Changing example numbering with gb4e

Question

I want to change the default behavior of gb4e for a small portion of the text. I have a series of modifications of an example that I want to be labelled as if they were subexamples. For example:

(3a) Blah blah

But (3a) is problematic and can be refined:

(3b) Refined blah blah

The example gets "refined" about six times.

First MWE:

\documentclass{article}
\usepackage{gb4e}
\begin{document}
\begin{exe}
    \ex\label{ex:1} Blah
    \ex\label{ex:2} Blah
    \ex\label{ex:3a} Blah blah
\end{exe}

But (\ref{ex:3a}) is problematic and can be refined:
\begin{exe}
    \ex\label{ex:3b} Refined blah blah
\end{exe}

\end{document}

When I try to just override the label using gb4e's \exi command, the cross-referencing gets messed up:

\documentclass{article}
\usepackage{gb4e}
\begin{document}
\begin{exe}
\ex\label{ex:1} Blah
\ex\label{ex:2} Blah
\exi{(3a)}\label{ex:3a} Blah blah
\end{exe}

But (\ref{ex:3a}) is problematic and can be refined:
\begin{exe}
    \exi{(3b)}\label{ex:3b} Refined blah blah
\end{exe}
\setcounter{exx}{3}
\end{document}

Instead of printing "(3a)" it prints "(2)".

How do I achieve what I'm looking for in a way that respects the counters and gets cross-referencing right?

Answer 1

Here's one way to do this. I've defined an \exs macro that works just like top level \ex except that it adds an arabic subexample. When you are done with a series of subexamples you must use the \finsub to reset the counters for the next regular (or sub-) examples.

\documentclass{article}
\usepackage{gb4e}
\newcounter{mysub}
\makeatletter
\newcommand{\finsub}{\setcounter{mysub}{0}\stepcounter{exx}}
\newcommand{\exs}{\save@counters\refstepcounter{mysub}\renewcommand{\thexnumi}{\arabic{xnumi}\alph{mysub}}\@ifnextchar [{\@ex}{\item}\reset@counters}
\makeatother
\begin{document}

\begin{exe}
\ex Example 1 \label{ex:1}
\ex Example 2 \label{ex:2}
\exs Example 3a \label{ex:3a}
\end{exe}

But (\ref{ex:3a}) is problematic and can be refined:
\begin{exe}
    \exs Refined example 3a\label{ex:3b} 
\end{exe}

And if we think that (\ref{ex:3b}) is problematic we can redefine it again.

\begin{exe}
   \exs{Redefined example 3a yet again}
\label{ex:3c}
\end{exe}
\finsub

\begin{exe}
\ex{ This example won't be redefined  }
\label{ex:4}
\end{exe}

The next examples are also going to be redefined
\begin{exe}
\exs{ Example 5a }
\label{ex:5a}
\end{exe}

\begin{exe}
\exs{ Example 5b }
\label{ex:5b}
\end{exe}

\end{document}