NAME¶
Rinci::function - Metadata for your functions/methods
VERSION¶
This document describes version 1.1.52 of Rinci::function (from Perl
distribution Rinci), released on 2014-06-29.
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).
- •
- 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, or a hash containing these keys:
"completion" (array, list of possible candidates) and extra keys for
formatting hints e.g. "is_path" (bool, whether the list of
completion is path-like, meaning it can be traversed/dug to multiple levels)
"path_sep" (string, path separator character), "type"
(string, either "filename", "env", or other types). 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: pkg => STR
Specify dependency on a Riap package. STR must be a valid Riap package URI
string. Checker can check that requesting "info" on this URI
succeeds and the type is indeed "package". Example:
pkg => '/Foo/'
- •
- dep: func => STR
Specify dependency on a Riap function. STR must be a valid Riap function URI
string. Checker can check that requesting "info" on this URI
succeeds and the type is indeed "package". Example:
pkg => '/Foo/somefunc'
pkg => 'http://gudangapi.com/ga/list_ubuntu_releases'
- •
- 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
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) 2014 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.