显示/重定义内部宏

Posted 2021-02-26

These four LaTeX control sequences are workalikes of the built-ins show, showthe and def and of a command sequence call. Unlike the usual variants, they work on internal macros which contain characters with the "wrong" category code, such as "@". They take the name of the command sequence (without the leading "") as their argument.

The scrollmode is not necessary, it just saves you pressing Return for every listing output. The obeyspaces is needed only if you want to display or manipulate control sequences whose names contain spaces.

Gratuitous use of don and/or defn will probably break LaTeX.

scrollmode
 
obeyspaces
 
defshown#1{expandaftershowcsnamestring#1endcsname}
defshowthen#1{expandaftershowthecsnamestring#1endcsname}
defdon#1{csnamestring#1endcsname}
defdefn#1{expandafterdefcsnamestring#1endcsname}
 
% example usage:
 
% show listing of [email protected]
shown{@startsection}
 
% show the value of the skip @tempskipa
showthen{@tempskipa}
 
% execute control sequence "\ "
don{ }
 
% redefine @startsection (works like def)
defn{@startsection}{
elax}
 
% use at your own risk.  user forfeits all rights to data integrity, mental health, world order, cookies.