Definitions, Numbering

B.8 Definitions, Numbering

B.8.1 Defining Commands

H^EV^EA understands command definitions given in L^AT_EX style. Such definitions are made using \newcommand, \renewcommand and \providecommand. These three constructs accept the same arguments and have the same meaning as in L^AT_EX, in particular it is possible to define an user command with one optional argument. However, H^EV^EA is more tolerant: if command name already exists, then a subsequent \newcommand{name}…is ignored. If macro name does not exists, then \renewcommand{name}…performs a definition of name. In both cases, L^AT_EX would crash, H^EV^EA just issues warnings.

The behaviour of \newcommand allows to shadow document definition, provided the new definitions are processed before the document definitions. This is easily done by grouping the shadowing definition in a specific style file given as an argument to H^EV^EA (see section 5.1). Conversely, changes of base macros (i.e. the ones that H^EV^EA defines before loading any user-specified file) must be performed using \renewcommand.

Scoping rules apply to macros, as they do in L^AT_EX. Environments and groups define a scope and command definition are local to the scope they occur.

It is worth noticing that H^EV^EA also partly implements T_EX definitions (using \def) and bindings (using \let), see section B.16.1 for details.

B.8.2 Defining Environments

H^EV^EA accepts environment definitions and redefinitions by \newenvironment and \renewenvironment. The support is complete and should conform to [L^AT_EX, Sections C.8.2].

Environments define a scope both for commands and environment definitions.

B.8.3 Theorem-like Environments

New theorem-like environments can also be introduced and redefined, using \newtheorem and \renewtheorem.

Note that, by contrast with plain environments definitions, theorem-like environment definitions are global definitions.

B.8.4 Numbering

L^AT_EX counters are (fully ?) supported. In particular, defining a counter cmd with \newcounter{cmd} creates a macro \thecmd that outputs the counter value. Then the \thecmd command can be redefined. For instance, section numbering can be turned into alphabetic style by:

\renewcommand{\thesection}{\alph{section}}

Note that T_EX style for counters is not supported at all and that using this style will clobber the output. However, H^EV^EA implements the calc package that makes using T_EX style for counters useless in most situations (see section B.17.3).

B.8.5 The ifthen Package

The ifthen package is partially supported. The one unsupported construct is the \lengthtest test expression, which is undefined.

As a consequence, H^EV^EA accepts the following example from the L^AT_EX manual:

\newcounter{ca}\newcounter{cb}%
\newcommand{\printgcd}[2]{%
  \setcounter{ca}{#1}\setcounter{cb}{#2}%
  Gcd(#1,#2) =
  \whiledo{\not\(\value{ca}= \value{cb}\)}%
    {\ifthenelse{\value{ca}>\value{cb}}%
      {\addtocounter{ca}{-\value{cb}}}%
      {\addtocounter{cb}{-\value{ca}}}%
    gcd(\arabic{ca}, \arabic{cb}) = }%
  \arabic{ca}.}%
For example: \printgcd{54}{30}

For example: Gcd(54,30) = gcd(24, 30) = gcd(24, 6) = gcd(18, 6) = gcd(12, 6) = gcd(6, 6) = 6.

Additionally, a few boolean registers are defined by H^EV^EA. Some of them are of interest to users.

hevea: Initial value is true. The hevea.sty style file also defines this register with initial value false.
mmode: This register value reflects H^EV^EA operating mode, it is true in math-mode and false otherwise.
display: This register value reflects H^EV^EA operating mode, it is true in display-mode and false otherwise.
footer: Initial value is true. When set false, H^EV^EA does not insert its footer “This document has been translated by H^EV^EA”.

Finally, note that H^EV^EA also recognised à la T_EX conditional macros (see section B.16.1.4). Such macros are fully compatible with the boolean registers of the ifthen package, as it is the case in L^AT_EX.