5.1.4 Command-Output Delimiters

Warning: This is a deprecated feature.

Every MOO network connection has associated with it two strings, the output prefix and the output suffix. Just before executing a command typed on that connection, the server prints the output prefix, if any, to the player. Similarly, just after finishing the command, the output suffix, if any, is printed to the player. Initially, these strings are not defined, so no extra printing takes place.

The PREFIX and SUFFIX commands are used to set and clear these strings. They have the following simple syntax:

PREFIX output-prefix SUFFIX output-suffix

That is, all text after the command name and any following spaces is used as the new value of the appropriate string. If there is no non-blank text after the command string, then the corresponding string is cleared. For compatibility with some general MUD client programs, the server also recognizes OUTPUTPREFIX as a synonym for PREFIX and OUTPUTSUFFIX as a synonym for SUFFIX.

These commands are intended for use by programs connected to the MOO, so that they can issue MOO commands and (somewhat) reliably determine the beginning and end of the resulting output. For example, one editor-based client program sends this sequence of commands on occasion:

PREFIX >>MOO-Prefix<< SUFFIX >>MOO-Suffix<< @list object:verb without numbers PREFIX SUFFIX

The effect of which, in a LambdaCore-derived database, is to print out the code for the named verb preceded by a line containing only `>>MOO-Prefix<<' and followed by a line containing only `>>MOO-Suffix<<'. This enables the editor to (somewhat) reliably extract the program text from the MOO output and show it to the user in a separate editor window. There are many other possible uses.

Warning: If the command thus bracketed calls suspend(), its output will be deemed "finished" then and there; the suffix thus appears at that point and not, as one might expect, later when the resulting background task has finally returned from its top-level verb call. Thus, use of this feature (which was designed before suspend() existed) is no longer recommended.

The built-in function output_delimiters() can be used by MOO code to find out the output prefix and suffix currently in effect on a particular network connection.