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Data Type Declarations and Restrictions

Starting in Qore 0.8.0, it is possible to restrict variables, class members, and function and method parameters to certain data types. This allows programmers to write safer code, as many more errors can be caught at parse time that would otherwise be caught at run time. Furthermore, providing type information to the parser allows Qore to implement performance optimizations by performing lookups and resolutions once at parse time rather than every time a variable or class member is accessed at run time.

When types are declared in a parameter list, functions and methods can be overloaded as well.

The types in the following table can be used as well as any class name or `'*classname'` (i.e. an asterix followed by the class name), meaning either the given class or NOTHING (no value).

Data Type Declaration Names

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
int | Integer | Integer | Restricts values Integer values
float | Float or Integer | Float | Restricts values to Float values
number | Number, Float, or Integer | Number | Restricts values to Number values
bool | Boolean | Boolean | Restricts values to Boolean values
string | String | String | Restricts values to String values
date | Date | Date | Restricts values to Date values; values may be either absolute or relative
binary | Binary | Binary | Restricts values to Binary values
hash | Hash | Hash | Restricts values to Hash values
list | List | List | Restricts values to List values
object | Object | Object | Restricts values to Object values
<classname> | Object | Object | Restricts values to objects of the specific class given; either the class name can be given (ex: Mutex or a qualified path to the class: Qore::Thread::Mutex)
null | NULL | NULL | Restricts values to Qore's NULL type; this type has few (if any) practical applications and has been included for completeness' sake
nothing | NOTHING | NOTHING | Restricts values to Qore's NOTHING type; this type is mostly useful for declaring that a function or method returns no value
timeout | Integer, Date | Integer | Accepts Integer, Date and converts dates to an integer value representing milliseconds and returns the integer; incoming integers are assumed to represent milliseconds
softint | Integer, Float, Number, Boolean, String, NULL | Integer | Accepts Integer, Float, Boolean, String, NULL and converts non-integer values to an integer and returns the integer
softfloat | Integer, Float, Number, Boolean, String, NULL | Float | Accepts Integer, Float, Boolean, String, NULL and converts non-float values to a float and returns the new value
softnumber | Integer, Float, Number, Boolean, String, NULL | Float | Accepts Integer, Float, Boolean, String, NULL and converts non-float values to a float and returns the new value
softbool | Integer, Float, Number, Boolean, String, NULL | Boolean | Accepts Integer, Float, Boolean, String, NULL and converts non-boolean values to a boolean and returns the new value
softstring | Integer, Float, Number, Boolean, String, NULL | String | Accepts Integer, Float, Boolean, String, NULL and converts non-string values to a string and returns the new value
softdate | Integer, Float, Number, Boolean, String, Date, NULL | Date | Accepts Integer, Float, Boolean, String, Date, and NULL and converts non-date values to a date and returns the new value
softlist | all types | List | Accepts all types; NOTHING is returned as an empty list; a list is returned unchanged, and any other type is returned as the first element of a new list
data | String or Binary | same as received | Restricts input to String and Binary and returns the same type
code | Closures, Call References | same as received | Restricts values to closures and call references
reference | References | the type the reference points to | Restricts values to references to lvalues
*int | Integer or NOTHING | same as received | Restricts values to Qore's Integer or NOTHING types
*float | Float or NOTHING | same as received | Restricts values to Qore's Float or NOTHING types
*bool | Boolean or NOTHING | same as received | Restricts values to Qore's Boolean or NOTHING types
*string | String or NOTHING | same as received | Restricts values to Qore's String or NOTHING types
*date | Date or NOTHING | same as received | Restricts values to Qore's Date or NOTHING type; values may be either absolute or relative date/time values
*binary | Binary or NOTHING | same as received | Restricts values to Qore's Binary or NOTHING types
*hash | Hash or NOTHING | same as received | Restricts values to Qore's Hash or NOTHING types
*list | List or NOTHING | same as received | Accepts either a List or NOTHING
*object | Object or NOTHING | same as received | Accepts either an Object or NOTHING
*<classname> | Object of the given class or NOTHING | same as received | Restricts values to objects of the specific class given or NOTHING; either the class name can be given (ex: *Mutex or a qualified path to the class: *Qore::Thread::Mutex)
*data | String, Binary, or NOTHING | same as received | Restricts input to String, Binary, or NOTHING and returns the same type
*code | Closures, Call References, NOTHING | same as received | Restricts values to closures, call references and NOTHING
*timeout | Integer, Date or NOTHING | Integer or NOTHING | Accepts Integer, Date and converts dates to an integer value representing milliseconds and returns the integer; incoming integers are assumed to represent milliseconds. If no value is passed, then NOTHING is returned
*reference | References or NOTHING | the type the reference points to | Restricts values to references to lvalues and NOTHING
*softint | Integer, Float, Number, Boolean, String, NULL or NOTHING | Integer or NOTHING | Accepts Integer, Float, Number, Boolean, String, NULL and converts non-integer values to an integer and returns the integer. If no value is passed, then NOTHING is returned
*softfloat | Integer, Float, Number, Boolean, String, NULL or NOTHING | Float or NOTHING | Accepts Integer, Float, Number, Boolean, String, NULL and converts non-float values to a float and returns the new value. If no value is passed, then NOTHING is returned
*softnumber | Integer, Float, Number, Boolean, String, NULL or NOTHING | Number or NOTHING | Accepts Integer, Float, Number, Boolean, String, NULL and converts non-number values to a number and returns the new value. If no value is passed, then NOTHING is returned
*softbool | Integer, Float, Number, Boolean, String, NULL or NOTHING | Boolean or NOTHING | Accepts Integer, Float, Number, Boolean, String, NULL and converts non-boolean values to a boolean and returns the new value. If no value is passed, then NOTHING is returned
*softstring | Integer, Float, Number, Boolean, String, NULL or NOTHING | String or NOTHING | Accepts Integer, Float, Number, Boolean, String, NULL and converts non-string values to a string and returns the new value. If no value is passed, then NOTHING is returned
*softdate | Integer, Float, Number, Boolean, String, Date, NULL or NOTHING | Date or NOTHING | Accepts Integer, Float, Number, Boolean, String, Date, and NULL and converts non-date values to a date and returns the new value. If no value is passed, then NOTHING is returned
*softlist | all types | List or NOTHING | Accepts all types; NOTHING and list values are returned as the same value; any other type is returned as the first element of a new list
any | any | same as received | Provides no restrictions on the type of value it receives and returns the same value

