Implicit Conversion of Optional Flags

[Radagaisus]

It’s fairly common to use flags both to check whether a given action should be done and use the flag values as data for the action. The implicit type conversion in ArgparsePrompt messes with this pattern. For example:

parser.add_argument('--population_snapshot', type=str, default=None)

Using this definition and using the default value in the prompt will convert None to 'None'.

parser.add_argument('--seed', type=int, default=None)

The same happens here, only this time an exception will be thrown (Argument "seed" was given a value not of type <class 'int'>).

[multimeric]

Thanks for this report. I'll try to follow what argparse does here, but I suspect it doesn't apply the type function to the default argument, which is the behaviour you also want.

In the meantime you can use a custom function that accepts either, e.g. type=lambda x: x is None ? None else int(x).

[multimeric]

This should now be fixed in 0.0.5, and it's included as a test now. I've also published a new release on PyPI. The new behaviour is designed to mirror what argparse does:

If the default value is a string, the parser parses the value as if it were a command-line argument. In particular, the parser applies any type conversion argument, if provided, before setting the attribute on the Namespace return value. Otherwise, the parser uses the value as is

[Radagaisus]

Looks good. Thanks!

[Radagaisus]

With the new changes, default=None will not appear in the prompt.

seed: Seed for fixed random number generation
> 
population_size: Maximum number of agents in each generation
> (100) 

Probably better if it’s visible:

seed: Seed for fixed random number generation
> (None)

[multimeric]

Hmm, yes it's a bit unhelpful that I convert None to an empty string. I'll fix this eventually, but PRs welcome (with a test).

[multimeric]

Fixed in 0.0.6.