So,--exclude-file does not work and never worked as intended.

Note also that if it worked as intended, it would work differently than inxgettext. So why not implement thexgettext behavior?

So, --exclude-file does not work and never worked as intended.

Pretty much, yes. I randomly discovered this when writing the tests for it..

Note also that if it worked as intended, it would work differently than in xgettext. So why not implement the xgettext behavior?

If you're ok with that, I can implement it. The xgettext--exclude-file option reads the msgids from a PO file. Pygettext currently only knows how to write a PO file but not how to read it. msgfmt can read PO files so we could reuse the code from there. Perhaps create some helper file for PO reading/writing?

For now, I think that we can just copy the code frommsgfmt.py. In future we may add the code for reading the PO files in thegettext module.

Ok, I'll just copy it over then for now :)

In future we may add the code for reading the PO files in the gettext module.

That would actually be really helpful for my work as well. I'd be interested in contributing this. Have you already thought about how you'd like it to work? Should it be something compatible withGNUTranslations or do we want a richer interface that allows you to access e.g. the comments and flags as well?

For now, I think that we can just copy the code from msgfmt.py

Just to give an update, it probably won't be as simple. I started off by copying the code with minimal changes (just to get it to work with pygettext) and I discovered several bugs in the parsing logic when I started writing tests. I'll take some inspiration from the original code but I will need to make quite a few changes in order to make PO parsing work correctly.

I implement PO parsing in order to make--exclude-file work as it does inxgettext. I started with the code inmsgfmt.py but as I wrote before, there are some issues with it (e.g. bugs, differences from GNUmsgfmt) which I fixed and added lots of tests (actually most of this PR are tests now, so hopefully it won't be that daunting to review 😄 )

So to summarize:

• pygettext is now able to parse PO files. I also verified that the behaviour matches GNUmsgfmt (there's lots of edge cases, so I may have missed some though)
• --exclude-file now accepts a PO file. All msgids from this file are ignored when extracting.

@serhiy-storchaka Do you think you could have a look at this when you have time? 🙂

I think that it is better to fix the parser inmsgfmt first.

I think that it is better to fix the parser inmsgfmt first.

Originally, I was meaning to port this change to msgfmt after this is merged, but I can do the opposite. I'll send a PR to fix the msgfmt parser hopefully in a few days!