Why does joining paths completely replace the original path in Rust?

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I don't understand how Rust concatenates file paths. Why doesn't this work:

fn main() {

    let root = std::path::Path::new("resources/");

    let uri = std::path::Path::new("/js/main.js");

    let path = root.join(uri);

    assert_eq!(path.to_str(), Some("resources/js/main.js"));

}

fails with:

thread 'main' panicked at 'assertion failed: `(left == right)`

  left: `Some("/js/main.js")`,

 right: `Some("resources/js/main.js")`', src/main.rs:5:5

I see in the docs that "pushing an absolute path replaces the existing path", but this seems like a terrible idea that will catch a lot of people.

In that case, how do I safely strip the absolute path, or make it relative?

edited Nov 22 '18 at 21:24

Shepmaster

163k16337483

asked Nov 22 '18 at 11:50

Petrus Theron

13.5k24114227

1

I guess you can see this: github.com/rust-lang/rust/issues/16507 discussion

– Stoogy
Nov 22 '18 at 12:05

@Stoogy thanks; I've commented on the issue.

– Petrus Theron
Nov 22 '18 at 17:28

add a comment |

I don't understand how Rust concatenates file paths. Why doesn't this work:

fn main() {

    let root = std::path::Path::new("resources/");

    let uri = std::path::Path::new("/js/main.js");

    let path = root.join(uri);

    assert_eq!(path.to_str(), Some("resources/js/main.js"));

}

fails with:

thread 'main' panicked at 'assertion failed: `(left == right)`

  left: `Some("/js/main.js")`,

 right: `Some("resources/js/main.js")`', src/main.rs:5:5

I see in the docs that "pushing an absolute path replaces the existing path", but this seems like a terrible idea that will catch a lot of people.

In that case, how do I safely strip the absolute path, or make it relative?

edited Nov 22 '18 at 21:24

Shepmaster

163k16337483

asked Nov 22 '18 at 11:50

Petrus Theron

13.5k24114227

1

I guess you can see this: github.com/rust-lang/rust/issues/16507 discussion

– Stoogy
Nov 22 '18 at 12:05

@Stoogy thanks; I've commented on the issue.

– Petrus Theron
Nov 22 '18 at 17:28

add a comment |

I don't understand how Rust concatenates file paths. Why doesn't this work:

fn main() {

    let root = std::path::Path::new("resources/");

    let uri = std::path::Path::new("/js/main.js");

    let path = root.join(uri);

    assert_eq!(path.to_str(), Some("resources/js/main.js"));

}

fails with:

thread 'main' panicked at 'assertion failed: `(left == right)`

  left: `Some("/js/main.js")`,

 right: `Some("resources/js/main.js")`', src/main.rs:5:5

I see in the docs that "pushing an absolute path replaces the existing path", but this seems like a terrible idea that will catch a lot of people.

In that case, how do I safely strip the absolute path, or make it relative?

edited Nov 22 '18 at 21:24

Shepmaster

163k16337483

asked Nov 22 '18 at 11:50

Petrus Theron

13.5k24114227

I don't understand how Rust concatenates file paths. Why doesn't this work:

fn main() {

    let root = std::path::Path::new("resources/");

    let uri = std::path::Path::new("/js/main.js");

    let path = root.join(uri);

    assert_eq!(path.to_str(), Some("resources/js/main.js"));

}

fails with:

thread 'main' panicked at 'assertion failed: `(left == right)`

  left: `Some("/js/main.js")`,

 right: `Some("resources/js/main.js")`', src/main.rs:5:5

I see in the docs that "pushing an absolute path replaces the existing path", but this seems like a terrible idea that will catch a lot of people.

