document how to model a one-or-the-other parameter

[mr-c]

From https://groups.google.com/d/msg/common-workflow-language/t7GEjKwJHys/2BvtkhsjXxMJ

> I'm not seeing how to model a boolean so that both 'true' and 'false' result
> in differents strings being added to the command line.

One way to do this is to define an "enum" where the symbols are the
two alternate command line flags.  Another way is to use an expression
that overrides the default handling of boolean.  A third way would be
to define two types with the command line flag in inputBinding.prefix
and use a union.

[mr-c]

Moved from https://github.com/common-workflow-language/common-workflow-language/issues/68

[mr-c]

expression example:

cwlVersion: v1.0
class: CommandLineTool
requirements:
  InlineJavascriptRequirement: {}
inputs:
  fancy_bool:
     type: boolean
     default: false  # or true
     inputBinding:
        valueFrom: ${if (self) { return "foo";} else { return "bar";}}

baseCommand: echo

outputs: []

[mr-c]

enum example

cwlVersion: v1.0
class: CommandLineTool
inputs:
  one_or_the_other:
     type:
       type: enum
       symbols: [ foo, bar ]

baseCommand: echo
outputs: []

[mr-c]

way "1" and "3" still need adding to the docs

[tobyhodges]

I don’t think it’s necessary to document three different ways to do it. If there’s one approach that you prefer or that you think is most accessible to beginners/non-experts, I think we should include that one only.

On Sat, 27 Jul 2019 at 17:19, Michael R. Crusoe [email protected] wrote:

way "1" and "3" still need adding to the docs

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