# int

int Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`int` | Integer | Integer | Restricts values to Qore's Integer type

Example
  int sub foo(int $i) {
  return $i;
  }

# float

float Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`float` | Float or Integer | Float | Restricts values to Qore's Float type

Example
  float sub foo(float $f = M_PI) {
  return $f;
  }

# number

number Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`number` | Number, Float, or Integer | Number | Restricts values to Qore's Number type

Example
  number sub foo(number $n = 2.35e40) {
  return $n;
  }

Since
  Qore 0.8.6 introduced the number type

# bool

bool Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`bool` | Boolean | Boolean | Restricts values to Qore's Boolean type

Example
  bool sub foo(bool $b) {
  return $b;
  }

# string

string Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`string` | String | String | Restricts values to Qore's String type

Example
  string sub foo(string $str = "bar") {
  return $str;
  }

# date

date Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`date` | Date | Date | Restricts values to Qore's Date type; date/time values can be either absolute or relative

Example
  date sub foo(date $d = now_us()) {
  return $d;
  }

# binary

binary Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`binary` | Binary | Binary | Restricts values to Qore's Binary type

Example
  binary sub foo(binary $b) {
  return $b;
  }

# hash

hash Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`hash` | Hash | Hash | Restricts values to Qore's Hash type

Example
  hash sub foo(hash $h = ("foo": "bar", "x": 2)) {
  return $h;
  }

# list

list Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`list` | List | List | Restricts values to Qore's List type

Example
  list sub foo(list $l = "foo", "bar")) {
  return $l;
  }

# object

object Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`object` | Object | Object | Restricts values to Qore's Object type; note that any class name can also be used as a type restriction directly

Example
  object sub foo(object $o = new Mutex()) {
  return $o;
  }

# <classname>

<classname> Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
any class name | Object of the particular class given | Object of the particular class given | Restricts values to objects of the particular class given; subclasses are also accepted

Example
  Mutex sub foo(Qore::Thread::Mutex $m = new Mutex()) {
  return $m;
  }

# null

null Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`null` | NULL | NULL | Restricts values to Qore's NULL type; this type has few (if any) practical applications and has been included for completeness' sake

Example
  # I don't know if this type has any useful/practical applications...
  my null $n = NULL;

# nothing

nothing Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`nothing` | NOTHING | NOTHING | Restricts values to Qore's NOTHING type; this type is mostly useful for declaring that a function or method returns no value

