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functions [ {+|-}UkmtTuWz ] [ -x num ] [ name ... ]
functions -c oldfn newfn
functions -M [-s] mathfn [ min [ max [ shellfn ] ] ]
functions -M [ -m pattern ... ]
functions +M [ -m ] mathfn ...
Equivalent to typeset -f, with the exception of the -c, -x, -M
and -W options. For functions -u and functions -U, see au-
toload, which provides additional options. For functions -t and
functions -T, see typeset -f.
The -x option indicates that any functions output will have each
leading tab for indentation, added by the shell to show syntac-
tic structure, expanded to the given number num of spaces. num
can also be 0 to suppress all indentation.
The -W option turns on the option WARN_NESTED_VAR for the named
function or functions only. The option is turned off at the
start of nested functions (apart from anonoymous functions) un-
less the called function also has the -W attribute.
The -c option causes oldfn to be copied to newfn. The copy is
efficiently handled internally by reference counting. If oldfn
was marked for autoload it is first loaded and if this fails the
copy fails. Either function may subsequently be redefined with-
out affecting the other. A typical idiom is that oldfn is the
name of a library shell function which is then redefined to call
newfn, thereby installing a modified version of the function.
The -M and +M flags
Use of the -M option may not be combined with any of the options
handled by typeset -f.
functions -M mathfn defines mathfn as the name of a mathematical
function recognised in all forms of arithmetical expressions;
see the section `Arithmetic Evaluation' in zshmisc(1). By de-
fault mathfn may take any number of comma-separated arguments.
If min is given, it must have exactly min args; if min and max
are both given, it must have at least min and at most max args.
max may be -1 to indicate that there is no upper limit.
By default the function is implemented by a shell function of
the same name; if shellfn is specified it gives the name of the
corresponding shell function while mathfn remains the name used
in arithmetical expressions. The name of the function in $0 is
mathfn (not shellfn as would usually be the case), provided the
option FUNCTION_ARGZERO is in effect. The positional parameters
in the shell function correspond to the arguments of the mathe-
matical function call.
The result of the last arithmetical expression evaluated inside
the shell function gives the result of the mathematical func-
tion. This is not limited to arithmetic substitutions of the
form $((...)), but also includes arithmetical expressions evalu-
ated in any other way, including by the let builtin, by ((...))
statements, and even by the return builtin and by array sub-
scripts. Therefore, care must be taken not to use syntactical
constructs that perform arithmetic evaluation after evaluating
what is to be the result of the function. For example:
# WRONG
zmath_cube() {
(( $1 * $1 * $1 ))
return 0
}
functions -M cube 1 1 zmath_cube
print $(( cube(3) ))
This will print `0' because of the return.
Commenting the return out would lead to a different problem: the
((...)) statement would become the last statement in the func-
tion, so the return status ($?) of the function would be
non-zero (indicating failure) whenever the arithmetic result of
the function would happen to be zero (numerically):
# WRONG
zmath_cube() {
(( $1 * $1 * $1 ))
}
functions -M cube 1 1 zmath_cube
print $(( cube(0) ))
Instead, the true builtin can be used:
# RIGHT
zmath_cube() {
(( $1 * $1 * $1 ))
true
}
functions -M cube 1 1 zmath_cube
print $(( cube(3) ))
If the additional option -s is given to functions -M, the argu-
ment to the function is a single string: anything between the
opening and matching closing parenthesis is passed to the func-
tion as a single argument, even if it includes commas or white
space. The minimum and maximum argument specifiers must there-
fore be 1 if given. An empty argument list is passed as a
zero-length string. Thus, the following string function takes a
single argument, including the commas, and prints 11:
stringfn() { (( $#1 )); true }
functions -Ms stringfn
print $(( stringfn(foo,bar,rod) ))
functions -M with no arguments lists all such user-defined func-
tions in the same form as a definition. With the additional op-
tion -m and a list of arguments, all functions whose mathfn
matches one of the pattern arguments are listed.
function +M removes the list of mathematical functions; with the
additional option -m the arguments are treated as patterns and
all functions whose mathfn matches the pattern are removed.
Note that the shell function implementing the behaviour is not
removed (regardless of whether its name coincides with mathfn).
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