Problem with dereferencing and namespaces in Rust | Rust Programming Language Community | Page 1

fervent current Jul 15, 2022, 12:23 AM

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Hello, I am having issues with dereferencing. Coming from C++ background, decided to write a GUI toolkit in Rust, started today, like 1h ago. Here's the context.

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Besides, I just got this. How am I supposed to fix this?

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Problem with dereferencing and namespaces in Rust

warm path Jul 15, 2022, 12:48 AM

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fervent current Hello, I am having issues with dereferencing. Coming from C++ background, decide...

first of all

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try putting in the loop

"for .. in .."

something like this

"for &.. in .."

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because its expecting the struct

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and you are giving a reference to it

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when you put "&" before loop assing then it dereferences

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in your case:

for /*notice the "&" -->*/ &m in connected {
  monitors.push(m);
}

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if m doesnt implements Copy then try taking ownership of connected instead

fervent current Jul 15, 2022, 12:54 AM

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ooo yes yes

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thanks

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I fixed the other problem

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with the Window thing

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also made them lowercase

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to follow convention

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Now this error

warm path Jul 15, 2022, 12:57 AM

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warm path if m doesnt implements Copy then try taking ownership of connected instead

yes it doesnt implements Copy

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let me think

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mmm

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what type is connected_monitors?

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@fervent current

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is it reference?

fervent current Jul 15, 2022, 1:04 AM

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let me see quickly again

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An opaque handle

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&[window::droplet_window::glfw::Monitor]

warm path Jul 15, 2022, 1:05 AM

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that is the type of m

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right?

fervent current Jul 15, 2022, 1:06 AM

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warm path that is the type of m

that's the connected_monitors

warm path Jul 15, 2022, 1:06 AM

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but the error code says that is the type of m

fervent current Jul 15, 2022, 1:06 AM

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And the type of m is window::droplet_window::glfw::Monitor

warm path Jul 15, 2022, 1:06 AM

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ahhhh

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ok

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i miss read

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they didnt give the ownership

fervent current Jul 15, 2022, 1:07 AM

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yes, so what shall I do?

warm path Jul 15, 2022, 1:08 AM

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does window::droplet_window::glfw::Monitor implements Clone?

fervent current Jul 15, 2022, 1:08 AM

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no it does not

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You meant the Copy trait, but neither

warm path Jul 15, 2022, 1:09 AM

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no

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Clone is different

fervent current Jul 15, 2022, 1:09 AM

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when I do .clone() it still underlines it

warm path Jul 15, 2022, 1:10 AM

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do you really need to have a vector of owned window::droplet_window::glfw::Monitor?

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or you just need the reference

fervent current Jul 15, 2022, 1:10 AM

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Reference is fine

warm path Jul 15, 2022, 1:10 AM

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then make the vector of references instead owned

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its cheaper in memory too

fervent current Jul 15, 2022, 1:12 AM

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Lifetime issue

warm path Jul 15, 2022, 1:12 AM

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i was expecting it

fervent current Jul 15, 2022, 1:14 AM

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Now I removed the reference from for &m

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but I still get this

warm path Jul 15, 2022, 1:14 AM

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you are dropping glfw before monitors

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probably

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no, connected_monitors is in clousure

fervent current Jul 15, 2022, 1:15 AM

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Here, to get a fuller picture

warm path Jul 15, 2022, 1:16 AM

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i think you can remove that & right?

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m its self is &

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it will not help anyways

fervent current Jul 15, 2022, 1:16 AM

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yeah

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I removed it

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nothing changed

warm path Jul 15, 2022, 1:17 AM

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i k but it makes it cleaner

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wait

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you are using monitor

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but you never assign it

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monitor without s

fervent current Jul 15, 2022, 1:18 AM

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This might be helping

fervent current Jul 15, 2022, 1:18 AM

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warm path but you never assign it

That's for later

warm path Jul 15, 2022, 1:18 AM

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its a start but is not the problem

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ye

fervent current Jul 15, 2022, 1:18 AM

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Another way is I just spawn everything on the primary monitor

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But that will make things very limiting

warm path Jul 15, 2022, 1:19 AM

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the problem is

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if you save it like reference