Example
  nothing sub bar() {
  printf("foo\n");
  }

# timeout

timeout Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`timeout` | Integer, Date | Integer | Accepts Integer, Date values and converts dates to an integer value representing milliseconds and returns the integer; incoming integers are assumed to represent milliseconds

Example
  timeout sub foo(timeout $to = 1250ms) {
  return $to;
  }

# softint

softint Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`softint` | Integer, Float, Number, Boolean, String, NULL | Integer | Accepts Integer, Float, Number, Boolean, String, and NULL values and converts non-integer values to an integer and returns the integer

Example
  softint sub foo(softint $i = "1000") {
  # note that "200" will be converted to an integer on return
  return $i > 500 ? "200" : $i;
  }

# softfloat

softfloat Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`softfloat` | Integer, Float, Number, Boolean, String, NULL | Float | Accepts Integer, Float, Number, Boolean, String, and NULL values and converts non-float values to a float and returns the float

Example
  softfloat sub foo(softfloat $f = "1000") {
  # note that "200" will be converted to a float on return
  return $f > 500.0 ? "200" : $f;
  }

# softnumber

softnumber Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`softnumber` | Integer, Float, Number, Boolean, String, NULL | Float | Accepts Integer, Float, Number, Boolean, String, and NULL values and converts non-number values to a number and returns the number

Example
  softnumber sub foo(softnumber $n = "1000") {
  # note that "200" will be converted to a number on return
  return $n > 500.0n ? "200" : $n;
  }

Since
  Qore 0.8.6 introduced the softnumber type

# softbool

softbool Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`softbool` | Integer, Float, Number, Boolean, String, NULL | Boolean | Accepts Integer, Float, Number, Boolean, String, and NULL values and converts non-boolean values to a boolean and returns the boolean

Example
  my softbool $b = "0.5";

# softstring

softstring Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`softstring` | Integer, Float, Number, Boolean, String, NULL | String | Accepts Integer, Float, Number, Boolean, String, and NULL values and converts non-string values to a string and returns the string

Example
  my softstring $str = 200;

# softdate

softdate Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`softdate` | Integer, Float, Number, Boolean, String, Date, NULL | Date | Accepts Integer, Float, Number, Boolean, String, Date, and NULL values and converts non-date values to a date and returns the date

Example
  my softdate $d = "2001-10-10T20:00:05 +04:00";

# softlist

softlist Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`softlist` | all data types | List | Accepts all data types; NOTHING is returned as an empty list; a list is returned unchanged, and any other type is returned as the first element of a new list

Example
  softlist sub foo(softlist $l) {
  foreach my any $element in (\$l) {
  }
  return $l;
  }

Since
  Qore 0.8.3 introduced the softlist type

# data

data Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`data` | String or Binary | same as received | Restricts values to String and Binary

Example
  data sub foo(data $d) {
  return $d;
  }

# code

code Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`code` | Closures, Call References | same as received | Restricts values to Closures and Call References

Example
  sub foo(code $c) {
  $c();
  }

Note
  that also `"closure"` and `"callref"` are accepted as synonyms for `"code"` (they are not more specific than `"code"` but rather provide identical type restrictions)

# reference

reference Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`reference` | References | the type the reference points to | Requires a reference to an lvalue to be assigned

Example
  sub foo(reference $f) {
  $f = 10;
  }
  my int $i;
  foo(\$i);

# *int

*int Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*int` | Integer or NOTHING | same as received | Restricts values to Integer and NOTHING

Example
  *int sub foo(*int $i) {
  return $i;
  }

# *float

*float Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*float` | Float or NOTHING | same as received | Restricts values to Float and NOTHING

Example
  *float sub foo(*float $f) {
  return $f;
  }

# *number

*number Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*number` | Number or NOTHING | same as received | Restricts values to Number and NOTHING

Example
  *number sub foo(*number $n) {
  return $n;
  }

Since
  Qore 0.8.6 introduced the *number type

# *bool

*bool Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*bool` | Boolean or NOTHING | same as received | Restricts values to Boolean and NOTHING

Example
  *bool sub foo(*bool $b) {
  return $b;
  }

# *string

*string Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*string` | String or NOTHING | same as received | Restricts values to String and NOTHING

Example
  *string sub foo(*string $str) {
  return $str;
  }

# *date

*date Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*date` | Date or NOTHING | same as received | Restricts values to Date and NOTHING

Example
  *date sub foo(*date $str) {
  return $str;
  }

# *binary

*binary Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*binary` | Binary or NOTHING | same as received | Restricts values to Binary and NOTHING

