How to use a variable number of arguments in pyinvoke

As of version 0.21.0 you can use iterable flag values:

@task(
  help={
      'out-file': 'Name of the output file.', # `out-file` NOT `out_file`
      'in-files': 'List of the input files.'},
  iterable=['in_files'],
)
def pdf_combine(out_file, in_files):
    for item in in_files:
        print(f"file: {item}")

NOTE help using the dash converted key and iterable using the non-converted underscore key

NOTE I understand the above note is kinda odd, so I submitted a PR since the author is pretty awesome and might take the suggestion into consideration

Using it in this way allows for this type of cli:

$ invoke pdf-combine -o spam -i eggs -i ham
  file: eggs
  file: ham

$ invoke --help pdf-combine
Usage: inv[oke] [--core-opts] pdf-combine [--options] [other tasks here ...]

Docstring:
  none

Options:
  -i, --in-files                 List of the input files
  -o STRING, --out-file=STRING   Name of the output file.

NOTE pdf_combine task is called with inv pdf-combine from the CLI

You can do something like this:

from invoke import task

@task
def pdf_combine(out_file, in_files):
    print( "out = %s" % out_file)
    print( "in = %s" % in_files)
    in_file_list = in_files.split(',')   # insert as many args as you want separated by comma

>> out = binder.pdf
>> in = test.pdf,test1.pdf,test2.pdf

Where the invoke command is:

invoke pdf_combine -o binder.pdf -i test.pdf,test1.pdf,test2.pdf

I couldn't find another way to do this reading the pyinvoke documentation.