[debug] tracing \pretocmd on input line 10
[debug] analyzing '\begin'
[debug] ++ control sequence is defined
[debug] ++ control sequence is a macro
[debug] ++ control sequence is a macro with parameters
[debug] -- macro cannot be retokenized cleanly
[debug] -> the macro may have been defined under a category
[debug]    code regime different from the current one
[debug] -> the replacement text may contain special control
[debug]    sequence tokens formed with \csname...\endcsname;
[debug] -> the replacement text may contain carriage return,

\NewDocumentCommand \Surroundwithxframed { O{} m }
 {
   \xframed_before_env:n { #2 } { \begin{xframed}[#1] }
   \xframed_after_env:n  { #2 } { \end{xframed}       }
 }

%%use the command only if exists
\cs_new:Npn  \xframed_csuse_withouterrors:n #1
 {
  \cs_if_exist:cT { #1 }
    { \use_c { #1 } }
 }

%%puts material before the environment
%%  \xframed_before_env:n{env-name}{material}
\cs_new:Npn \xframed_before_env:n #1
 {
  \tl_gput_left:cn {xframed_beforebegin_#1_hook}
 }
%%puts material after the environment

\documentclass{article}
\usepackage{regexpatch}

\makeatletter
\regexpatchcmd{\begin}
  {\A}
  {\c{xframed_csuse_withouterrors:n}  { xframed_beforebegin_\cP\#1_hook } }
  {}{}
\makeatother
\show\begin

\makeatletter
\regexpatchcmd{\begin}
  {\A}
  {\c{xframed_csuse_withouterrors:n}  \cB\{ xframed_beforebegin_\cP\#1_hook \cE\} }
  {}{}
\makeatother

\xpatchcmd
 { \end }
 {\if@ignore}
 {
  \xframed_csuse_withouterrors:n  { xframed_afterend_#1_hook }
  \if@ignore
 }
 {
  \msg_info:nnn {xframed} { patching-worked } { \end }
 }
 {
  \msg_warning:nnn {xframed} { patching-failed } { \end }
 }

\makeatletter
\regexpatchcmd{\begin}
  {\A}
  {\c{xframed_csuse_withouterrors:n}  \cB\{ xframed_beforebegin_\cP\#1_hook \cE\} }
  {}{}
\regexpatchcmd{\end}
 {\c{if@ignore}}
 {\c{xframed_csuse_withouterrors:n}  \cB\{ xframed_afterend_\cP\#1_hook \cE\}
  \c{if@ignore}}
 {}{}
\show\begin
\show\end

\makeatother

\documentclass{article}
\usepackage{xparse,regexpatch,framed}
\ExplSyntaxOn
\NewDocumentCommand \Surroundwithxframed { O{} m }
 {
   \xframed_before_env:nn { #2 } { \begin{framed} }
   \xframed_after_env:nn  { #2 } { \end{framed}      }
 }
%%use the command only if exists
\cs_new:Npn  \xframed_csuse_withouterrors:n #1
 {
  \cs_if_exist:cT { #1 }
    { \use:c { #1 } }
 }

%%puts material before the environment
%%  \xframed_before_env:n{env-name}{material}
 \cs_new:Npn \xframed_before_env:nn #1 #2

\tl_gput_left:cn { l_eg_tl } {xxx}
\tl_show:c {l_eg_tl}

> \l_eg_tl=macro:
->xxx\l_eg_tl .

%%puts material before the environment
%%  \xframed_before_env:n{env-name}{material}
\cs_new:Npn \xframed_before_env:nn #1 #2
 {
  \tl_if_exist:cF { xframed_beforebegin_#1_hook }
   { \tl_new:c { xframed_beforebegin_#1_hook } }
  \tl_gput_left:cn {xframed_beforebegin_#1_hook}{ #2 }
 }
%%puts material after the environment
%%  \xframed_after_env:n{env-name}{material}
\cs_new:Npn \xframed_after_env:nn #1 #2
 {
  \tl_if_exist:cF { xframed_afterend_#1_hook }
   { \tl_new:c { xframed_afterend_#1_hook } }