Rinci::function(3pm) User Contributed Perl Documentation Rinci::function(3pm)NAMERinci::function - Metadata for your functions/methods
VERSION
version 1.1.43
SPECIFICATION VERSION
1.1
INTRODUCTION
This document describes metadata for functions/methods. Since the
metadata properties describe features and the way a function works,
this document also describes how a function should support those
properties.
This specification is part of Rinci. Please do a read up on it first,
if you have not already done so.
SPECIFICATION
Result envelope. Function should return an enveloped result to express
error code/message as well as actual result. The envelope can be
produced by the function itself, or added by a wrapper tool. Result
envelope is modeled after HTTP or PSGI response; it is an array in the
following format:
[STATUS, MESSAGE, RESULT, META]
STATUS is a 3-digit integer, much like HTTP response status code and is
explained further in "Envelope status codes". MESSAGE is a string
containing error message. RESULT (or PAYLOAD) is the actual content to
be returned and can be omitted or set to undef if the function does not
need to return anything. META is called result metadata, a defhash
containing extra data, analogous to HTTP response headers. Result
metadata is specified further in Rinci::result.
Some example of an enveloped results:
[200, "OK", 42]
[404, "Not found"]
[500, "Can't delete foo: permission denied", {errno=>51}]
[200, "Account created", {id=>9323},
{undo_calls=>[["delete_account", {id=>9323}]]}]
As mentioned, an enveloped result can contain error code/message as
well as the actual result. It can also be easily converted to HTTP
response message. And it can also contain extra data, useful for things
like the transaction protocol (explained in Rinci::Transaction).
Special arguments. Special arguments are some known arguments that
start with dash ("-") and serve special purposes. You need not specify
them in the "args" metadata property. Examples of special arguments
include "-dry_run", "-tx_action", and they will be explained in other
related sections/documents.
Functions vs methods. Since in many programming languages (like Perl 5,
Python, Ruby, PHP) static functions are not that differentiated from
methods, functions and methods share the same Rinci spec. But there are
certain properties that can be used to declare if a function is (also)
a method or not. See "is_func", "is_meth", "is_class_meth" properties
below for details.
Multiple dispatch. This specification also does not (yet) have any
recommendation on how to best handle functions in languages that
support multiple dispatch, like Perl 6: whether we should create
multiple metadata or just one. It is more up to the tool and what you
want to do with the metadata.
Envelope status codes
In general, status codes map directly to HTTP response status codes.
Below are the suggestion on which codes to use (or avoid). An asterisk
("*") marks which codes are not defined in HTTP specification and
introduced by this specification.
· 1xx code
Currently not used.
· 2xx code - success
200 should be used to mean success.
206 can be used to signal partial content, for example: a
"read_file()" function which accepts "byte_start" and "byte_end"
arguments should return 206 when only partial file content is
returned. But in general, use 200 as some callers will simply check
for this exact code (instead of checking for range 200-299).
· 3xx code - further actions needs to be taken by user agent (caller)
301 (moved) can be used to redirect callers to alternate location,
although this is very rare.
304 (not modified, nothing done). Used for example by setup
functions to indicate that nothing is being modified or no
modifying action has been performed (see Setup::* modules in CPAN).
331* (confirmation required). Function requires confirmation, for
example if action to be taken is dangerous or requires user's
attention. Confirmation message/prompt from function can be
returned in the message, or in the "confirm_prompt" property (e.g.
to provide translations). Confirmation from caller is in the form
of special argument "-confirm" with boolean value of true (TODO: A
more detailed confirmation for different actions can be specified
later in the form of "-confirm_XXX" special arguments.) For an
example of application of this, see Perinci::Tx::Manager.
· 4xx code - client (caller) side error
400 (bad request, bad arguments) should be returned when the
function encounters invalid input. A function wrapper can return
this code when the function arguments fail the argument schema
validation (specified in the "args" property).
401 (authentication required).
403 (forbidden, access denied, authorization failed).
404 (not found). Can be used for example by an object-retrieval
functions (like "get_user()") and the object is not found.
