comma before and after 'and' [conjunction]: I was funny and, after

[hamptonz]

eg1: During our conversation you mentioned I was funny and, after having thought about it, I realized this to be true.
eg2: During our conversation you mentioned I was funny, and after having thought about it, I realized this to be true.


Are these both grammatically correct? Is one preferred over the other?

How do eg1 and eg2 differ from:

That explanation, as I have already said, doesn't really hold water.

 

[e2efour]

I prefer eg2 since it is only natural to have a slight pause after funny to show that it does not follow on from you mentioned.
There are really two sentences, each with its own subject (you and I). You can also write two sentences.

We often put a comma between two long phrases, especially if they express different ideas and they have different subjects.
The objection to eg1 is that when you first read it, you can easily think of you mentioned that I was funny and <another adjective or verb>.

In the last sentence as I have already said is a parenthetical phrase, and one way to make this clear is to set it off with commas.
[Note that in the last sentence I put a comma after phrase.]

 

[Beryl from Northallerton]

I think that both these commas have syntactic value, and for the reasons that e2efour gives. Therefore I think you need both.

eg3: During our conversation you mentioned I was funny, and, after having thought about it, I realized this to be true. (eg2 being far better than eg1).