diff options
Diffstat (limited to 'content/errors-are-values.article')
| -rw-r--r-- | content/errors-are-values.article | 27 |
1 files changed, 14 insertions, 13 deletions
diff --git a/content/errors-are-values.article b/content/errors-are-values.article index 0876d7a..2d78aa7 100644 --- a/content/errors-are-values.article +++ b/content/errors-are-values.article @@ -1,9 +1,10 @@ -Errors are values +# Errors are values 12 Jan 2015 +Summary: A common point of discussion among Go programmers, especially those new to the language, is how to handle errors. The conversation often turns into a lament at the number of times the sequence Rob Pike -* Introduction +## A common point of discussion among Go programmers, especially those new to the language, is how to handle errors. @@ -33,7 +34,7 @@ Over time the Go code collects many such snippets, and the result feels clumsy. Regardless of whether this explanation fits, it is clear that these Go programmers miss a fundamental point about errors: -_Errors_are_values._ +_Errors are values._ Values can be programmed, and since errors are values, errors can be programmed. @@ -43,8 +44,8 @@ and application of some of those other things can make your program better, eliminating much of the boilerplate that arises if every error is checked with a rote if statement. Here's a simple example from the `bufio` package's -[[https://golang.org/pkg/bufio/#Scanner][`Scanner`]] type. -Its [[https://golang.org/pkg/bufio/#Scanner.Scan][`Scan`]] method performs the underlying I/O, +[`Scanner`](https://golang.org/pkg/bufio/#Scanner) type. +Its [`Scan`](https://golang.org/pkg/bufio/#Scanner.Scan) method performs the underlying I/O, which can of course lead to an error. Yet the `Scan` method does not expose an error at all. Instead, it returns a boolean, and a separate method, to be run at the end of the scan, @@ -86,7 +87,7 @@ Error handling does not obscure the flow of control. Under the covers what's happening, of course, is that as soon as `Scan` encounters an I/O error, it records it and returns `false`. -A separate method, [[https://golang.org/pkg/bufio/#Scanner.Err][`Err`]], +A separate method, [`Err`](https://golang.org/pkg/bufio/#Scanner.Err), reports the error value when the client asks. Trivial though this is, it's not the same as putting @@ -102,7 +103,7 @@ The discussion here is not about how to avoid checking errors, it's about using the language to handle errors with grace. The topic of repetitive error-checking code arose when I attended the autumn 2014 GoCon in Tokyo. -An enthusiastic gopher, who goes by [[https://twitter.com/jxck_][`@jxck_`]] on Twitter, +An enthusiastic gopher, who goes by [`@jxck_`](https://twitter.com/jxck_) on Twitter, echoed the familiar lament about error checking. He had some code that looked schematically like this: @@ -198,12 +199,12 @@ It could coalesce writes into a single buffer that can then be transmitted atomi And much more. In fact, this pattern appears often in the standard library. -The [[https://golang.org/pkg/archive/zip/][`archive/zip`]] and -[[https://golang.org/pkg/net/http/][`net/http`]] packages use it. -More salient to this discussion, the [[https://golang.org/pkg/bufio/][`bufio` package's `Writer`]] +The [`archive/zip`](https://golang.org/pkg/archive/zip/) and +[`net/http`](https://golang.org/pkg/net/http/) packages use it. +More salient to this discussion, the [`bufio` package's `Writer`](https://golang.org/pkg/bufio/) is actually an implementation of the `errWriter` idea. Although `bufio.Writer.Write` returns an error, -that is mostly about honoring the [[https://golang.org/pkg/io/#Writer][`io.Writer`]] interface. +that is mostly about honoring the [`io.Writer`](https://golang.org/pkg/io/#Writer) interface. The `Write` method of `bufio.Writer` behaves just like our `errWriter.write` method above, with `Flush` reporting the error, so our example could be written like this: @@ -231,5 +232,5 @@ Use the language to simplify your error handling. But remember: Whatever you do, always check your errors! -Finally, for the full story of my interaction with @jxck_, including a little video he recorded, -visit [[http://jxck.hatenablog.com/entry/golang-error-handling-lesson-by-rob-pike][his blog]]. +Finally, for the full story of my interaction with @jxck\_, including a little video he recorded, +visit [his blog](http://jxck.hatenablog.com/entry/golang-error-handling-lesson-by-rob-pike). |