Tukukkk

According to Christian Hupfer's comment I understood that calculations are possible in a keyval list when the macro is expandable. The macro numexpr being expandable, calculations are possible.

Hence the interest in knowing which macros are and which are not expandable from TeX, LaTeX, e-TeX, etc.

I am not asking if there is a test, but if there is a list already made.

Joseph has already answered, interpreting the "expandable` in your question as "fully expandable" (or what is perhaps better named as "safe in an expansion only context" see

Advantages and disadvantages of fully expandable macros

However to answer the question as actually asked, note that numexpr is neither a macro nor expandable.

All macros are by definition expandable, a macro works by expanding to its replacement text. There is no list of these as it is any command defined via def or its variants edef, gdef, xdef.

The TeXBook lists all the TeX primitivies, these are marked by a * in the index, although you need to check the description of each individually to see if they are expandable.

In classic TeX, the expandable primitives are (I think:-)

expandafter

the

number

romannumeral

if

ifx

ifcat

ifcase

ifnum

ifodd

ifdim

ifeof

iftrue

iffalse

ifhbox

ifvbox

ifvoid

ifinner

ifvnode

ifhmode

ifmmode

else

or

fi

input % (@@input in LaTeX)

jobname

meaning

noexpand

string

topmark

firstmark

botmark

in etex the additional expandable primitives are

topmarks

firstmarks

botmarks

ifdefined

ifcsname

iffontchar

unless

eTeXrevision

unexpanded

detokenize

scantokens

in addition to all the above pdftex adds the following expandable primitives

pdfescapestring

pdfescapename

pdfescapehex

pdfstrcmp

pdfmatch

ifpdfabsnum

ifpdfabsdim

pdfuniformdeviate

pdfnormaldeviate

pdffilemoddate

pdffilesize

pdfmdffivesum

pdffiledump

pdfcolorstackinit

ifincsname

ifpdfprimitive

pdfcreationdate

pdfinsertht

pdftexbanner

pdftexrevision

expanded % (in development versions for texlive 2019)

XeTeX has the primitives of etex, and adds the following expandable primitives

ifincsname

ifprimitive

normaldeviate

uniformdeviate

filedump

filemoddate

filesize

mdfivesum

expanded  % for texlive 2019

XeTeXrevision

Uchar

Ucharcat

LuaTeX has the expandable primitives of etex plus (at least)

luatexbanner

luatexrevision

formatname

Uchar

directlua

luaescapestring

scantextokens

csstring

expanded

pdfextension

pdfvariable

pdffeedback

A list of all expandable macros is entirely impossible to provide: there are an open-ended number of cases. What one can do is provide a list of primitives which work by expansion, and general rules for macros.

Essentially, any primitives which carry out assignment or typesetting are not expandable, whilst other primitives are. Thus for example def, let, etc. are all non-expandable, as are hbox, raise, setbox, whereas expandafter, the and ifx are all expandable. Note that some primitives will be expandable in the right context: numexpr is not expandable in itself, but is a valid token coming after the or number:

edeftesta{numexpr 1+2relax}showtesta

edeftestb{numbernumexpr 1+2relax}showtestb

In terms of macros, we have to be clear what we mean by 'expandable'. TeX is a macro expansion language, so if we have for example

defbaz{}

deffoo{defbaz{bar}}

then we can do

edeftest{foo}showtest

although the result is not what is likely wanted/useful. As such, when we talk about expandable macros we normally mean macros which contain only expandable primitives and which thus can be used 'safely' inside an edef or similar. With e-TeX, it' possible to ensure that macros which don't meet this criterion don't 'blow up':

defbaz{}

protecteddeffoo{defbaz{bar}}

edeftest{foo}showtest

Where does that take us? Any macro which contains:

• Any assignment primitive


• Any typesetting primitive


• Any protected macro


• Any macro which itself meets one of the three criteria above

is not expandable. That is the majority of 'useful' macros, so as mentioned in comments, if you are not sure, assume non-expandable.

Note that the list of non-expandable primitives is quite long, and we do have to remember about the context. For example, something like tracingcommands acts like a count register, so is non-expandable unless if follows the. Thus unless we implement a token-by-token processor, just seeing tracingcommands doesn't tell us that a macro containing this token is not expandable.

deffoo{tracingcommands=1 }% Not expandable

defbaz{thetracingcommands}% Expandable

In LaTeX3/expl3, all macros are either fully expandable or are protected. Moreover, the expandable ones are all marked as such (with a star) in the documentation. The reason is that it requires some knowledge to see if something is expandable, in particular checking all macro 'dependencies'. As such, one has to work carefully to track expandable macros.