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its dropped and you get danging reference

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and the compiler knows it

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and you cant owned because the library doesnt allow you to copy it, that is maybe obvious because its monitor handling

fervent current Jul 15, 2022, 1:21 AM

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https://docs.rs/glfw/latest/glfw/struct.Glfw.html#method.with_primary_monitor

There is this method, for the primary monitor

Glfw in glfw - Rust

A token from which to call various GLFW functions. It can be obtained by calling the init function. This cannot be sent to other tasks, and should only be initialized on the main platform thread. Whilst this might make performing some operations harder, this is to ensure thread safety is enforced statically.

warm path Jul 15, 2022, 1:22 AM

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i think the only way is only using monitors inside the clousure

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its not about satisfying the compiler

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its about dangling references

fervent current Jul 15, 2022, 1:23 AM

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Well, I can make it select the monitor and then create the window inside it

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I just have no idea how to know about a monitor's name at run time

warm path Jul 15, 2022, 1:23 AM

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why do you need a vector of them?

fervent current Jul 15, 2022, 1:24 AM

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I thought it'd let me select the monitor they ran it from

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Because the Rust crate only exports two things

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Shall I just do "with primary monitor"

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and roll with it

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It's always possible to go back at this later and fix it

warm path Jul 15, 2022, 1:26 AM

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i think saving monitors can result in errors, and maybe that is because you can

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try
monitors = connected_monitors.to_vec();

fervent current Jul 15, 2022, 1:27 AM

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this is the C library itself

warm path Jul 15, 2022, 1:28 AM

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what you want to index them?

fervent current Jul 15, 2022, 1:29 AM

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fervent current Jul 15, 2022, 1:30 AM

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warm path what you want to index them?

I would use them into a struct called DropletDisplay

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Where I can label them with names such as "Display1" (primary display)

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and so on

warm path Jul 15, 2022, 1:30 AM

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then why you want to make a vector of monitors?

fervent current Jul 15, 2022, 1:30 AM

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fervent current I would use them into a struct called DropletDisplay

I meant monitor

warm path Jul 15, 2022, 1:31 AM

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looks like the library only wants to give you the monitors inside the function .with_connected_monitors

fervent current Jul 15, 2022, 1:32 AM

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fervent current Jul 15, 2022, 1:32 AM

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warm path looks like the library only wants to give you the monitors inside the function ....

That's kinda shitty

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Because I want to let people to select a monitor

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where this opens

warm path Jul 15, 2022, 1:33 AM

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worry i want to help but i want to go to dinner

fervent current Jul 15, 2022, 1:33 AM

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We can talk later

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It's ok

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I will be awake

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it's just 4:33

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I am just starting

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Feel free to DM too

warm path Jul 15, 2022, 1:33 AM

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here its 22:33

fervent current Jul 15, 2022, 1:33 AM

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Easier to get real time to you

fervent current Jul 15, 2022, 1:33 AM

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warm path here its 22:33

oooh american

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using 24h

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perfect

warm path Jul 15, 2022, 1:33 AM

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ye

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arg

fervent current Jul 15, 2022, 1:34 AM

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Enjoy your dinner

warm path Jul 15, 2022, 2:34 AM

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@fervent currenti came back

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are you sure your api cant give you a vector of monitors?

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or &[monitors] but independent of a clousure?

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if not probably there is a reason because it doesn't exist, maybe API wants to be secure when you are not using monitors anymore

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https://docs.rs/glfw/0.13.0/glfw/ffi/fn.glfwGetMonitors.html

glfw::ffi::glfwGetMonitors - Rust

API documentation for the Rust glfwGetMonitors fn in crate glfw.

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you can use this (like in C++)

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but its unsafe (like in C++)

fervent current Jul 15, 2022, 2:42 AM

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welcome back

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ok so

fervent current Jul 15, 2022, 2:43 AM

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warm path if not probably there is a reason because it doesn't exist, maybe API wants to b...

I decided on a better implementation in the future

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for now I will just use primary monitor

warm path Jul 15, 2022, 2:45 AM

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warm path https://docs.rs/glfw/0.13.0/glfw/ffi/fn.glfwGetMonitors.html

anyways this works right?

fervent current Jul 15, 2022, 2:47 AM

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warm path anyways this works right?