For object-listing functions (like "list_users()"), when there are
no users found matching the requested criteria, 200 code should
still be returned with an empty result (like an empty array or
hash).
Also in general, an object-deletion function (like "delete_user()")
should also return 200 (or perhaps 304, but 200 is preferred)
instead of 404 when the object specified to be deleted is not
found, since the goal of the delete function is reached anyway.
408 (request timeout).
409 (conflict). Can be used for example by a "create_user()"
function when receiving an already existing username.
412 (precondition failed). Similar to 409, but can be used to
indicate lack of resources, like disk space or bandwidth. For
lacking authentication and authorization, use 401 and 403
respectively.
429 (too many requests).
(EXPERIMENTAL) 44x codes are reserved for function-specific codes.
Each function is free to define what each number means. However,
this is not really encouraged and should only be used if necessary.
Function should perhaps stick to predefined codes here. To return
more detailed status, result metadata can be used.
480* is general transaction error, e.g. transaction status is
aborted so further requests for this transaction is ignored until
transaction is aborted.
484* (no such transaction).
· 5xx code - server (callee) side error
500 is the general code to use when a failure occurs during the
execution of a function. for example when a "delete_file()"
function fails to delete specified file (though in this case it can
also choose to return 403 instead, which is more specific).
501 (not implemented)
503 (service unavailable). You can use this when service is
temporarily unavailable, e.g. when system load is too high, a
required service is down, etc. Users should try again at a later
time.
507 (insufficient storage)
521 (maximum retries reached)
531* (bad metadata) is used when there is something wrong with the
metadata.
532* (failure in recording transaction) when there is a failure in
updating transaction status or in preparing/committing/rolling back
the transaction.
(EXPERIMENTAL) 54x codes are reserved for function-specific codes.
Each function is free to define what each number means. However,
this is not really encouraged and should only be used if necessary.
Function should perhaps stick to predefined codes here. To return
more detailed status, result metadata can be used.
Try not to use code greater than 555, as some tools use (CODE-300)
for error codes that must fit in one unsigned byte (like
Perinci::CmdLine).
Property: is_func => BOOL
Specify that the function can be called as a static function (i.e.
procedural, not as a method). Default is true if unspecified, but
becomes false if is_meth or is_class_meth is set to true.
Example:
# specify that function can be called a method *as well as* a static function
is_meth => 1
is_func => 1 # if not specified, will default to false after is_meth set to 1
Property: is_meth => BOOL
Specify that the function can be called as an instance (object) method.
Default is false.
Example:
# specify that function is a method
is_meth => 1
Property: is_class_meth => BOOL
Specify that the function can be called as a class method. Examples of
class methods include the constructor, but there are others. Default is
false.
Example:
# specify that function is a class method
is_class_meth => 1
Property: args => HASH
Specify arguments. Property value is defhash of argument names and
argument specification. Argument name must only contain letters,
numbers, and underscores (and do not start with a number).
Argument specification is a hash containing these keys:
· schema => SCHEMA
Data::Sah schema for argument value.
· default => ANY
Give default value for argument. This takes precedence over schema,
which can also specify default value. This is useful if you want to
share a common schema over several arguments but want to have
different default for each argument. For example, you have a
"ticket_status" schema. In "create_ticket" function you want the
default "status" argument to be "new", while in "reply_ticket" you
want the default "status" to be "answered".
· summary => STR
From DefHash. A one-line plaintext summary, much like the "summary"
property in variable metadata.
· req => BOOL
Specify that argument is required (although its value can be
undef/null). Default is false.
· description => STR
From DefHash. A longer description of marked up text, much like the
"description" property. It is suggested to format the text to 74
columns.
· tags => ARRAY OF (STR|HASH)
From DefHash. An array of tags, can be used by tools to categorize
arguments. Not unlike the "tags" property.
· pos => INT
Argument position when specified in an ordered fashion, e.g. in an
array. Starts from zero.
· greedy => BOOL
Only relevant if pos is specified, specify whether argument should
gobble up all remaining values in an ordered argument list into an
array.
