Allow redirecting to stdout

[Achille Lacoin]

By default, pandocotomatic does not redirect the output to stdout but to stdout like pandoc.

It make it harder to implement a chaining of command.

[Huub de Beer]

True. In the past I have though about adding stdin/out, but always decided against it because I had no clear use-case for it. Can you give me one or more real-world use-cases with examples of when, how, and why you would like to use stdin/out with pandocomatic?

Furthermore, because I have never taken into account input from stdin/out, the current implementation of pandocomatic assumes input and output files all over the place. That means that just bolting it on somehow is not a good idea. However, moving forward to the next major version, I could redesign pandocomatic to support stdin/out.

[Achille Lacoin]

My school use an webinterface for the documentation of student's project. It uses an exotic format, dokuwiki.
In order to use markdown, and the advantages of my editor, i usually run pandoc -t dokuwiki input.md | pbcopy, and i paste the content of my clipboard into the web interface.

[Huub de Beer]

And you would like to be able to run pandocomatic input.md | pbcopy?

I tried to automatically copy the results of a pandocomatic conversion to the clipboard with the xclip command-line utility in a postprocessor:

• copy.sh in PATH:

  #!/usr/bin/env bash
  xclip <&0
  

• copy-to-clipboard template in my pandocomatic configuration file:

  templates:
    copy-to-clipboard:
      pandoc:
        from: markdown
        to: dokuwiki
      postprocessors:
      - copy.sh 
  

• a test.md file that uses that template:

  ---
  pandocomatic_:
    use-template: copy-to-clipboard
  ...
  
  Hello World! This whole document is converted to *dokuwiki* and copied to the
  clipboard!
  

Unfortunately, if I try to run this via pandocomatic -c my-config.yaml -i test.md pandocomatic does not quit. I have to press control+D to quit the pandocomatic process. On the other hand, the contents of the conversion are being copied to the clipboard.

I am not sure why pandocomatic does not quit when using the copy.sh postprocessor script, but this might be an interesting avenue for you to explore further.

[Achille Lacoin]

I also think it's doable with a postprocessor, but it would be a nice to have a toml setting to toggle it :)

In asciidoctor, also in ruby, you can toggle this behavior by using the asciidoctor -o - test.adoc, and pandoc does it by default

[Huub de Beer]

I've marked this issue as a "should have" requirement for the next major version of pandocomatic. If you have any other use cases for stdin / stdout or other comments, please feel free to add to this issue.

(Note. As of yet I do not know when I will be working on the next major version, so it can take quite a long while before this will be implemented)

[TJ Kolleh]

Another usecase for chaining commands using stdin / stdout is for apps like Marked 2. The app can use a custom processors to generate styled html. It uses stdin/out for auto loading. I've been thinking of ways to wrap pandocomatic or use its pre/post processors to handle this usecase. Any advice on a how to achieve stdin/out using a wrapper?

[Huub de Beer]

Creating a wrapper is fairly straightforward. You can have a look at my Processor class, which is a wrapper for preprocessor / postprocessor scripts. It uses the Open3 module from the standard library for handling and running external processes with STDIN and STDOUT.

[Huub de Beer]

Finished implementing output to STDOUT. I've added a new command line option, --stdout, to print the result of pandocomatic on standard output. This command line option does not work together with --output, nor with converting whole directories. It'll be available in pandocomatic 0.3 that's coming in the next months.