The crate forbids it

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as far as I know

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Why this now...

warm path Jul 15, 2022, 2:58 AM

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fervent current Why this now...

what happend

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why 2 of the matched has the same code?

fervent current Jul 15, 2022, 3:00 AM

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warm path why 2 of the matched has the same code?

Because the thing only has Windowed mode

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and I will do something later

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with Borderless

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I will set decoration to false

warm path Jul 15, 2022, 3:01 AM

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oh ok srry unfinished code is confusing

fervent current Jul 15, 2022, 3:01 AM

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It's finished in this match

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I will be elaborated after making the window

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because there is no other way.

warm path Jul 15, 2022, 3:02 AM

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anyways

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what is thee problem

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in line 69 - 1

fervent current Jul 15, 2022, 3:02 AM

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How can I make a value leave a closure?

warm path Jul 15, 2022, 3:02 AM

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fervent current How can I make a value leave a closure?

you can, when it leaves the clousure the value doesnt exist anymore

fervent current Jul 15, 2022, 3:02 AM

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droplet_window.rs(56, 21): window_mode declared here, outside of the closure body
droplet_window.rs(66, 60): monitor is a reference that is only valid in the closure body
droplet_window.rs(68, 33): monitor escapes the closure body here

warm path Jul 15, 2022, 3:03 AM

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basically

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you setted

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window_mode = &monitor

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right?

fervent current Jul 15, 2022, 3:04 AM

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no

warm path Jul 15, 2022, 3:04 AM

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what

fervent current Jul 15, 2022, 3:04 AM

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I set window_mode to FullScreen on monitor at &monitor

warm path Jul 15, 2022, 3:04 AM

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well yes

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but its derivated

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by lifetime

fervent current Jul 15, 2022, 3:04 AM

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can I extend its lifetime?

warm path Jul 15, 2022, 3:05 AM

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no lifetime doesn't change when it drops

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basically if you were doing this in another language

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like C

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C would let you do it

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but you will have terrible errors

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terrible

fervent current Jul 15, 2022, 3:06 AM

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When a value leaves scope, C doesn't let you compile

warm path Jul 15, 2022, 3:06 AM

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so when you set windows_mode

warm path Jul 15, 2022, 3:06 AM

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fervent current When a value leaves scope, C doesn't let you compile

its not the same

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wait

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what C compiler are you using

fervent current Jul 15, 2022, 3:07 AM

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clang (LLVM)

warm path Jul 15, 2022, 3:07 AM

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well no C will let you

fervent current Jul 15, 2022, 3:07 AM

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I also use gcc

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both don't let you

warm path Jul 15, 2022, 3:07 AM

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any C compiler detect that anyways

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basically you set
window_mode to a &monitor derivated

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when you drop monitor

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monitor derivated is unvalid

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if you use it is UB

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and you will likely get a unvalid object

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you have 2 options

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use some unsafe API

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or cobber all function with that closure

fervent current Jul 15, 2022, 3:10 AM

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warm path or cobber all function with that closure

The entire thing in new() ?

warm path Jul 15, 2022, 3:10 AM

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https://docs.rs/glfw/0.13.0/glfw/ffi/fn.glfwGetPrimaryMonitor.html
unsafe func

glfw::ffi::glfwGetPrimaryMonitor - Rust

API documentation for the Rust glfwGetPrimaryMonitor fn in crate glfw.

fervent current Jul 15, 2022, 3:10 AM

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Or the entire droplet_window.rs file ?

warm path Jul 15, 2022, 3:10 AM

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fervent current The entire thing in new() ?

yes you probably dont want that

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no sorry

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in entire zone where you need it

warm path Jul 15, 2022, 3:11 AM

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warm path https://docs.rs/glfw/0.13.0/glfw/ffi/fn.glfwGetPrimaryMonitor.html unsafe func

but you can use the unsafe version too

fervent current Jul 15, 2022, 3:11 AM

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So the entire thing in new okay

warm path Jul 15, 2022, 3:11 AM

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that will let you do it more idiomatic at your risk

fervent current Jul 15, 2022, 3:11 AM

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(apart from the return which is Self)

