Support `str(datamodule)`

[carmocca]

🚀 Feature

Add support

print(str(MyDataModule()))

Motivation

It currently prints:

<__main__.MyDataModule object at 0x10284c970>

Pitch

It could print the DataLoader structure:

MyDataModule(
    train_dataloader: {"a": DataLoaderClass(batch_size=8, num_batches=16, num_workers=2), "b":  DataLoaderClass(batch_size=2, num_batches=16, num_workers=2)]
    val_dataloader: [DataLoaderClass(batch_size=3, num_batches=14, num_workers=0), DataLoaderClass(batch_size=8, num_batches=4, num_workers=0)]
    test_dataloader: DataLoaderClass(batch_size=4, num_batches=7, num_workers=2)
)

Or the number of batches per dataloader, similar to what was done in #5965

Alternatives

Open to other ideas

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[carmocca]

cc @kingyiusuen

[Abelarm]

I could take care of this 👍

[kingyiusuen]

cc @kingyiusuen

I am happy to let @Abelarm take it :)

[Abelarm]

Hi guys I am currently at a problem between:

and

*

*which is not consistent on the prints.

the problem is the str() of the dict :(

Do you have any idea? or one of the two solutions is good enough?

[Abelarm]

Hi guys I am currently at a problem between:

and

*

*which is not consistent on the prints.

the problem is the str() of the dict :(

Do you have any idea? or one of the two solutions is good enough?

if you really want the keys of the dict to be with "" I can do it but it won't be the nicest of the solutions

[carmocca]

Hey @Abelarm! You can open a draft PR so we can check your current implementation and discuss it.

[dmarx]

in the spirit of https://docs.python.org/3.4/reference/datamodel.html#object.__repr__

If at all possible, this should look like a valid Python expression that could be used to recreate an object with the same value (given an appropriate environment).

I recommend:

1. keeping the quotes around dict keys but not dict values
2. using an = after the name of initialization parameters instead of a :

Following these recommendations, @Abelarm 's test expression would become:

MyDataModule(
    train_dataloader={"a": DataLoaderClass(batch_size=8, num_batches=16, num_workers=2), "b":  DataLoaderClass(batch_size=2, num_batches=16, num_workers=2)]
    val_dataloader=[DataLoaderClass(batch_size=3, num_batches=14, num_workers=0), DataLoaderClass(batch_size=8, num_batches=4, num_workers=0)]
    test_dataloader=DataLoaderClass(batch_size=4, num_batches=7, num_workers=2)
)

[tchaton]

Hey @carmocca,

I believe adding support for str() provides the same inconvenient as using len().

It might be worth to consider a describe LightningDataModule method instead.

Best,
T.C