How can texdef be made to return indented definitions?

Question

With texdef it is easy to find definitions for (La)TeX commands. It can show what a definition for a given command is. For instance if I issue texdef -t latex \LaTeX I get the following definitions:

\LaTeX:
macro:->\protect \LaTeX  


\LaTeX :
\long macro:->L\kern -.36em{\sbox \z@ T\vbox to\ht \z@ {\hbox {\check@mathfonts \fontsize \sf@size \z@ \math@fontsfalse \selectfont A}\vss }}\kern -.15em\TeX

A problem is that the latter is very hard to read because it is just one long line. In the source it is easier to read because it is indented. It reads:

\DeclareRobustCommand{\LaTeX}{L\kern-.36em%
        {\sbox\z@ T%
         \vbox to\ht\z@{\hbox{\check@mathfonts
                              \fontsize\sf@size\z@
                              \math@fontsfalse\selectfont
                              A}%
                        \vss}%
        }%
        \kern-.15em%
        \TeX}

Is it possible to make texdef return indented definitions?

Indented definitions are much easier to read. Also, indented definitions are preferable if you want to use them as a base for a redefinition because you do not have to indent them yourself to be able to efficiently work with them.

Answer 1

Since v1.5 (04/2012) there exists the -s/--source option which will try to locate the (first) original definition of the macro and display it as it is written in the source file. However, this will not work with all macros due to the dynamic nature of TeX. Especially verbatim and similar special macros can't be properly parsed by texdef. If this features fails the definition is printed the "normal" way, so it is save to use this option in any case.

For the example \LaTeX macro this looks as follows:

$ latexdef -s LaTeX
% latex.ltx, line 1328:
\DeclareRobustCommand{\LaTeX}{L\kern-.36em%
        {\sbox\z@ T%
         \vbox to\ht\z@{\hbox{\check@mathfonts
                              \fontsize\sf@size\z@
                              \math@fontsfalse\selectfont
                              A}%
                        \vss}%
        }%
        \kern-.15em%
        \TeX}

If the -F option is used in addition the full file path is displayed, which can be useful if you want to have a closer look at the source.

$ latexdef -Fs LaTeX
% /home/texlive/2012/texmf-dist/tex/latex/base/latex.ltx, line 1328:
\DeclareRobustCommand{\LaTeX}{L\kern-.36em%
...

Answer 2

In order to show definitions of commands, texdef runs (La)TeX with an appropriate preamble. Then it uses the primitive \meaning to show on screen the definition. The output of \meaning for a macro is

<token>:
<prefixes> macro:<parameter text>-><replacement text>

In cases of a "robusted command" texdef shows also the internal command, which is why you get two lines from texdef -t latex LaTeX:

\LaTeX:
macro:->\protect \LaTeX  

\LaTeX :
\long macro:->L\kern -.36em{\sbox \z@ T\vbox to\ht \z@ {\hbox {\check@mathfonts \fontsize \sf@size \z@ \math@fontsfalse \selectfont A}\vss }}\kern -.15em\TeX 

texdef does not look into the files, which would be almost meaningless anyway: commands can change their meaning (think to \maketitle, that is defined twice by article.cls depending on the options) or may be defined in ways very different from \def\macro or \newcommand macro.

For example, you would never find \def\mathrm, \newcommand\mathrm or \DeclareRobustCommand\mathrm, as \mathrm is (by default) defined by

\DeclareSymbolFontAlphabet{\mathrm}{operators}

The same holds for many math commands. Thus "finding the exact place where a command is defined" is in general hopeless.

One might think about filtering the output with a "code beautifier", if such a tool were generally available in Perl distributions (this could indeed be a nice feature for texdef).