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The meaning of this (lemmy.world)

submitted 2 months ago by cm0002@lemmy.world to c/programmer_humor@programming.dev

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[-] TootSweet@lemmy.world 26 points 2 months ago

Go:

MCU universe Loki saying "I've never met this man in my life."

[-] mindbleach@sh.itjust.works 21 points 2 months ago

"We wanted it to work like Perl," said someone who should have been killed on the spot.

[-] palordrolap@fedia.io 9 points 2 months ago

At the time JS was created, Perl didn't have a this. A lot of the docs and books suggested using $self but a reference to the object would be passed as the first parameter to all class methods and you assign that to any name you wanted.

It's only very recently (as in the last year or so) with a new class system that Perl has hard-coded $self for that purpose.

[-] mindbleach@sh.itjust.works 4 points 2 months ago

I mean $_.

[-] palordrolap@fedia.io 2 points 2 months ago

Ah. The usually implicit topical "this" didn't even occur to me because I thought, er, this, was about objects. $_ isn't used for those in Perl.

I suppose there might be some parallels with the implicit nature of $_ in non-OO contexts in Perl versus this in OO contexts in Javascript, but, at least to me, that feels pretty tenuous.

[-] nnullzz@lemmy.world 12 points 2 months ago

Yeah, this is that.

[-] sourhill@lemmy.sdf.org 12 points 2 months ago

const that = this;

[-] fnrir@lemmy.blahaj.zone 8 points 2 months ago

Rust: do you mean Self or self?

[-] d_k_bo@feddit.org 6 points 2 months ago* (last edited 2 months ago)

this is commonly used with a similar meaning to self in cases where self can't be used because it is a reserved keyword.

Example:

    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<St1::Item>> {
        let this = self.project();
        this.inner.poll_next(cx)
    }

https://github.com/rust-lang/futures-rs/blob/master/futures-util/src/stream/select.rs#L113-L116