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  • Author Author: clem57
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New feature in Python 3.8

clem57

     Even though Python 3.8 is not official releases, there have been a few Alpha versions floating around. There are some interesting ideas in these including one called a Walrus Operator.

Here is the explanation:

 

Walrus-operator is another name for assignment expressions. According to the official documentation, it is a way to assign to variables within an expression using the notation NAME := expr. The Assignment expressions allow a value to be assigned to a variable, even a variable that doesn’t exist yet, in the context of expression rather than as a stand-alone statement.

This can make a longer expression be shortened with in the context of the assignment. For example:

sample_data = [ 
    {"userId": 1,  "name": "rahul", "completed": False}, 
    {"userId": 1, "name": "rohit", "completed": False}, 
    {"userId": 1,  "name": "ram", "completed": False}, 
    {"userId": 1,  "name": "ravan", "completed": True} 
] 

print("With Python 3.8 Walrus Operator:")  
for entry in sample_data:  
    if name := entry.get("name"): 
        print(f'Found name: "{name}"')

 

Here is the same without using Walrus:

 

print("Without Walrus operator:")

for entry in sample_data:
    name =entry.get("name")
    if name:
        print(f'Found name: "{name}"')

 

Please comment if you thing this is a good change or not. Discuss the reasons why or why not...

  • I learned to program in the early 70s - ALGOL on an Elliot 803!

     

    My teachers drummed into me the importance of readability, simplicity of expression and comments.

     

    I have never forgotten that.

     

    I agree about readability, but the new style of camel case, etc just does not come too easily. Oh well, I will just have to adjust as best I can.image

    Clem

  • at first sight, it looks like comparison operator.

    it saves one line, with reduce readability. i will still stick with the one without walrus operator.

    i dont know if it is a good change, may be someday i will need it.

  • in reply to ntewinkel

      wrote:

     

     

    I kind of prefer the readability of keeping things separate.

     

    Going back to the days of C, I recall some programmers chunking entire functions into a single line which only made sense to the most advanced programmers but made it completely illegible to anyone else.

    To me, that's bad style. At some point a junior programmer will need to read your code. Or worse - you might need to read your OWN code a few years later to support it image

     

    I learned to program in the early 70s - ALGOL on an Elliot 803!

     

    My teachers drummed into me the importance of readability, simplicity of expression and comments.

     

    I have never forgotten that.

     

    Neil

  • I can see the utility in testing incomplete programs.

     

    DAB

  • That seems to be a convergence to what other languages are doing.

     

    The same thing in Swift looks like this:

     

    let sample_data: [[String: Any]] = [
    ["userId": 1,  "name": "rahul", "completed": false],
    ["userId": 1, "name": "rohit", "completed": false],
    ["userId": 1,  "name": "ram", "completed": false],
    ["userId": 1,  "name": "ravan", "completed": false]
]
  
print("Swift output")
for entry in sample_data {
    if let name = entry["name"] {
        print("found name: \(name)")
    }
}

     

    With lots of subtle and annoying syntax differences between all languages. arg.

     

    I kind of prefer the readability of keeping things separate.

    It also allows you to easily add a debug log statement in between the assignment and the if statement, if something comes up in the future.

     

    Going back to the days of C, I recall some programmers chunking entire functions into a single line which only made sense to the most advanced programmers but made it completely illegible to anyone else.

    To me, that's bad style. At some point a junior programmer will need to read your code. Or worse - you might need to read your OWN code a few years later to support it image

     

    What's the reason for so many languages anyway? To me it seems to be very political, including patent pirates making life difficult.

    For example, it looks like for Android development, Java is being replaced by Kotlin now because Oracle is starting to charge for the use of Java.

    I might be interpreting that Kotlin move wrong.

     

    Of course, I guess there's always just the fact that many people have many different preferences.

     

    Cheers,

    -Nico