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I'd rather keep it safe for now

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if at some point it gets hard

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I will use ffi

warm path Jul 15, 2022, 3:12 AM

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ye i recommend you safe

fervent current Jul 15, 2022, 3:12 AM

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You probably understood what I am making when I shared my screen

warm path Jul 15, 2022, 3:12 AM

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because when you have a really hard problem

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uf

fervent current Jul 15, 2022, 3:16 AM

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This is a mess

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If this makes me lose my patience

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I will code it in C++

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and let it be

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because this is too much effort for literally nothing

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I can always make myself a Rust wrapper

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after C++

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I have a vague idea of what I can do

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but this api is just a mess

warm path Jul 15, 2022, 3:24 AM

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@fervent currentbut why not just use the unsafe version

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its the same as C++ one

warm path Jul 15, 2022, 3:25 AM

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warm path https://docs.rs/glfw/0.13.0/glfw/ffi/fn.glfwGetPrimaryMonitor.html unsafe func

.

fervent current Jul 15, 2022, 3:26 AM

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warm path <@713411619895509112>but why not just use the unsafe version

Because it makes no sense to do so in a safe API

warm path Jul 15, 2022, 3:26 AM

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yes

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sometimes unsafe is needed

fervent current Jul 15, 2022, 3:26 AM

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I'd only do it if I am really ahead and I cannot allow myself to change the language

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I am trying something

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give me a sec

warm path Jul 15, 2022, 3:27 AM

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post the entire new func

fervent current Jul 15, 2022, 3:31 AM

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fn new (title: &str,
        dimensions: (u32, u32),
        decorations: DropletWindowDecorations,
        state: (DropletWindowMinimisedState, DropletWindowFocusedState),
        mode: DropletWindowMode) -> Self
            {
                let mut glfw = glfw::init(glfw::FAIL_ON_ERRORS).unwrap();

                match &mode {
                    DropletWindowMode::Bordered => {
                        let (mut window, events) = glfw.create_window
                                            (dimensions.0, dimensions.1, title,
                                                glfw::WindowMode::Windowed)
                                                .expect("Cannot create window.");
                    },
                    DropletWindowMode::Borderless => {
                        let (mut window, events) = glfw.create_window
                                            (dimensions.0, dimensions.1, title,
                                                glfw::WindowMode::Windowed)
                                                .expect("Cannot create window.");
                        
                                                window.set_decorated(false);
                    },
                    DropletWindowMode::Fullscreen => {
                        let (mut window, events) = glfw.with_primary_monitor(|_, mon|
                            {
                                glfw.create_window
                                            (dimensions.0, dimensions.1, title,
                                            glfw::WindowMode::FullScreen(&mon.unwrap()))
                                            .expect("Cannot create window.")
                            });
                    }
                }

                Self {
                    title: title.to_owned(),
                    dimensions,
                    decorations,
                    state,
                    mode,
                    view: None
                }
    }

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But I am still getting the same error

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Actually, if this keeps on bugging me

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I will just make this a borderless window

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with the size of the actual display

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and make it unmovable

warm path Jul 15, 2022, 3:32 AM

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dont change your plans

fervent current Jul 15, 2022, 3:34 AM

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The fuck of an API literally

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I give up, I am done for today

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2 hours spent on this

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I am literally following the example of this dude

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He himself doesn't know how to use his API

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I am done man

warm path Jul 15, 2022, 3:37 AM

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you will do it with borderless and bordered?

fervent current Jul 15, 2022, 3:37 AM

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No, I will use fullscreen

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but I will not use his full screen

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I will use only Windowed from the API

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but I will disable borders

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and set the size to the display size

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why do I need a monitor setup in my toolkit?

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haha

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I can just use displays

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isn't that better

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unless...

warm path Jul 15, 2022, 3:38 AM

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fervent current I am literally following the example of this dude

which dude?

fervent current Jul 15, 2022, 3:38 AM

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the one who made the rust wrapper

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See the big Example letters?

