Hi Mirmojtaba, thanks for your suggestion.

I doubt this idea will fly with this syntax because it could easily be confused with the walrus operator. x := 0 is *almost* legal syntax currently.  In fact (x := 0) is legal, and it is quite possible that at some time in the future     (Dic[fruit]:=0) will also be made legal.

Your particular example can be written

Dic = {} for fruit in fruits:     Dic[fruit] = Dic.get(fruit, 0) + 1 # 0 is default value if key not in dict

Actually I can see this idea being more useful with ordinary variables. At the moment we can write something like this:

try:     count = count + 1 except NameError: # count has not been initialised yet     count = 1

which is fairly clumsy, and with your idea would be more concise:

count := 0    # or a different syntax, maybe count <== 0 or something     count += 1

(NB In fact if PEP 463 "Exception-catching expressions" had been accepted, we could write something like     count = count + 1 except NameError: 1 but the PEP has been rejected, regrettably in my opinion. 🙁)

That said, in most real examples, one could write     count = 0 initially, and     count = count +1 to increment.

So I think it is up to you to provide further convincing examples in favour of your idea. Best wishes Rob Cliffe

On 05/02/2022 20:18, Mirmojtaba Gharibi wrote:

Hello there,

I have an idea for initializing a variable the first time it’s created; it can especially be helpful with containers, and dicts specifically. Let me demonstrate with some examples:

Dic = {} # format fruit:count for fruit in fruits:    If fruit in Dic:       Dic[fruit]+=1    Else:       Dic[fruit]=1

With my proposal, using := to init (similar to how in math parlance, the := is used for defining something for the first time)

Dic =  {} # format fruit:count For fruit in fruits:    Dic[fruit]:= 0    Dic[fruit]+=1

Would be great to hear your feedback. Thanks.

Moj

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