Example
  *binary sub foo(*binary $b) {
  return $b;
  }

# *hash

*hash Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*hash` | Hash or NOTHING | same as received | Restricts values to Hash and NOTHING

Example
  *hash sub foo(*hash $h) {
  return $h;
  }

# *list

*list Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*list` | List or NOTHING | same as received | Restricts values to List and NOTHING

Example
  *list sub foo(*list $l) {
  return $l;
  }

# *object

*list Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*list` | Object or NOTHING | same as received | Restricts values to Object and NOTHING

Example
  *object sub foo(*object $obj) {
  return $obj;
  }

# *<classname>

*<classname> Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*`any class name | Object of the particular class given or NOTHING | same as received | Restricts values to objects of the particular class given or NOTHING; subclasses are also accepted

Example
  sub foo(*Mutex $m) {
  }

# *date

*data Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*data` | String, Binary, or NOTHING | same as received | Restricts values to String, Binary, and NOTHING

Example
  sub foo(*data $d) {
  }

# *code

*code Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*code` | Closures, Call References, or NOTHING | same as received | Restricts values to Closures, Call References, and NOTHING

Example
  sub foo(*code $c) {
  }

# *timeout

*timeout Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*timeout` | Integer, Date, or NOTHING | Integer or NOTHING | converts dates to an integer value representing milliseconds and returns the integer; incoming integers are assumed to represent milliseconds; also accepts NOTHING and returns NOTHING

Example
  sub foo(*timeout $c) {
  }

# *reference

reference Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`reference` | References or NOTHING | the type the reference points to | Requires a reference to an lvalue to be assigned or NOTHING

Example
  sub foo(*reference $f) {
  $f = 10;
  }
  my int $i;
  foo(\$i);

# *softint

*softint Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*softint` | Integer, Float, Number, Boolean, String, NULL, NOTHING | Integer or NOTHING | Accepts Integer, Float, Number, Boolean, String, and NULL values and converts non-integer values to an integer and returns the integer; also accepts NOTHING and returns NOTHING

Example
  sub foo(*softint $i) {
  }

# *softfloat

*softfloat Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*softfloat` | Integer, Float, Number, Boolean, String, NULL, NOTHING | Float or NOTHING | Accepts Integer, Float, Number, Boolean, String, and NULL values and converts non-float values to a float and returns the float; also accepts NOTHING and returns NOTHING

Example
  sub foo(*softfloat $f) {
  }

# *softnumber

*softnumber Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*softnumber` | Integer, Float, Number, Boolean, String, NULL, NOTHING | Number or NOTHING | Accepts Integer, Float, Number, Boolean, String, and NULL values and converts non-number values to a number and returns the number; also accepts NOTHING and returns NOTHING

Example
  sub foo(*softnumber $n) {
  }

Since
  Qore 0.8.6 introduced the *softnumber type

# *softbool

*softbool Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*softbool` | Integer, Float, Number, Boolean, String, NULL, NOTHING | Boolean or NOTHING | Accepts Integer, Float, Number, Boolean, String, and NULL values and converts non-boolean values to a boolean and returns the boolean; also accepts NOTHING and returns NOTHING

Example
  sub foo(*softbool $b) {
  }

# *softstring

*softstring Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*softstring` | Integer, Float, Number, Boolean, String, NULL, NOTHING | String or NOTHING | Accepts Integer, Float, Number, Boolean, String, and NULL values and converts non-string values to a string and returns the string; also accepts NOTHING and returns NOTHING

Example
  sub foo(*softstring $str) {
  }

# *softdate

*softdate Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*softdate` | Integer, Float, Number, Boolean, String, Date, NULL, NOTHING | String or NOTHING | Accepts Integer, Float, Number, Boolean, String, Date, and NULL values and converts non-date values to a date and returns the date; also accepts NOTHING and returns NOTHING

Example
  sub foo(*softdate $d) {
  }

# *softlist

*softlist Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`*softlist` | all data types | List or NOTHING | Accepts all data types; NOTHING is returned as NOTHING directly; a list is returned unchanged, and any other type is returned as the first element of a new list

Example
  my *softlist $d = $v;

Since
  Qore 0.8.3 introduced the *softlist type

# any

any Type Restriction

Name | Accepts Qore Type(s) | Returns Qore Type(s) | Description
`any` | all data types | all data types | Accepts all data types and returns the same data type

Example
  my any $v = $bar;

Note
  Complex types (hash of lists, reference to string, etc) are currently not possible to declare but support may be added in future versions of Qore for this.