Go Package io: Difference between revisions
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The <tt>io</tt> package consists of a few functions, but mostly interfaces used by other packages. | The <tt>io</tt> package consists of a few functions, but mostly interfaces used by other packages. | ||
=<tt>io.EOF</tt>= | |||
The error returned by I/O operations that encounter the end of file. It can be tested with: | |||
<syntaxhighlight lang='go'> | |||
_, err := ... | |||
if errors.Is(err, io.EOF) { | |||
// is EOF | |||
... | |||
} | |||
</syntaxhighlight> | |||
=<tt>Reader</tt>= | =<tt>Reader</tt>= | ||
| Line 18: | Line 30: | ||
<code>Reader</code>s can be used to unmarshall JSON into structs as shown here: {{Internal|JSON_in_Go#With_a_Reader|Unmarshalling JSON from a Reader into a struct}} | <code>Reader</code>s can be used to unmarshall JSON into structs as shown here: {{Internal|JSON_in_Go#With_a_Reader|Unmarshalling JSON from a Reader into a struct}} | ||
Files opened with <code>[[Go_Package_os#os.Create.28.29|os.Create()]]</code> implement <code>io.Reader</code>. | |||
==<span id='WBSR'></span>Wrapping a <tt>[]byte</tt> into a <tt>Reader</tt>== | |||
A <code>[]byte</code> can be wrapped into a <code>Reader</code> with: | |||
<syntaxhighlight lang='go'> | |||
import "bytes" | |||
bs := []byte("something") | |||
r := bytes.NewReader(bs) | |||
</syntaxhighlight> | |||
==Getting a <tt>Reader</tt> from a <tt>string</tt>== | |||
<syntaxhighlight lang='go'> | |||
s := "some string" | |||
reader := strings.NewReader(s) | |||
</syntaxhighlight> | |||
=<tt>Writer</tt>= | =<tt>Writer</tt>= | ||
{{External|https://golang.org/pkg/io/#Writer}} | {{External|https://golang.org/pkg/io/#Writer}} | ||
Files opened with <code>[[Go_Package_os#os.Create.28.29|os.Create()]]</code> implement <code>io.Writer</code>. | |||
=<tt>Closer</tt>= | =<tt>Closer</tt>= | ||
{{External|https://golang.org/pkg/io/#Closer}} | {{External|https://golang.org/pkg/io/#Closer}} | ||
Files opened with <code>[[Go_Package_os#os.Create.28.29|os.Create()]]</code> implement <code>io.Closer</code>. | |||
=<tt>ReadCloser</tt>= | =<tt>ReadCloser</tt>= | ||
An interface that exposes basic <code>Read()</code> and <code>Close()</code> methods. The <code>http.Request</code> body is a <code>ReadCloser</code>. See <code>[[#Reader|Reader]]</code>. | An interface that exposes basic <code>Read()</code> and <code>Close()</code> methods. The <code>http.Request</code> body is a <code>ReadCloser</code>. See <code>[[#Reader|Reader]]</code>. | ||
Latest revision as of 21:17, 29 February 2024
External
Internal
Overview
The io package consists of a few functions, but mostly interfaces used by other packages.
io.EOF
The error returned by I/O operations that encounter the end of file. It can be tested with:
_, err := ...
if errors.Is(err, io.EOF) {
// is EOF
...
}
Reader
An interface that exposes Read().
Readers can be used to unmarshall JSON into structs as shown here:
Files opened with os.Create() implement io.Reader.
Wrapping a []byte into a Reader
A []byte can be wrapped into a Reader with:
import "bytes"
bs := []byte("something")
r := bytes.NewReader(bs)
Getting a Reader from a string
s := "some string"
reader := strings.NewReader(s)
Writer
Files opened with os.Create() implement io.Writer.
Closer
Files opened with os.Create() implement io.Closer.
ReadCloser
An interface that exposes basic Read() and Close() methods. The http.Request body is a ReadCloser. See Reader.