Programmatic API guide for picocli 4.1 (#885)

[deining]

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[codecov-io]

Codecov Report

Merging #889 into master will not change coverage.
The diff coverage is n/a.

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  Coverage     92.84%   92.84%           
  Complexity      388      388           
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  Files             2        2           
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  Branches       1512     1512           
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  Hits           5396     5396           
  Misses          205      205           
  Partials        211      211

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[remkop]

Merged. Thank you!

I will probably replace the old 3.0-programmatic-api document with a link to the latest one.

[remkop]

Thanks a lot for the PR! Awesome work!

I changed it a bit to use lambdas which is nice and concise.

I renamed the file to remove the version number and redirect the old https://picocli.info/picocli-3.0-programmatic-api.html to the new doc.
That should make maintenance easier in the future.

I also shortened the first example and expanded the example in the Execute section (near the end).

Let me know what you think.

[deining]

I changed it a bit to use lambdas which is nice and concise.
I also shortened the first example and expanded the example in the Execute section (near the end).

Great improvements, thanks for reviewing my PR.
Glad to see the document updated now.

One small glitch I came across:

The usage help message of the first example states:

Usage: <main class> [-hV] [-c=COUNT] FILES...
      FILES...        The files to process
  -c, --count=COUNT   number of times to execute
  -h, --help          Show this help message and exit.
  -V, --version       Print version information and exit.

If I run the command and specify --help as only argument, I'm getting no output (expected: help messaage).
If I run the command and specify --help foo as commad line arguments, I'm getting as output: 0 foo

Is this the intended behaviour?

[remkop]

@deining Good catch! That was a bug: our IExecutionHandler should also handle requests for help. Fixed now.