· cmdline_aliases => HASH
Specify aliases for use in command-line options (or other possibly
suitable situation where arguments are parsed from command-line-
like options). Keys are alias names, values are itself hashes
(alias specification). Valid alias specification keys: "summary" (a
string, optional), "schema" (optional, defaults to argument's
schema), "code" (a code to set argument value, optional, will be
given "(\%args, $val)"); if not set, the default behavior is simply
to set the argument value).
· cmdline_on_getopt => CODE
A hook that will be called when argument is specified as a command-
line option. In Perl, hook will be called with a hash argument
containing this key: "arg" (str, argument name), "value" (str,
option value), "args" (hash, the argument hash defined so far).
This can be useful if you want to process a command-line option
directly on a per-option basis instead of getting the final
resulting argument value. For example (in Perl):
args => {
library => {
schema => ['array*' => of => 'str*'],
cmdline_aliases => { I => {} },
cmdline_on_getopt => sub {
my %args = @_;
require lib;
lib->import($args{value});
},
},
module => {
schema => ['array*' => of => 'str*'],
cmdline_aliases => { M => {} },
cmdline_on_getopt => sub {
my %args = @_;
require Module::Load;
Module::Load::load($args{value});
},
},
}
With command-line argument like this:
-I dir1 -M mod1 -I dir2 -M mod2
Without any "cmdline_on_getopt" hooks, the function will receive
this argument hash:
{ library => ['dir1', 'dir2'], module => ['mod1', 'mod2'] }
but there is no way to know the order of options being specified in
the command-line. With the hooks, the function can load modules
correctly (e.g. loading "mod1" won't search in "dir2" as that
directory has not been added by -I).
· cmdline_on_getarg => CODE
Like "cmdline_on_getopt" but will be called when argument is
specified as a command-line argument. For example:
args => {
foo => {
schema => ['array*' => of => 'str*'],
pos => 0,
greedy => 1,
cmdline_on_getopt => sub { ... },
cmdline_on_getarg => sub { ... },
},
bar => { ... },
},
and the command-line argument:
--foo o1 --bar o2 --foo o3 a1 a2
The "cmdline_on_getopt" hook will be called twice for "o1" and
"o3", while the "cmdline_on_getarg" hook will be called twice with
"a1" and "a2".
· completion => CODE
A code to supply argument value completion. Will be explained in
the examples.
· element_completion => CODE
A code to supply argument element value completion. Only applicable
if argument type is "array". Will be explained in the examples.
· cmdline_src => STR
Specify how to get the value for this argument, when function is
run as a command-line program. Valid values include: "file"
(command-line argument value will be treated as filename and
function argument will be set to content of the file), "stdin"
(means that program should get function argument from standard
input), or "stdin_or_files" (means that program should get value
from content of files, or if none is specified, from standard
input). Other sources might be defined in the future.
If function argument's type is "str" or "array", the whole standard
input and files will be slurped into memory. If function argument's
type is "stream" or "filehandle", program should provide standard
input and files as a filehandle (like the diamond operator in Perl)
so function can read input one record at a time. Record is line,
but specifying the record separator should perhaps be possible in
the future.
There should only be one argument with "src" set to "stdin" or
"stdin_or_files".
TODO: Define "web_src" property and source for streaming web
application.
TODO: A way to define record separator.
