An import declaration lets you access symbols that are declared outside the current file. The basic form imports the entire module; it consists of the import keyword followed by a module name:
import module
Providing more detail limits which symbols are imported—you can specify a specific submodule or a specific declaration within a module or submodule.
But how can I know which module the URL class belongs to ? We can just search this in Google:
By default, when all top-level code is executed, the execution is terminated. When working with asynchronous code, enable indefinite execution to allow execution to continue after the end of the playground’s top-level code is reached. This, in turn, gives threads and callbacks time to execute.
We set this flag because we have an asynchronous process that would wait for the URL to be accessed and process the response, just as follows:
let task = URLSession.shared.dataTask(with: url) {(data, response, error) in
guardlet data = data else { return }
print(String(data: data, encoding: .utf8)!)
}
In the above code, we passed a closure function to the dataTask function to process the URL response when the connection succeeded.
let url =URL(string: "http://www.stackoverflow.com")!
let task = URLSession.shared.dataTask(with: url) {(data, response, error) in
guardlet data = data else { return }
print(String(data: data, encoding: .utf8)!)
}
task.resume()
Now it works!
4. Summary
In this post, I demonstrated how to solve the ‘cannot find class in scope’ error in xcode playground, be sure to check you have imported the classes you are using .
Shutil module in Python provides many functions of high-level operations on files and collections of files. … This module helps in automating process of copying and removal of files and directories. shutil. copy() method in Python is used to copy the content of source file to destination file or directory.
Shutil is the abbreviation of shell utility, which implements advanced functions such as file copying, moving, compression, and decompression in Python. It is a Python system module and does not require additional installation.
The commonly used functions in shutil are listed below:
shutil.copyfile(src, dst) Copy from source src to dst. Of course, the premise is that the target address has writable permissions. The exception information thrown is IOException. If the current dst already exists, it will be overwritten
shutil.move(src, dst) move file or rename
shutil.copymode(src, dst) just copy its permissions and other things will not be copied
shutil.copystat(src, dst) copy permission, last access time, last modification time
shutil.copy(src, dst) copy a file to a file or a directory
shutil.copy2(src, dst) is copied on the basis of copy and the last access time and modification time of the file are also copied, similar to cp -p
shutil.copy2(src, dst) If the file systems in the two locations are the same, it is equivalent to a rename operation, just rename; if it is not in the same file system, it is a move operation
shutil.copytree(olddir, newdir, True/Flase) copies olddir to newdir. If the third parameter is True, the symbolic link under the folder will be kept when copying the directory. If the third parameter is False, it will Generate a physical copy in the copied directory to replace the symbolic link
shutil.rmtree(src) recursively delete a directory and all contents in the directory
5. Summary
In this post, I demonstrated how to use shutil in python to copy files from here to there. And I also demonstrated how to avoid overwriting the dest file when copying. Thanks for your reading. Regards.
In Kubernetes (K8s), volumeClaimTemplates is a resource template used within StatefulSets to dynamically create persistent storage volumes (Persistent Volumes, PVs). VolumeClaimTemplates allow each Pod within a StatefulSet to have its own independent persistent storage, and PVCs (Persistent Volume Claims) corresponding to them can be automatically created through the template.
The role of volumeClaimTemplates:
Automate PVC creation: VolumeClaimTemplates enable you to automatically create PVCs for each Pod in a StatefulSet without manually configuring a PVC for each Pod. This is particularly useful for applications that require each Pod to have its own independent storage.
Ensure persistent storage: StatefulSets are primarily used for stateful applications (such as databases, distributed systems, etc.), which require ensuring that storage is not lost in cases of Pod restarts, migrations, etc. With volumeClaimTemplates, each Pod has its own PVC and mounted PV, ensuring data persistence.
Automatic binding of Persistent Volume (PV): Kubernetes automatically creates PVCs based on volumeClaimTemplates, and these PVCs are automatically bound to a suitable PV. This means that users do not need to manually manage the relationship between PVCs and PVs; Kubernetes automatically selects the appropriate PV based on storage resources and configured StorageClass.
Templated storage configuration: When using volumeClaimTemplates, you can define a template for PVCs (such as storage size, storage class, etc.), and Kubernetes will create corresponding PVCs for each Pod. This ensures that all Pods use the same storage configuration without the need to define storage details for each Pod individually.
But,
StatefulSet is useful for running things in cluster e.g Hadoop cluster, MySQL cluster, where each node has its own storage.
Solution
You can switch from Deployment to StatefulSet as follows:
