Enhance OptionParser.ParseError with available options display #14673
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Example output:
Expected one of:
--count INTEGER (alias: -c)
--debug, --no-debug (alias: -d)
--files STRING (alias: -f) (may be given more than once)
--verbose, --no-verbose (alias: -v)
Prompt
======
When we raise ParseError, include all of the options we could
potentially accept, alongside their types and aliases. For example,
the switches `[foo: :string, bar: :integer]` and `aliases: [b: :bar]`,
the error message should say:
Expected one of:
--foo STRING
--bar INTEGER (alias: -b)
Furthermore, for types that are :keep (which default to string), you should
add:
--bar INTEGER (alias: -b) (may be given more than once)
And boolean ones accept no arguments, so they should be written as:
--baz, --no-baz
Sort all of them alphabetically.
josevalim
commented
Jul 26, 2025
| @@ -282,11 +282,11 @@ defmodule OptionParser do | |||
|
|
|||
| iex> OptionParser.parse!(["--limit", "xyz"], strict: [limit: :integer]) | |||
| ** (OptionParser.ParseError) 1 error found! | |||
| --limit : Expected type integer, got "xyz" | |||
| --limit : Expected type integer, got "xyz"... | |||
There was a problem hiding this comment.
I had to add those manually.
There was a problem hiding this comment.
Should it really be printed in this case, though? I feel like it makes a lot of sense to print all the options when you use a unknown option, but when you use the wrong type, isn't it mostly noise?
There was a problem hiding this comment.
Agreed, it's probably more tokens for the LLM to consume too 😄 However, sometimes you might be doing --limit $ENV_VAR and it could be useful to see what the env var was expanded as
There was a problem hiding this comment.
I think it should because the wrong type can also be an indicator that you are calling the wrong option, especially when aliases are involved. For example, you can pass -n with a name, thinking it is about --name, but it is actually a number.
zachdaniel
approved these changes
Jul 26, 2025
rmand97
reviewed
Jul 26, 2025
Co-authored-by: rmand97 <[email protected]>
|
💚 💙 💜 💛 ❤️ |
josevalim
added a commit
that referenced
this pull request
Jul 26, 2025
Example output:
Expected one of:
--count INTEGER (alias: -c)
--debug, --no-debug (alias: -d)
--files STRING (alias: -f) (may be given more than once)
--verbose, --no-verbose (alias: -v)
Prompt
======
When we raise ParseError, include all of the options we could
potentially accept, alongside their types and aliases. For example,
the switches `[foo: :string, bar: :integer]` and `aliases: [b: :bar]`,
the error message should say:
Expected one of:
--foo STRING
--bar INTEGER (alias: -b)
Furthermore, for types that are :keep (which default to string), you should
add:
--bar INTEGER (alias: -b) (may be given more than once)
And boolean ones accept no arguments, so they should be written as:
--baz, --no-baz
Sort all of them alphabetically.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Example output:
Prompt
When we raise ParseError, include all of the options we could potentially accept, alongside their types and aliases. For example, the switches
[foo: :string, bar: :integer]andaliases: [b: :bar], the error message should say:Furthermore, for types that are :keep (which default to string), you should add:
And boolean ones accept no arguments, so they should be written as:
Sort all of them alphabetically.