Use information from label when formatting an entry text

[Massimo D'Antoni]

I am trying to create a formatting style to be used with natbib.sty, which relies on labels with author and year. A difficulty I found is that, in case two references have the same label, the solution with author-year citations is to add a letter to the year (e.g. 2018a, 2018b), and this letter should appear both in the label and in the text of the entry. However, I noticed that the label modifiers are introduced by the function format_entries, while the text of each entry is formatted in format_entry (both functions are defined in style/formatting/__init__.py). In order for format_entry to be aware that the year has been modified by format_entries, I suggest that in the definition of context in format_entry a 'label' key is added:

    def format_entry(self, label, entry, bib_data=None):
            context = {
                'entry': entry,
                'style': self,
                'label': label,               # <----------
                'bib_data': bib_data,
            }

In this way, the modified year in the label can be used to format the year of the text. Maybe there are better solutions, but this solved my problem.