BurntSushi/walkdir

[feature] Create a `try_filter_entry()`

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#131 opened on Nov 11, 2019

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enhancementhelp wanted

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Description

I am using this library and have run into the need to capture a potential error inside of the filter_entry predicate. I asked in a forum topic about my problem and the response was that the best way to accomplish it would be with a try_filter_entry iterator so that I could return a result inside of the filter predicate.

I did a quick check of the source code to see how I might be able to implement that, but I was wondering if you might have any guidance on how you would want that implemented.

I haven't ever written an iterator before, but it looks like, if I wanted to create a FilterEntry iterator that it would be nearly identical to the existing TryFilterEntry iterator, but not quite the same.

Is there any way to share most of the implementation without duplicating code, or is it better just to create a copy of FilterEntry and the make the changes necessary.

Contributor guide

Research direction
Study the existing `FilterEntry` iterator implementation in `walkdir/src/lib.rs`. Understand how it implements the `Iterator` trait and how it wraps directory entries. Then create a `TryFilterEntry` struct similar to `FilterEntry` but with a predicate that returns `Result<bool, E>`. Implement the `Iterator` trait for `TryFilterEntry` using a `try for each` like pattern to propagate errors. Look at how other Rust libraries like `std::iter::FilterMap` handle fallible closures.
Tech stack
rust
Domain
backend
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Rust
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65