Example function metadata and its implementation in Perl:
$SPEC{multiply2} = {
v => 1.1,
summary => 'Multiple two numbers',
args => {
a => {
summary => 'The first operand',
description => '... a longer description ...',
schema=>'float*',
pos => 0,
tags => ['category:operand'],
},
b => {
summary => 'The second operand',
description => '... a longer description ...',
schema => 'float*',
pos => 1,
tags => ['category:operand'],
},
round => {
summary => 'Whether to round result',
description => '... a longer description ...',
schema => [bool => {default=>0}],
pos => 2,
tags => ['category:options'],
cmdline_aliases => {
r=>{},
R=>{summary=>'Equivalent to --round=0',
code=>sub {$_[0]{round}=0}},
},
},
}
};
sub multiply2 {
my %args = @_;
my $res = $args{a} * $args{b};
$res = int($res) if $round;
[200, "OK", $res];
}
By default, without any wrapper, the function is called with a named
hash style:
multiply2(a=>4, b=>3); # 12
But with the information from the metadata, a wrapper tool like
Perinci::Sub::Wrapper is able to change the calling style to
positional:
multiply2(4, 3.1, 1); # 12
A command-line tool will also enable the function to be called named
options as well as positional arguments:
% multiply2 --a 2 --b 3
% multiply2 2 --b 3
% multiply2 2 3
As mentioned earlier, "cmdline_alises" is parsed by command-line option
parser:
% multiply2 2 3.5 -r ; # equivalent to multiply2 2 3 --round
% multiply2 2 3.5 -R ; # equivalent to multiply2 2 3 --noround (--round=0)
Aliases in "cmdline_aliases" are not recognized as real arguments:
multiply2(a=>4, b=>3, r=>0); # unknown argument r
Another example (demonstrates "cmdline_aliases"):
$SPEC{smtpd} = {
v => 1.1,
summary => 'Control SMTP daemon',
args => {
action => {
schema => ['str*' => {in=>[qw/status start stop restart/]}],
pos => 0,
req => 1,
cmdline_aliases => {
status => {
schema => [bool=>{is=>1}],
summary => 'Alias for setting action=status',
code => sub { $_[0]{action} = 'status' },
},
start => {
schema => [bool=>{is=>1}],
summary => 'Alias for setting action=start',
code => sub { $_[0]{action} = 'start' },
},
stop => {
schema => [bool=>{is=>1}],
summary => 'Alias for setting action=stop',
code => sub { $_[0]{action} = 'stop' },
},
restart => {
schema => [bool=>{is=>1}],
summary => 'Alias for setting action=restart',
code => sub { $_[0]{action} = 'restart' },
},
},
},
force => {
schema => 'bool',
},
},
};
Another example (demonstrates greedy):
$SPEC{multiply_many} = {
v => 1.1,
summary => 'Multiple numbers',
args => {
nums => {
schema => ['array*' => {of=>'num*', min_len=>1}],
pos => 0,
greedy => 1
},
},
};
sub multiply_many {
my %args = @_;
my $nums = $args{nums};
my $ans = 1;
$ans *= $_ for @$nums;
[200, "OK", $ans];
}
After wrapping, in positional mode it can then be called:
multiply_many(2, 3, 4); # 24
which is the same as (in normal named-argument style):
multiply_many(nums => [2, 3, 4]); # 24
In command-line:
% multiply-many 2 3 4
in addition to the normal:
% multiply-many --nums '[2, 3, 4]'
completion. This argument specification key specifies how to complete
argument value (e.g. in shell or Riap::HTTP) and is supplied an
anonymous function as value. The function will be called with
arguments: word=>... (which is the formed word so far, ci=>0|1 (whether
completion should be done case-insensitively). The function should
return an array containing a list of possible candidates. For an
example of implementation for this, see Perinci::Sub::Complete in Perl
which provides tab completion for argument values. Example:
$SPEC{delete_user} = {
v => 1.1,
args => {
username => {
schema => 'str*',
pos => 0,
completion => sub {
my %args = @_;
my $word = $args{word} // "";
# find users beginning with $word
local $CWD = "/home";
return [grep {-d && $_ ~~ /^\Q$word/} <*>];
},
},
force => {schema=>[bool => {default=>0}]},
},
};
When "delete_user" is executed over the command line and the Tab key is
pressed:
$ delete-user --force --username fo<tab>
$ delete-user fo<tab>
then bash will try to complete with usernames starting with "fo".
element_completion. This is like completion, but for array elements.
