In a book (Clean Architecture, Robert C. Martin, page 46) I read
(e.g., jar files, DLLs, or Gem files)
I wonder about the use of commas and or. I would have expected
(e.g. jar files, DLLs or Gem files)
Are the two additional commas wrong, irrelevant or do they provide additional meaning here?
From The Cambridge Guide to English Usage (Peters, 2004):
The punctuation before and after e.g. has long been the subject of prescription. A comma used to be considered necessary after it, and is still usual, according to the Chicago Manual (2003). But most style guides now dispense with the following comma, and simply emphasize having one before it. Other punctuation marks, such as a dash, colon or opening parenthesis could equally well come before it, depending on the structure of the sentence.
Punctuation with or. This is simply a matter of whether to put a comma before or when it introduces the last of a series of alternatives. The issue is the same as for and in the same position. See the discussion of the serial comma.
