[jira] [Commented] (CLI-249) Message for an illegal character in an option should contain more information

["David Goodenough (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CLI-249?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14525124#comment-14525124 ] 

David Goodenough commented on CLI-249:
--------------------------------------

I am not sure I am the best person to do this.  I am a user of code that uses this code.  You really need input from those that write that latter code.

However if I were doing it I would look at one of two mechanisms.  Either I would add a parameter which is a simple string and would add it to the end of the message, so the caller could might pass in the whole string that is being parsed if it is a command line parse, or a file name and line number if it is a file parse.  Both of these would give context to the error message.

As an alternative if you are able to require Java 8(+) then you could pass in a lambda which would get called to return this extra string - that way if we are thinking performance the error string is only created when needed. 

> Message for an illegal character in an option should contain more information
> -----------------------------------------------------------------------------
>
>                 Key: CLI-249
>                 URL: https://issues.apache.org/jira/browse/CLI-249
>             Project: Commons CLI
>          Issue Type: Improvement
>          Components: CLI-1.x
>            Reporter: David Goodenough
>             Fix For: 1.3
>
>
> Currently the code in org.apache.commons.cli.OptionValidator generates an IllegalArgumentException which contains the message:-
> "illegal option value '" + ch + "'"
> This is generated in two places, one for single character options and one for multi character options.
> However this does not tell the caller which option it is contains this 
> character, which makes debugging the error without the source (i.e most users) extremely difficult.
> Would it not be possible to change the message to:-
> "illegal option '" + opt + "' value '" + ch + "'"
> which would then at least identify the offending option.



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