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clean up a TODO

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Rob Pike 2009-08-03 14:07:19 -07:00
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58
doc/effective_go.html
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@ -1,6 +1,14 @@
<h2 id="introduction">Introduction</h2> <h2 id="introduction">Introduction</h2>
<p>
Go is a new language. Although it's in the C family of languages
it has some unusual properties that make effective Go programs
different in character from programs in C, C++, or Java.
To write Go well, it's important to understand its properties
and idioms.
</p>
<p> <p>
This document gives tips for writing clear, idiomatic Go code This document gives tips for writing clear, idiomatic Go code
and points out common mistakes. and points out common mistakes.
@ -287,11 +295,11 @@ A comment can introduce a group of related constants or variables.
</p> </p>
<pre> <pre>
// Flags to Open wrapping those of the underlying system. // Flags to Open, wrapping those of the underlying system.
// Not all flags may be implemented on a given system. // Not all flags may be implemented on a given system.
const ( const (
O_RDONLY = syscall.O_RDONLY; // open the file read-only. O_RDONLY = syscall.O_RDONLY; // Open file read-only.
O_WRONLY = syscall.O_WRONLY; // open the file write-only. O_WRONLY = syscall.O_WRONLY; // Open file write-only.
... ...
) )
</pre> </pre>
@ -303,9 +311,9 @@ a mutex.
</p> </p>
<pre> <pre>
// Variables protected by counterLock. // Variables protected by countLock.
var ( var (
counterLock sync.Mutex; countLock sync.Mutex;
inputCount uint32; inputCount uint32;
outputCount uint32; outputCount uint32;
errorCount uint32; errorCount uint32;
@ -357,9 +365,8 @@ the buffered <code>Reader</code> is <code>bufio.Reader</code>, not <code>bufio.B
Similarly, <code>once.Do</code> is as precise and evocative as Similarly, <code>once.Do</code> is as precise and evocative as
<code>once.DoOrWaitUntilDone</code>, and <code>once.Do(f)</code> reads <code>once.DoOrWaitUntilDone</code>, and <code>once.Do(f)</code> reads
better than <code>once.DoOrWaitUntilDone(f)</code>. better than <code>once.DoOrWaitUntilDone(f)</code>.
Contrary to popular belief, encoding small essays into Encoding small essays into function names is not Go style;
function names does not make it possible clear names with good documentation is.
to use them without documentation.
</p> </p>
<h3 id="interfacers">Use the -er convention for interface names</h3> <h3 id="interfacers">Use the -er convention for interface names</h3>
@ -564,24 +571,41 @@ codeUsing(f);
<h3 id="error-context">Return structured errors</h3> <h3 id="error-context">Return structured errors</h3>
Implementations of <code>os.Error</code>s should Implementations of <code>os.Error</code> should
describe the error but also include context. describe the error and provide context.
For example, <code>os.Open</code> returns an <code>os.PathError</code>: For example, <code>os.Open</code> returns an <code>os.PathError</code>:
<a href="/src/pkg/os/file.go">/src/pkg/os/file.go</a>: <a href="/src/pkg/os/file.go">/src/pkg/os/file.go</a>:
<pre> <pre>
XXX definition of PathError and .String // PathError records an error and the operation and
// file path that caused it.
type PathError struct {
Op string;
Path string;
Error Error;
}
func (e *PathError) String() string {
return e.Op + " " + e.Path + ": " + e.Error.String();
}
</pre> </pre>
<code>PathError</code>'s <code>String</code> formats <code>PathError</code>'s <code>String</code> formats
the error nicely and is the usual way the error gets used. the error nicely, including the operation and file name
tha failed; just printing the error generates a
message, such as
<pre>
open /etc/passwx: no such file or directory
</pre>
that is useful even if printed far from the call that
triggered it.
</p>
<p>
Callers that care about the precise error details can Callers that care about the precise error details can
use a type switch or a type guard to look for specific use a type switch or a type guard to look for specific
errors and then extract details. errors and extract details.
</p>
<pre>
XXX example here - MkdirAll
</pre>
<h2 id="types">Programmer-defined types</h2> <h2 id="types">Programmer-defined types</h2>