Some, still Some, ...and then None?

help
1

Here, dir is an Option<FlexPath>, which is printed everytime as Some("/path/to/file").

println!("{dir:?}");
let workspace_or_main_dir = workspace_dir.as_ref().unwrap_or(dir.as_ref().unwrap());

// Target path
let target_path = PathBuf::from_str(&workspace_or_main_dir.resolve("target").to_string_with_flex_separator()).unwrap();

// Read the run cache file
let mut run_cache_file: Option<RunCacheFile> = None;
let run_cache_path = PathBuf::from_str(&workspace_or_main_dir.resolve("target/.run-cache.toml").to_string_with_flex_separator()).unwrap();
if std::fs::exists(&run_cache_path).unwrap() && std::fs::metadata(&run_cache_path).unwrap().is_file() {
    run_cache_file = Some(toml::from_str::<RunCacheFile>(&std::fs::read_to_string(&run_cache_path).unwrap()).unwrap());
}
if run_cache_file.is_none() {
    run_cache_file = Some(RunCacheFile {
        packages: vec![]
    });
}
let mut run_cache_file = run_cache_file.unwrap();

// Initial lockfile
if lockfile.is_none() {
    lockfile = Some(WhackLockfile {
        package: vec![]
    });
}
let mut lockfile = lockfile.unwrap();

// Current directory (prefer non-workspace directory)
println!("{dir:?}");
let dir = dir.as_ref().unwrap_or(workspace_dir.as_ref().unwrap());

However, in the last .unwrap() you see it simply panics. Why? It didn't panic the first time we used dir in the above code region (so it should be Some).

2

In the last line, you unwrap workspace_dir, not dir, and it was never unwrapped before. What's the question?

3

In the beginning:

println!("{dir:?}");
let workspace_or_main_dir = workspace_dir.as_ref().unwrap_or(dir.as_ref().unwrap());

In the ending lines:

println!("{dir:?}");
let dir = dir.as_ref().unwrap_or(workspace_dir.as_ref().unwrap());

What I mean is that workspace_dir is read as None, and dir is always read as Some. And it panicked because dir was wrongly assumed None, causing workspace_dir to evaluate.

4

No, in the last line: workspace_dir.unwrap() is evaluated before dir.unwrap_or().

Maybe, you would like unwrap_or_else()

let dir = dir.as_ref().unwrap_or_else(|| workspace_dir.as_ref().unwrap());

This effectively delays the evaluation of workspace.unwrap().

3 Likes
6

Wait, yes, I forgot that I was not lazily evaluating indeed. Thanks!

7

You could shorten that to

let dir = dir.as_ref().or(workspace_dir.as_ref()).unwrap();

3 Likes