Argument type must be "array". Example:
$SPEC{delete_users} = {
v => 1.1,
args => {
usernames => {
schema => ['array*' => of => 'str*'],
req => 1,
pos => 0,
greedy => 1,
element_completion => sub {
my %args = @_;
my $word = $args{word} // "";
# find users beginning with $word
local $CWD = "/home";
my $res = [grep {-d && $_ ~~ /^\Q$word/} <*>];
# exclude users already mentioned by user
my $ary = $args{args}{usernames};
$res = [grep {!($_ ~~ @$ary)}] @$res;
return $res;
},
},
},
};
When "delete_users" is executed over the command line:
$ delete-users c<tab> ; # will complete with all users beginning with c
$ delete-users charlie c<tab> ; # will complete with users but exclude charlie
$ delete-users charlie chucky <tab> ; # and so on
Property: args_as => STR
Specify in what form the function expects the arguments. The value is
actually implementation-specific since it describes the function
implementation. For example in Perinci for Perl, these values are
recognized: "array", "hash", "arrayref", "hashref". This property is
useful for wrapper to be able to convert one form to another.
The default value is also left to the implementation.
For interimplementation communication (e.g. via Riap::HTTP or
Riap::TCP), named arguments are always used so this property is
irrelevant.
Property: result => HASH
Specify function return value. It is a defhash containing keys:
· summary
From DefHash. Like the "summary" property in variable metadata.
· description
From DefHash. Like the "description" property. Suggested to be
formatted to 78 columns.
· schema => SCHEMA
A Sah schema to validate the result (the third element in the
envelope result). This schema should only be tested if status is
200. See also: "statuses".
· statuses => HASH
Can be used to specify different result schema for different
statuses. For example:
statuses => {
206 => {
schema => 'str*',
},
}
Note that since functions normally return enveloped result, instead of
returning:
RESULT
your functions normally have to return an enveloped result:
[STATUS, MESSAGE, RESULT, METADATA]
Examples:
# result is an integer
result => {schema => 'int*'}
# result is an integer starting from zero
result => {schema => ['int*' => {ge=>0}]}
# result is an array of records
result => {
summary => 'Matching addressbook entries',
schema => ['array*' => {
summary => 'blah blah blah ...',
of => ['hash*' => {allowed_keys=>[qw/name age address/]} ]
}]
}
Property: result_naked => BOOL
If set to true, specify that function does not envelope its results.
The default is false, to encourage functions to create envelopes.
However, wrapper should be able to create or strip envelope if needed.
For example, if you have "traditional" functions which does not do
envelopes, you can set this property to true, and the wrapper can
generate the envelope for the functions.
Property: examples => ARRAY
This property allows you to put examples in a detailed and structured
way, as an alternative to putting everything in "description".
Each example is a defhash, it specifies what arguments are used, what
the results are, and some description. It can be used when generating
API/usage documentation, as well as for testing data. It can also be
used for testing (function will be run with specified arguments and the
result will be matched against expected result). Known properties:
· args => HASH
Arguments used to produce result. Can be converted to "argv" by
tool, e.g. when displaying command-line eamples
· argv => ARRAY
An alternative to "args", for example when function is run from the
command-line. Can be converted to "args" most of the time when
wanting to display examples in Perl instead of command-line.
· src => STR
An alternative to "args" or "argv", to provide raw source code. See
also: "src_plang". This can be used to show more general examples.
For example, you can show how a function is used in an expression
or code block, or how a command-line program is used in a shell
script.
Exactly one of "args", "argv", or "src" must be specified.
· src_plang => STR
The programming language the examples source code "src" is written
in. Valid values include: "perl", "bash".
Command-line interface tools will typically only show examples
written in "bash" or other shells, while Perl module tools will
typically only show "perl" examples.
Required if "src" is specified.
· status => INT (default: 200)
Status from envelope. If unspecified, assumed to be 200.
· result => DATA
Expected result.
· summary => STR
From DefHash. A one-line summary of the example You should
describe, in one phrase or sentence, what the example tries to
demonstrate. You can skip the summary if the example is pretty
basic or things are already clear from the "args" alone.
· description => STR
From DefHash. Longer marked up text about the example (e.g.
discussion or things to note), suggested to be formatted to 72
columns.
