assign command

Synopsis

/assign
/assign <name-or-prefix>
/assign -<name>
/assign <name> <value>

Description

assign is the general-purpose command for creating and changing variables, particularly text values. EPIC stores user variables as strings. A value used in a numeric expression is converted to a number as needed; assigning it does not give the variable a permanent numeric type.

With no arguments, assign lists global user variables. With a name or prefix and no value, it lists matching global variables, case-insensitively. Dotted descendants may appear grouped as <Structure> entries; use a more specific prefix to see individual values. These forms do not list local variables or built-in settings.

With a name and nonempty value, it creates or replaces the variable and normally prints a confirmation. Whitespace before the value is skipped; the remaining text is stored as supplied to the handler, without removing quotation marks. Normal $ expansion may already have occurred before the handler runs, depending on the calling context.

With only -name, it removes that exact global user variable. It does not remove every variable sharing a prefix, a same-name command alias, or a local variable. /assign - reports that a name is required. If no matching symbol exists, the command reports No such assign.

The command has no options, is available in every build, and needs no server connection.

Names and scope

Names are case-insensitive; values preserve their text and case. The normal name characters accepted by the implementation are letters, digits, underscores, and dots. A leading letter is not required, but names beginning with a letter or underscore are easier to reference because numbered expandos such as $0 have another meaning. Invalid characters produce an error rather than an assignment.

Square brackets are converted to dot notation: foo[bar][baz] becomes foo.bar.baz.

An ordinary assignment updates a visible local variable if one exists; otherwise it creates or updates a global variable. Prefix the name with : to force local assignment or :: to force global assignment:

assign :name local value
assign ::name global value

function_return is special: assignment routes it to the local return-value machinery even with the global prefix. See alias for function return behavior. The -name deletion form goes directly to global deletion and does not implement these scope prefixes.

To create local variables explicitly, see local. Listing with assign always examines global variables, even when an ordinary assignment would update a local variable.

Expressions and empty values

assign is primarily useful for string assignments. Use ${...} where command expansion is active to insert the result of an expression. For arithmetic or an explicitly empty value, use an expression statement instead:

@ foo = 4 + 5
@ foo = []

/assign foo lists variables rather than setting foo to an empty string. Quoting an empty value as "" passes quotation characters to this handler; it is not an empty-value syntax. See expressions.

Examples

To assign a text string to $foo:

assign foo this is some text string

To compute the sum of two integers in a script context that expands ${...}:

assign foo ${4 + 5}

To list matching global variables and then delete foo:

assign foo
assign -foo

At the interactive input prompt, prefix command forms with /.

History

The assign command first appeared in ircII.

Source

See source/alias.c: assigncmd(), add_var_alias(), add_local_alias(), find_local_alias(), list_var_alias(), and delete_var_alias(). source/ircaux.c implements name canonicalization and validation in remove_brackets() and after_expando(). source/commands.c implements expansion before command dispatch.