Understanding err.(*os.PathError) in Go
In Go's documentation on effective error handling (https://golang.org/doc/effective_go.html#errors), you may have encountered the code snippet:
<code class="go">for try := 0; try < 2; try++ { file, err = os.Create(filename) if err == nil { return } if e, ok := err.(*os.PathError); ok && e.Err == syscall.ENOSPC { deleteTempFiles() // Recover some space. continue } return }</code>
This code demonstrates the use of err.(*os.PathError). Let's delve into what it means.
What is err.(*os.PathError)?
When os.Create is called, it returns an error as its second return value. This error implements the error interface { Error() string }. Any data type that possesses an Error method can implement this interface and be assigned to it.
Typically, simply outputting the error message suffices. However, in the given example, the program aims to handle the ENOSPC (no space left on device) error specifically. The os package provides an *os.PathError as the error implementation in such cases. If you need to access further information about the error, you can cast it.
Type Assertion: e, ok := err.(*os.PathError)
The statement e, ok := err.(os.PathError) employs type assertion. It verifies if the interface value err holds a os.PathError as its concrete type, and if so, it returns that value. If a different type is present in the interface (other types may also implement the error interface), it simply returns the zero value and false (nil, false in this case).
The above is the detailed content of When and Why Use `err.(*os.PathError)` in Go?. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undress AI Tool
Undress images for free

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics









TointegrateGolangserviceswithexistingPythoninfrastructure,useRESTAPIsorgRPCforinter-servicecommunication,allowingGoandPythonappstointeractseamlesslythroughstandardizedprotocols.1.UseRESTAPIs(viaframeworkslikeGininGoandFlaskinPython)orgRPC(withProtoco

Golangofferssuperiorperformance,nativeconcurrencyviagoroutines,andefficientresourceusage,makingitidealforhigh-traffic,low-latencyAPIs;2.Python,whileslowerduetointerpretationandtheGIL,provideseasierdevelopment,arichecosystem,andisbettersuitedforI/O-bo

Golang is mainly used for back-end development, but it can also play an indirect role in the front-end field. Its design goals focus on high-performance, concurrent processing and system-level programming, and are suitable for building back-end applications such as API servers, microservices, distributed systems, database operations and CLI tools. Although Golang is not the mainstream language for web front-end, it can be compiled into JavaScript through GopherJS, run on WebAssembly through TinyGo, or generate HTML pages with a template engine to participate in front-end development. However, modern front-end development still needs to rely on JavaScript/TypeScript and its ecosystem. Therefore, Golang is more suitable for the technology stack selection with high-performance backend as the core.

TocompletelyuninstallGolang,firstdeterminehowitwasinstalled(packagemanager,binary,source,etc.),thenremoveGobinariesanddirectories,cleanupenvironmentvariables,anddeleterelatedtoolsandcaches.Beginbycheckinginstallationmethod:commonmethodsincludepackage

In Go language, channel is used for communication and synchronization between goroutines. Declare the use of make function, such as ch:=make(chanstring), send the ch

When encountering a "cannotfindpackage" error, it is usually because Go cannot find the target package or dependency. The solution is as follows: 1. Check whether the import path is correct and ensure that it is consistent with the module path or directory structure; 2. Confirm that the go.mod file has been initialized and use gomodinit and gomodtidy to manage dependencies; 3. Run goget to download missing dependencies or clean the module cache; 4. Make sure to execute commands in the correct directory context, or specify the complete module relative path for construction.

In Go, using select statements can effectively handle non-blocking channel operations and implement timeout mechanisms. Non-blocking reception or sending operations are realized through the default branch, such as 1. Non-blocking reception: if there is a value, it will be received and printed, otherwise the default branch will be executed immediately; 2. Non-blocking transmission: If there is no receiver in the channel, the sending will be skipped. In addition, timeout control can be implemented in conjunction with time.After, such as waiting for the result or returning after 2 seconds. You can also combine non-blocking and timeout behaviors, try to get the value immediately, and wait for a short time after failure, so as to improve the program's concurrent response capabilities.

In Go, if you want the structure field to use a custom field name when converting to JSON, you can implement it through the json tag of the structure field. 1. Use the json: "custom_name" tag to specify the key name of the field in JSON. For example, Namestringjson: "username"" will make the Name field output as "username"; 2. Add, omitempty can control that the output is omitted when the field is empty, such as Emailstringjson: "email,omitempty""