· tags => ARRAY
From DefHash.
· test => BOOL (default: 1)
Whether to actually test example or not. Examples are by default
run as tests by a test module (e.g. Perl module Test::Rinci.
Setting this to 0 disables this example from being included in a
test.
TODO: more detailed testing instruction (e.g. only test in release
candidate, or under certain environment flag, etc).
Example:
# part of metadata for Math::is_prime function
examples => [
{
args => {num=>10},
result => 0,
# summary no needed here, already clear.
},
{
args => {},
result => 400,
summary => 'Num argument is required',
},
{
argv => [-5],
result => 1,
summary => 'Also works for negative integers',
},
],
Another example demonstrating "src" for a function called
"list_countries":
examples => [
{
src => 'for c in `list-countries`; do wget http://flags.org/country/$c; done',
src_plang => 'bash',
},
{
src => <<'EOT',
my $res = list_countries(detail => 1, sort=>['-popsize']);
die "Can't list countries: $res->[0] - $res->[1]" unless $res->[0] == 200;
my $i = 0;
for my $c (@{ $res->[2] }) { $i++; say "$i. $_->{name}'s population: $_->{popsize}";
EOT
src_plang => 'perl',
},
],
Property: features => HASH
The "features" property is a deffhash. It allows functions to express
their features. Each hash key contains feature name, which must only
contain letters/numbers/underscores.
Below is the list of defined features. New feature names may be defined
by extension.
· feature: reverse => BOOL (default: 0)
If set to true, specifies that function supports reverse operation.
To reverse, caller can add special argument "-reverse". For
example:
$SPEC{triple} = {
v => 1.1,
args => {num=>{schema=>'num*'}},
features => {reverse=>1}
};
sub triple {
my %args = @_;
my $num = $args{num};
[200, "OK", $args{-reverse} ? $num/3 : $num*3];
}
triple(num=>12); # => 36
triple(num=>12, -reverse=>1); # => 4
· feature: tx => HASH
Default is none. Specify transactional support, as specified in
Rinci::Transaction. Value is a hash containing these keys: "v"
(int, protocol version, default if not specified is 1).
Please see Rinci::Transaction for more details on transaction.
· feature: dry_run => BOOL (default: 0)
Default is false. If set to true, specifies that function supports
dry-run (simulation) mode. Example:
use Log::Any '$log';
$SPEC{rmre} = {
summary => 'Delete files in curdir matching a regex',
args => {re=>{schema=>'str*'}},
features => {dry_run=>1}
};
sub rmre {
my %args = @_;
my $re = qr/$args{re}/;
my $dry_run = $args{-dry_run};
opendir my($dir), ".";
while (my $f = readdir($dir)) {
next unless $f =~ $re;
$log->info("Deleting $f ...");
next if $dry_run;
unlink $f;
}
[200, "OK"];
}
The above Perl function delete files, but if passed argument
"-dry_run" => 1 (simulation mode), will not actually delete files,
only display what files match the criteria and would have be
deleted.
Specifying a function as supporting dry_run means, among others:
· If dry_run is requested, function will have no side effects
It will behave like a pure function, and thus have the
properties of a pure function.
· feature: pure => BOOL (default: 0)
If set to true, specifies that function is "pure" and has no "side
effects" (these are terms from functional programming / computer
science). Having a side effect means changing something, somewhere
(e.g. setting the value of a global variable, modifies its
arguments, writing some data to disk, changing system date/time,
etc.) Specifying a function as pure means, among others:
· it can safely be inculded in transaction without recording in
journal;
· it can safely be included during dry run;
· feature: immutable => BOOL
Default is false. If set to true, specifies that function always
returns the same result when given the same argument values. This
enables optimization like memoization. An example of an immutable
function is "sub { $_[0]+$_[1] }" where its results only depend on
the arguments. Example of a mutable function would be "rand()" or
"read()" that reads contents from a file.