In that case, how do I safely strip the absolute path, or make it relative?

rust filepath

edited Nov 22 '18 at 21:24

Shepmaster

163k16337483

asked Nov 22 '18 at 11:50

Petrus Theron

13.5k24114227

edited Nov 22 '18 at 21:24

Shepmaster

163k16337483

asked Nov 22 '18 at 11:50

Petrus Theron

13.5k24114227

edited Nov 22 '18 at 21:24

Shepmaster

163k16337483

edited Nov 22 '18 at 21:24

Shepmaster

163k16337483

edited Nov 22 '18 at 21:24

Shepmaster

163k16337483

asked Nov 22 '18 at 11:50

Petrus Theron

13.5k24114227

asked Nov 22 '18 at 11:50

Petrus Theron

13.5k24114227

asked Nov 22 '18 at 11:50

Petrus Theron

13.5k24114227

1

I guess you can see this: github.com/rust-lang/rust/issues/16507 discussion

– Stoogy
Nov 22 '18 at 12:05

@Stoogy thanks; I've commented on the issue.

– Petrus Theron
Nov 22 '18 at 17:28

add a comment |

1

I guess you can see this: github.com/rust-lang/rust/issues/16507 discussion

– Stoogy
Nov 22 '18 at 12:05

@Stoogy thanks; I've commented on the issue.

– Petrus Theron
Nov 22 '18 at 17:28

I guess you can see this: github.com/rust-lang/rust/issues/16507 discussion

– Stoogy
Nov 22 '18 at 12:05

@Stoogy thanks; I've commented on the issue.

– Petrus Theron
Nov 22 '18 at 17:28

add a comment |

1 Answer
1

active

oldest

votes

This is because "/js/main.js" is treated as an absolute path (doc)

If path is absolute, it replaces the current path.

On Windows:

if path has a root but no prefix (e.g. windows), it replaces everything except for the prefix (if any) of self.

if path has a prefix but no root, it replaces self.

If you change your example to "js/main.js" and then use join, it will be properly constructed (playground)

edited Nov 22 '18 at 12:08

answered Nov 22 '18 at 12:06

hellow

5,80252344

Thanks, then how do I treat the incoming path as always relative?

– Petrus Theron
Nov 22 '18 at 12:07

FYI: os.path.join has the same behavior in Python. I am not sure why, but at least there's some consistency there.

– Matthieu M.
Nov 22 '18 at 12:08

1

@PetrusTheron I would suggest not using / at all. You can omit them completly.

– hellow
Nov 22 '18 at 12:11

2

@TimDiekmann quoting the doc: "The difference between absolutize and canonicalize methods is that absolutize does not care about whether the file exists and what the file really is." ;)

– hellow
Nov 22 '18 at 12:16

1

@PetrusTheron you can use Path::strip_prefix to remove the leading /: playground

– Jmb
Nov 22 '18 at 15:54

|
show 4 more comments

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1 Answer
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active

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1 Answer
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votes

This is because "/js/main.js" is treated as an absolute path (doc)

If path is absolute, it replaces the current path.

On Windows:

if path has a root but no prefix (e.g. windows), it replaces everything except for the prefix (if any) of self.

if path has a prefix but no root, it replaces self.

If you change your example to "js/main.js" and then use join, it will be properly constructed (playground)

edited Nov 22 '18 at 12:08

answered Nov 22 '18 at 12:06

hellow

5,80252344

Thanks, then how do I treat the incoming path as always relative?

– Petrus Theron
Nov 22 '18 at 12:07

FYI: os.path.join has the same behavior in Python. I am not sure why, but at least there's some consistency there.

– Matthieu M.
Nov 22 '18 at 12:08

1

@PetrusTheron I would suggest not using / at all. You can omit them completly.

– hellow
Nov 22 '18 at 12:11

2

@TimDiekmann quoting the doc: "The difference between absolutize and canonicalize methods is that absolutize does not care about whether the file exists and what the file really is." ;)

– hellow
Nov 22 '18 at 12:16

1

@PetrusTheron you can use Path::strip_prefix to remove the leading /: playground

– Jmb
Nov 22 '18 at 15:54

|
show 4 more comments

This is because "/js/main.js" is treated as an absolute path (doc)

If path is absolute, it replaces the current path.

On Windows:

if path has a root but no prefix (e.g. windows), it replaces everything except for the prefix (if any) of self.

if path has a prefix but no root, it replaces self.

If you change your example to "js/main.js" and then use join, it will be properly constructed (playground)

edited Nov 22 '18 at 12:08

answered Nov 22 '18 at 12:06

hellow

5,80252344

Thanks, then how do I treat the incoming path as always relative?

