Using a glob in generates property of a task

[adamurban98]

Hi there, let me briefly describe my problem:

If I opt for method: checksum it is enough for me to provide a sources property for a task to prevent it from rebuilding unnecessarily. However, I would still like to set the generates property in order to be able to detect manipulation with the generated files (e.g. the user deletes or moves one of them).

The trouble is, that one of my tasks is used to generate a folder with lots of images and this output is nondeterministic.

Desired behaviour

If I run task generate-images following files will be generated:

output_dir/img1.png
output_dir/img3.png
output_dir/img4.png
output_dir/img6.png
...

If the generates is set to output_dir or output_dir/* ,then it should remember the output folders checksum and if I run simply task generate-images again nothing should happen.
But if I force run it with task generate-images -f, or if change some file in the sources field, then the task should run again and a new set of images should be generated:

output_dir/img10.png
output_dir/img11.png
output_dir/img12.png
output_dir/img16.png
...

This behaviour already works if the generates property is set to be a list of specific files, while the sources property can contain globs as well. As I tried to explain above, however, in my case I cannot list a concrete list of files for the generates property as I don't know what those files will be.

Questions

1. Is it possible to solve this problem by somehow cleverly setting up the generates and sources attributes of the task?
2. Would you suggest to write a custom checking script? If yes, then how?
3. Can I somehow use the .CHECKSUM variable? What exactly is that variable? If i have multiple generates files, how can I programmatically calculate the same hash?

Thanks for any answers/suggestions in advance 🙂

[andreynering]

Hi @adamurban98,

1. It's not clear for me why setting generates to output_dir/**/* does not do what you want. From what I could understand it should.
2. Writing a script is a possibility, but if your code generation is not deterministic I'm afraid it won't be possible to solve this use case with this feature.
3. I don't think that .CHECKSUM will help with with this use case.

Sorry for not having more concrete answers for you. I think you should try to have a deterministic workflow, if possible.