· feature: idempotent => BOOL
Default is false. If set to true, specifies that function is
idempotent. Idempotency means that repeated invocation of a
function (each with the same arguments) will have the same effect
as a single invocation. In other words, extra invocation will not
have any effect.
Some operations, like reading a database row or a file's content,
is inherently idempotent (or to be exact nullipotent). Another
example is setting or updating an entity to some specific value, or
deleting some entity. Repeated invocation of the operation will
still sets the entity to the same value, or still deletes the
entity.
Some other operations are inherently non-idempotent, for example
sending an email. Repeated invocation will cause multiple emails to
be sent.
Yet some other operations are non-idempotent, but can be made
idempotent simply by checking whether the target object(s) has
(have) reached the final desired state, (optionally additionally
also checking whether they are in the correct original state to
begin with). For example, a function that renames a file can record
the original file that was renamed (its MD5 checksum, size, or what
not) or perhaps record the action in a history database or flag
file, and refuse to rename again if the file to be renamed is not
the original file.
Property: deps => HASH
This property specifies function's dependencies to various things. It
is a hash of dep types and values. Some dep types are special: "all",
"any", and "none".
deps => {
DEPTYPE => DEPVALUE,
...,
all => [
{DEPTYPE=>DEPVALUE, ...},
...,
},
any => [
{DEPTYPE => DEPVALUE, ...},
...,
],
none => [
{DEPTYPE => DEPVALUE, ...},
....,
],
}
A dependency can be of any type: another function, environment
variables, programs, OS software packages, etc. It is up to the
dependency checker library to make use of this information.
For the dependencies to be declared as satisfied, all of the clauses
must be satisfied.
Below is the list of defined dependency types. New dependency type may
be defined by an extension.
· dep: env => STR
Require that an environment variable exists and is true, where true
is in the Perl sense (not an empty string or "0"; " " and "0.0" are
both true). Example:
env => 'HTTPS'
· dep: prog => STR
Require that a program exists. If STR doesn't contain path
separator character '/' it will be searched in PATH. Windows
filesystem should also use Unix-style path, e.g. "C:/Program
Files/Foo/Bar.exe".
prog => 'rsync' # any rsync found on PATH
prog => '/bin/su' # won't accept any other su
· dep: code => CODE
Require that anonymous function returns a true value after called,
where the notion of true depends on the host language. Example in
Perl:
code => sub {$>} # i am not being run as root
Example in Ruby:
"code" => Proc.new { Process.euid > 0 } # i am not being run as root
· dep: tmp_dir => BOOL
If set to 1, specify that function requires temporary directory.
Caller should provide path to this using special argument
"-tmp_dir".
· dep: trash_dir => BOOL
If set to 1, specify that function requires trash directory. Trash
is not unlike a temporary directory. Caller should provide path to
trash directory using special argument "-trash_dir".
Trash directory can be provided, e.g. by transaction manager (see
Rinci::Transaction).
· dep: all => [DEPHASH, ...]
A "meta" type that allows several dependencies to be joined
together in a logical-AND fashion. All dependency hashes must be
satisfied. For example, to declare a dependency to several programs
and an environment variable:
all => [
{prog => 'rsync'},
{prog => 'tar'},
{env => 'FORCE'},
],
· dep: any => [DEPHASH, ...]
Like "all", but specify a logical-OR relationship. Any one of the
dependencies will suffice. For example, to specify requirement to
alternative Perl modules:
or => [
{perl_module => 'HTTP::Daemon'},
{perl_module => 'HTTP::Daemon::SSL'},
],
· dep: none => [DEPHASH, ...]
Specify that none of the dependencies must be satisfied for this
type to be satisfied. Example, to specify that the function not run
under SUDO or by root:
none => [
{env => 'SUDO_USER' },
{code => sub {$> != 0} },
],
Note that the above is not equivalent to below:
none => [
{env => 'SUDO_USER', code => sub {$> != 0} },
],
which means that if none or only one of 'env'/'code' is satisfied,
the whole dependency becomes a success (since it is negated by
'none'). Probably not what you want.