– Petrus Theron
Nov 22 '18 at 12:07

FYI: os.path.join has the same behavior in Python. I am not sure why, but at least there's some consistency there.

– Matthieu M.
Nov 22 '18 at 12:08

1

@PetrusTheron I would suggest not using / at all. You can omit them completly.

– hellow
Nov 22 '18 at 12:11

2

@TimDiekmann quoting the doc: "The difference between absolutize and canonicalize methods is that absolutize does not care about whether the file exists and what the file really is." ;)

– hellow
Nov 22 '18 at 12:16

1

@PetrusTheron you can use Path::strip_prefix to remove the leading /: playground

– Jmb
Nov 22 '18 at 15:54

|
show 4 more comments

This is because "/js/main.js" is treated as an absolute path (doc)

If path is absolute, it replaces the current path.

On Windows:

if path has a root but no prefix (e.g. windows), it replaces everything except for the prefix (if any) of self.

if path has a prefix but no root, it replaces self.

If you change your example to "js/main.js" and then use join, it will be properly constructed (playground)

edited Nov 22 '18 at 12:08

answered Nov 22 '18 at 12:06

hellow

5,80252344

This is because "/js/main.js" is treated as an absolute path (doc)

If path is absolute, it replaces the current path.

On Windows:

if path has a root but no prefix (e.g. windows), it replaces everything except for the prefix (if any) of self.

if path has a prefix but no root, it replaces self.

If you change your example to "js/main.js" and then use join, it will be properly constructed (playground)

edited Nov 22 '18 at 12:08

answered Nov 22 '18 at 12:06

hellow

5,80252344

edited Nov 22 '18 at 12:08

answered Nov 22 '18 at 12:06

hellow

5,80252344

answered Nov 22 '18 at 12:06

hellow

5,80252344

answered Nov 22 '18 at 12:06

hellow

5,80252344

Thanks, then how do I treat the incoming path as always relative?

– Petrus Theron
Nov 22 '18 at 12:07

FYI: os.path.join has the same behavior in Python. I am not sure why, but at least there's some consistency there.

– Matthieu M.
Nov 22 '18 at 12:08

1

@PetrusTheron I would suggest not using / at all. You can omit them completly.

– hellow
Nov 22 '18 at 12:11

2

@TimDiekmann quoting the doc: "The difference between absolutize and canonicalize methods is that absolutize does not care about whether the file exists and what the file really is." ;)

– hellow
Nov 22 '18 at 12:16

1

@PetrusTheron you can use Path::strip_prefix to remove the leading /: playground

– Jmb
Nov 22 '18 at 15:54

|
show 4 more comments

Thanks, then how do I treat the incoming path as always relative?

– Petrus Theron
Nov 22 '18 at 12:07

FYI: os.path.join has the same behavior in Python. I am not sure why, but at least there's some consistency there.

– Matthieu M.
Nov 22 '18 at 12:08

1

@PetrusTheron I would suggest not using / at all. You can omit them completly.

– hellow
Nov 22 '18 at 12:11

2

@TimDiekmann quoting the doc: "The difference between absolutize and canonicalize methods is that absolutize does not care about whether the file exists and what the file really is." ;)

– hellow
Nov 22 '18 at 12:16

1

@PetrusTheron you can use Path::strip_prefix to remove the leading /: playground

– Jmb
Nov 22 '18 at 15:54

Thanks, then how do I treat the incoming path as always relative?

– Petrus Theron
Nov 22 '18 at 12:07

FYI: os.path.join has the same behavior in Python. I am not sure why, but at least there's some consistency there.

– Matthieu M.
Nov 22 '18 at 12:08

@PetrusTheron I would suggest not using / at all. You can omit them completly.

– hellow
Nov 22 '18 at 12:11

@TimDiekmann quoting the doc: "The difference between absolutize and canonicalize methods is that absolutize does not care about whether the file exists and what the file really is." ;)

– hellow
Nov 22 '18 at 12:16

@PetrusTheron you can use Path::strip_prefix to remove the leading /: playground

– Jmb
Nov 22 '18 at 15:54

|
show 4 more comments

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