How to break lines automatically when there are inline code format?

Question

My TeX have a lot of inline code to compile, so sometimes the output of PDF seems like this:

The outlined part is coded in {\tt set_task_state(current_state)}, How to automatically break the line within the set_task_state(current_stat)?

Answer 1

Line breaking for monotype font is a hard issue. Below, five options (really less since some of them produce results which are not acceptable); I'd suggest you to use the listings package instead of just \ttfamily (by the way, \tt is deprecated and shouldn't ne used anymore) to write your listings. I loaded showframe to have a visual guide of the text area.

\documentclass{article}
\usepackage{listings}
\usepackage{underscore}
\usepackage{showframe}

\lstset{
  basicstyle=\ttfamily\small,
  columns=fullflexible,
  breaklines=true
}

\begin{document}

The method {\ttfamily set_current_state(current_state)} is synonimous to {\ttfamily set_task_state(current_state)}

The method \lstinline|set_current_state(current_state)| is synonimous to \lstinline|set_task_state(current_state)|

{\sloppy
The method \lstinline|set_current_state(current_state)| is synonimous to \lstinline|set_task_state(current_state)|\par}

{\sloppy
The method {\ttfamily set_current_state(current_state)} is synonimous to {\ttfamily set_task_state(current_state)}\par}  

{\raggedright
The method \lstinline|set_current_state(current_state)| is synonimous to \lstinline|set_task_state(current_state)|\par}

{\raggedright
The method {\ttfamily set_current_state(current_state)} is synonimous to {\ttfamily set_task_state(current_state)}\par}

{{\ttfamily\hyphenchar\the\font=`\-}%
The method {\ttfamily set_current_state(current_state)} is synonimous to {\ttfamily set_task_state(current_state)}\par}

\end{document}

The result

Some comments

Using linebreaks=true enables line-break points; however, in this case, the verbatim text still protrudes.

Using sloppy leaves horrible big gaps between words.

Using \raggedright gives a somehow better and acceptable result here.

Answer 2

I recommend to combine two methods: to allow breakpoints at _ characters and to allow larger spaces if needed. The first method is realized by setting _ as active (using \tth instead \tt) and the second method needs to set the \emergencystretch register to the appropriate value:

{\catcode`\_=13 \gdef_{\string_\-}}
\def\tth{\tt\catcode`\_=13 }
\emergencystretch=3em

\hsize=14cm % for example

The method {\tth set_current_state(current_state)} is synonimous to
{\tth set_task_state(current_state)}.

\bye

You are probably using plain TeX (congratulations) because LaTeX users hate the \tt. So, my example is for plain TeX.