If you add a new language-specific dependency type, please prefix it
with the language code, e.g. "perl_module", "perl_func", "ruby_gem",
"python_egg". These dependency types have also been defined by some
existing tools: "deb" (dependency to a Debian package), "rpm"
(dependency to an RPM package), "js_url" (loading a remote JavaScript
script URL), "file" (existence of a), "perl_run_func" (running a Perl
subroutine and getting a successful enveloped result). Some of these
might be declared as part of the core dependency types in the future.
FAQ
What is the difference between "summary" or "description" in the Sah schema
and arg specification?
Example:
{
args => {
src => {
summary => "Source path",
description => "...",
schema => ["str*", {
summary => "...",
description => "...",
...
}],
...
},
dest => {
summary => "Target path",
description => "...",
schema => ["str*", {
summary => "...",
description => "...",
...
}],
...
},
...
},
}
As you can see, each argument has a "summary" and "description", but
the schema for each argument also has a "summary" and "description"
schema clauses. What is the difference and which should be put into
which?
The argument specification's "summary" (and "description") describe the
argument itself, in this example it says that "src" means "The source
path" and "dest" means "The target path". The argument schema's
"summary" (and "description") describe the data type and valid values.
In this example it could say, e.g., "a Unix-path string with a maximum
length of 255 characters". In fact, "src" and "dest" are probably of
the same type ("Unix path") and can share schema.
{
...
args => {
src => {
...
schema => "unix_path",
},
dest => {
...
schema => "unix_path",
},
...
},
}
What is the difference between setting req=>1 in the argument specification
and req=>1 in schema?
Example:
# Note: remember that in Sah, str* is equivalent to [str => {req=>1}]
args => {
a => { schema=>"str" },
b => { schema=>"str*" },
c => { req=>1, schema=>"str" },
d => { req=>1, schema=>"str*" },
}
In particular look at "b" and "c". "b" is not a required argument (no
req=>1 in the argument spec) but if it is specified, than it cannot be
undef/null (since the schema says [str=>{req=>1}], a.k.a "str*"). On
the other hand, "c" is a required argument (req=>1 in the argument
spec) but you can specify undef/null as the value. The following are
valid:
func(c=>undef, d=>1);
But the following are not:
func(b=>1, d=>1); # c is not specified
func(b=>undef, c=>1, d=>1); # b has undef value
func(b=>1, c=>1, d=>undef); # d has undef value
Should I add a new metadata property, or add a new feature name to the
"features" property, or add a new dependency type to the "deps"
property?
If your property describes a dependency to something, it should
definitely be a new dependency type. If your property only describes
what the function can do and does not include any wrapper code, then it
probably goes into "features". Otherwise, it should probably become a
new metadata property.
For example, if you want to declare that your function can only be run
under a certain moon phase (e.g. full moon), it should definitely go as
a new dependency type, so it becomes: deps => { moon_phase => 'full' }.
Another example, "reverse" is a feature name, because it just states
that if we pass "-reverse" => 1 special argument to a reversible
function, it can do a reverse operation. It doesn't include any wrapper
code, all functionality is realized by the function itself. On the
other hand, "timeout" is a metadata property because it involves adding
adding some wrapping code (a timeout mechanism, e.g. an eval() block
and alarm() in Perl).
SEE ALSO
Related specifications: Sah, HTTP/1.1 (RFC 2068)
Rinci
HOMEPAGE
Please visit the project's homepage at
<https://metacpan.org/release/Rinci>.
SOURCE
Source repository is at <https://github.com/sharyanto/perl-Rinci>.
BUGS
Please report any bugs or feature requests on the bugtracker website
<https://rt.cpan.org/Public/Dist/Display.html?Name=Rinci>
When submitting a bug or request, please include a test-file or a patch
to an existing test-file that illustrates the bug or desired feature.
AUTHOR
Steven Haryanto <stevenharyanto@gmail.com>
COPYRIGHT AND LICENSE
This software is copyright (c) 2013 by Steven Haryanto.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
perl v5.18.1 2013-12-25 Rinci::function(3pm)
