
|
||||
</p>
|
||||
<pre>
|
||||
var a, b *int;
|
||||
var a, b *int
|
||||
</pre>
|
||||
<p>
|
||||
declares both to be pointers. This is clearer and more regular.
|
||||
@ -1381,11 +1391,11 @@ Also, the <code>:=</code> short declaration form argues that a full variable
|
||||
declaration should present the same order as <code>:=</code> so
|
||||
</p>
|
||||
<pre>
|
||||
var a uint64 = 1;
|
||||
var a uint64 = 1
|
||||
</pre>
|
||||
has the same effect as
|
||||
<pre>
|
||||
a := uint64(1);
|
||||
a := uint64(1)
|
||||
</pre>
|
||||
<p>
|
||||
Parsing is also simplified by having a distinct grammar for types that
|
||||
|
Loading…
Reference in New Issue
Block a user