How to use listings inside pgfplots captions?

Question

I need to add a (general) listings code in a plot caption. For some reason listings (inline) doesn't interact well with \addlegendentry, what can I do to make the same code work outside and inside an \addlegendentry environment?

Note that it even gives an strange result (see image), where the phrase is in the wrong order.

\documentclass[]{article}
\usepackage{pgfplots}
\usepackage[]{listings}
\begin{document}
\lstinline[]|(double x){bbbb}| %ok

\begin{tikzpicture}
\begin{axis}[]
\addlegendentry{\lstinline[]|(double x){bbbb;}|}; %not ok, garbage
\addplot+[mark=none, line join=round, fill opacity = 0.5, ] coordinates {
( 1, 2 )
( 3, 4)
}; 
\end{axis}
\end{tikzpicture}
\end{document}

One workaround I found is to put \{...\} in the \legendentry case, but doing so doesn't do the same thing outside the pgfplot and I want to use the same code regardless if possible. Maybe the solution is an option that I have to pass to the tikzpicture environment, or to the tikz package or to the listing.

(These verb-like environments always give me headaches.)

---

EDIT: Thanks to Gonzalo's clarification, I made this code that allows to use the same code inside and outside the caption, it uses a hack (\textrm, other solutions are welcomed):

\documentclass[]{article}
\usepackage{pgfplots}
\usepackage[]{listings}
\begin{document}
\textrm{\lstinline[]|(double x)\{bbbb\}|} %ok
\begin{tikzpicture}
\begin{axis}[small]
\addlegendentry{\textrm{\lstinline[]|(double x)\{bbbb\}|}}; %now ok
\addplot+[mark=none, line join=round, fill opacity = 0.5, ] coordinates {( 1, 2 )}; 
\addlegendentry{\lstinline[]|(double x){bbbb;}|}; % not ok, garbage
\addplot+[mark=none, line join=round, fill opacity = 0.5, ] coordinates {( 1, 2 )}; 
\addlegendentry{\lstinline[]|(double x)\{bbbb\}|}; % not what one expects
\addplot+[mark=none, line join=round, fill opacity = 0.5, ] coordinates {( 1, 2 )}; 
\end{axis}
\end{tikzpicture}
\end{document}

Answer 1

The use of \lstinline inside arguments is experimental; see this subsection in the documentation:

5.1 Listings inside arguments

There are some things to consider if you want to use \lstinline or the listing environment inside arguments. Since TeX reads the argument before the "lst- macro" is executed, this package can’t do anything to preserve the input: spaces shrink to one space, the tabulator and the end of line are converted to spaces, TeX's comment character is not printable, and so on. Hence, you must work a bit more. You have to put a backslash in front of each of the following four characters: \{}%. Moreover you must protect spaces in the same manner if: (i) there are two or more spaces following each other or (ii) the space is the first character in the line. That’s not enough: Each line must be terminated with a "line feed" ^^J. And you can’t escape to LaTeX inside such listings!

I am afraid the only solution is then, as suggested in the documentation, to use \{ and \}:

\documentclass[]{article}
\usepackage{pgfplots}
\usepackage[]{listings}

\begin{document}

\begin{tikzpicture}
\begin{axis}[]
\addlegendentry{\lstinline[]|(double x)\{bbbb;\}|}; 
\addplot+[mark=none, line join=round, fill opacity = 0.5, ] coordinates {
( 1, 2 )
( 3, 4)
}; 
\end{axis}
\end{tikzpicture}

\end{document}

An alternative would be to use the listings interface to fancyvrb (or to use fancyvrb directly):

\documentclass[]{article}
\usepackage{pgfplots}
\usepackage{fancyvrb}

\fvset{commandchars=\\\{\}}

\begin{document}
\Verb!(double x)\{bbbb;\}!

\begin{tikzpicture}
\begin{axis}[]
\addlegendentry{\Verb!(double x)\{bbbb;\}!}; 
\addplot+[mark=none, line join=round, fill opacity = 0.5, ] coordinates {
( 1, 2 )
( 3, 4)
}; 
\end{axis}
\end{tikzpicture}

\end{document}