this post was submitted on 20 Dec 2024
974 points (96.9% liked)

Programmer Humor

32751 readers
75 users here now

Post funny things about programming here! (Or just rant about your favourite programming language.)

Rules:

founded 5 years ago
MODERATORS
 
you are viewing a single comment's thread
view the rest of the comments
[โ€“] pooberbee@lemmy.ml 1 points 1 week ago (1 children)

Yeah, you would get a runtime error calling that member without checking that it exists.

[โ€“] masterspace@lemmy.ca 1 points 6 days ago* (last edited 3 days ago)

Because that object is of a type where that member may or may not exist. That is literally the exact same behaviour as Java or C#.

If I cast or type check it to make sure it's of type Bar rather than checking for the member explicitly it still works:

And when I cast it to Foo it throws a compile time error, not a runtime error:

I think your issues may just like in the semantics of how Type checking works in JavaScript / Typescript.