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That's written by him

warm path Jul 15, 2022, 3:39 AM

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anyways did you tried the unsafe one?

fervent current Jul 15, 2022, 3:39 AM

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no, I haven't

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maybe later

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It's 6:40

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I am so angry that I won't go to sleep

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I want to fix this

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but I am tired to do so

warm path Jul 15, 2022, 3:40 AM

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i want to help but i dont wanna ask for entire code

fervent current Jul 15, 2022, 3:41 AM

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It's going to be open source

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lol

warm path Jul 15, 2022, 3:41 AM

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lol

fervent current Jul 15, 2022, 3:41 AM

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I will legit commit to github now

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I am making a toolkit for my OS

warm path Jul 15, 2022, 3:41 AM

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LOL

fervent current Jul 15, 2022, 3:41 AM

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I want to make a Desktop Environment with it

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and apps

warm path Jul 15, 2022, 3:41 AM

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are you making a OS?

fervent current Jul 15, 2022, 3:41 AM

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yes

warm path Jul 15, 2022, 3:41 AM

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wow

fervent current Jul 15, 2022, 3:41 AM

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FreeBSD based

warm path Jul 15, 2022, 3:41 AM

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good luck

fervent current Jul 15, 2022, 3:42 AM

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I am using a high level API, and maybe that's my mistake

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But if I use Vulkan directly

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it's overwhelming

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and one person cannot make this

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without abstractions

warm path Jul 15, 2022, 3:42 AM

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how big is the code rn?

fervent current Jul 15, 2022, 3:42 AM

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It's actually just this

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I started today

warm path Jul 15, 2022, 3:43 AM

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ok pass the entire code if you want and i will find the way

fervent current Jul 15, 2022, 3:43 AM

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And I thought "best to start with the Windows, then Widgets"

fervent current Jul 15, 2022, 3:43 AM

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warm path ok pass the entire code if you want and i will find the way

I will commit to GitHub and send a link

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I will do so on DM if you want

warm path Jul 15, 2022, 3:43 AM

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ok

fervent current Jul 15, 2022, 3:43 AM

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I am going to commit this at its current version

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Are you really interested in contributing?

warm path Jul 15, 2022, 3:44 AM

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or advise me when you upload

warm path Jul 15, 2022, 3:44 AM

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fervent current Are you really interested in contributing?

ye

fervent current Jul 15, 2022, 3:44 AM

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thanks a lot

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We can work together? If you wanna have fun of course

warm path Jul 15, 2022, 3:44 AM

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i dont know anything about OS dev

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im sorry

fervent current Jul 15, 2022, 3:44 AM

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Just the toolkit

warm path Jul 15, 2022, 3:44 AM

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ok

fervent current Jul 15, 2022, 3:44 AM

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everything else I know what to do

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Since we have guys who have the task to make hardware

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They will make a processor architecture as well

warm path Jul 15, 2022, 3:45 AM

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wait

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that is a lot actually

fervent current Jul 15, 2022, 3:46 AM

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It is, yes

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We thought about using RISC-V initially

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But well, we might need a fuller instruction set

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and x86 is closed source

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we want to make everything open source

warm path Jul 15, 2022, 3:46 AM

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how is the OS called?

fervent current Jul 15, 2022, 3:46 AM

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Fluid

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It will be an OS for phones, computers, tablets, TVs and even smartwatches/any wearables

warm path Jul 15, 2022, 3:47 AM

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wow that is impressive

fervent current Jul 15, 2022, 3:48 AM

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The goal is to make it as beautiful, stable and user-friendly as possible

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but also accommodating to developers

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hence why I chose FreeBSD

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FreeBSD is better for development than Linux in my opinion

warm path Jul 15, 2022, 3:48 AM

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by the name i can make assumptions about his appearance

fervent current Jul 15, 2022, 3:48 AM

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But I like both

fervent current Jul 15, 2022, 3:48 AM

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warm path by the name i can make assumptions about his appearance

What do you imagine?

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I have an unfinished basic concept

warm path Jul 15, 2022, 3:49 AM

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lightblue

fervent current Jul 15, 2022, 3:49 AM

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from our designer

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Sure, the colours are blue

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Come on DM since this got off topic

#Problem with dereferencing and namespaces in Rust