Module texlang_stdlib::prefix

The \global, \long and \outer prefix commands

Global

The \global command makes the subsequent assignment global; i.e., not scoped to the current group. This command checks that the subsequent command is allowed to be prefixed by global and then sets a \global bit. All commands that can be prefixed then consume this bit by calling the hook TexlangState::variable_assignment_scope_hook.

In order for this to work correctly it is essential that all code paths within the command call the hook - even if the result is not used! For example \gdef always creates a macro in the global scope, but it still needs to call the hook. Otherwise the global bit will still be set, and the next assignment may be incorrectly performed in the global scope.

This behavior should be verified with unit tests. This module provides an assert_global_is_false execution command to make this easy - the command just raises an error if the global bit is still true.

Outer and long

The \long and \outer commands are designed to place restrictions on macros to avoid performance problems. These restrictions are described in the TeXBook. Texlang does not currently impose these restrictions. However, Texlang does enforce the rule that these prefix commands can only come before \def, \gdef, \edef and \xdef.

Structs

• Component
  Component for the prefix commands.

Functions

• get_assert_global_is_false
  Get an execution command that checks that the global flag is off.
• get_global
  Get the \global command.
• get_globaldefs
  Get the \globaldefs command.
• get_long
  Get the \long command.
• get_outer
  Get the \outer command.
• variable_assignment_scope_hook
  Implementation of the variable assignment scope hook.