<value> Class Reference

Methods in this pseudo-class are available to be executed on any value type (even NOTHING); this is the root class for all pseudo-classes. More...

#include <Pseudo_QC_All.dox.h>

Inheritance diagram for Qore::<value>:

Public Member Methods
bool	callp ()
	Returns False; this method is reimplemented in other types and will return True if the given expression is a callable value (ie closures or call references)
bool	complexType ()
	returns True if the value has a complex type, False if not
bool	empty ()
	Returns True; this method will be reimplemented in container types where it may return False.
string	fullType (__7_ bool with_namespaces)
	returns the full type name which differs from the simple type name in case of complex types and objects
bool	intp ()
	Returns False; this method is reimplemented in other types and will return True if the given expression can be converted to an integer.
AbstractIterator	iterator ()
	Returns an iterator object for the value; the default iterator object returned is SingleValueIterator.
int	lsize ()
	Returns 1; the return value of this method should give the list size of the value, which is normally 1 for non-lists (except for NOTHING where the size will be 0) and the number of the elements in the list for lists; this method will be reimplemented in other types where it may return other values.
int	size ()
	Returns zero; this method will be reimplemented in container types where it may return a non-zero value.
bool	sizep ()
	Returns True if the type can return a non-zero size (True for containers including binary objects and strings, False for everything else)
bool	strp ()
	Returns False; this method is reimplemented in other types and will return True if the given expression can be converted to a string.
bool	toBool ()
	Returns the boolean representation of the value; the default is False.
float	toFloat ()
	Returns the floating-point representation of the value; the default is 0.0.
int	toInt ()
	Returns the integer representation of the value; the default is 0.
number	toNumber ()
	Returns the arbitrary-precision numeric representation of the value; the default is 0.
string	toString (__7_ string encoding)
	Returns the string representation of the value; the default is an empty string.
string	type ()
	Returns the string type for the value.
int	typeCode ()
	Returns the type code for the value.
bool	val ()
	Returns False; this method is reimplemented in other types and will return True if the given expression has a non-empty value.

Detailed Description

Methods in this pseudo-class are available to be executed on any value type (even NOTHING); this is the root class for all pseudo-classes.

Member Function Documentation

callp()

bool <value>::callp

(

)

Returns False; this method is reimplemented in other types and will return True if the given expression is a callable value (ie closures or call references)

Returns

False; this method is reimplemented in other types and will return True if the given expression is a callable value (ie closures or call references)

Code Flags:

CONSTANT

Example:

if (n.callp())
    printf("the reuslt of calling the value: %y\n", n());

complexType()

bool <value>::complexType

(

)

returns True if the value has a complex type, False if not

Code Flags:

CONSTANT

Example:

bool b = n.complexType();

Returns

True if the value has a complex type, False if not; if this pseudo-method returns True, then the return value of <value>::fullType() will differ from that of <value>::type()

Complex types are:

• Type-Safe Hash Type
• Hash With Declared Value Type
• List With Declared Value Type
• objects

See also

• <value>::fullType()
• <value>::type()
• <value>::typeCode()

Since

Qore 0.8.13

empty()

bool <value>::empty

(

)

Returns True; this method will be reimplemented in container types where it may return False.

This pseudo-method will return False in all non-container types; use <value>::val() to check if a generic expression that might not be a container type has a value instead.

Returns

True; this method will be reimplemented in container types where it may return False

Code Flags:

CONSTANT

Example:

int i = 100;
if (i.empty())
    printf("%y: is empty (probably because it's a value of type %y)\n", i, i.type());

See also

<value>::val()

fullType()

string <value>::fullType

(

__7_ bool

with_namespaces

)

returns the full type name which differs from the simple type name in case of complex types and objects

Code Flags:

CONSTANT

Example:

hash <string, int> h();
# returns "hash<string, int>"
string str = n.fullType();
Mutex m();
# returns "object<Mutex>"
str = m.fullType();

Returns

the full type name which differs from the simple type name in case of complex types and objects; for simple types the return value is the same as for <value>::type()

Complex types are:

• hashdecl hashes: the complex type description is returned (ex: "hash<MyHash>")
• complex hashes: the complex type description is returned (ex: "hash<string, int>")
• complex lists: the complex type description is returned (ex: "list<int>")
• objects: the complex type description is returned (ex: "object<MyClass>"; see Class-Specific Type Declaration)

See also

• <value>::complexType()
• <value>::type()
• <value>::fullType()

Since

• Qore 0.8.13
• Qore 1.0 added the with_namespaces argument

intp()

bool <value>::intp

(

)

Returns False; this method is reimplemented in other types and will return True if the given expression can be converted to an integer.

Returns

False; this method is reimplemented in other types and will return True if the given expression can be converted to an integer

Code Flags:

CONSTANT

Example:

if (n.intp())
    printf("%y: can be converted to an integer: %d\n", n, int(n));

See also

<string>::intp() for an example of an implementation of this method where the result depends on the value and not the type

iterator()

AbstractIterator <value>::iterator

(

)

Returns an iterator object for the value; the default iterator object returned is SingleValueIterator.

Returns

an iterator object for the value; the default iterator object returned is SingleValueIterator

Code Flags:

CONSTANT

Example:

map printf("+ %y\n", $1), v.iterator();

Since

Qore 0.8.6

lsize()

int <value>::lsize

(

)

Returns 1; the return value of this method should give the list size of the value, which is normally 1 for non-lists (except for NOTHING where the size will be 0) and the number of the elements in the list for lists; this method will be reimplemented in other types where it may return other values.

Returns

1; the return value of this method should give the list size of the value, which is normally 1 for non-lists (except for NOTHING where the size will be 0) and the number of the elements in the list for lists; this method will be reimplemented in other types where it may return other values

Code Flags:

CONSTANT

Example:

printf("iterating %d element%s\n", val.lsize(), val.lsize() == 1 ? "" : "s");
foreach any element in (val) {
    do_something(element);
}

size()

int <value>::size

(

)

Returns zero; this method will be reimplemented in container types where it may return a non-zero value.

This pseudo-method will return 0 in all non-container types; use <value>::val() to check if a generic expression that might not be a container type has a value instead.

Returns

zero; this method will be reimplemented in container types where it may return a non-zero value

Code Flags:

CONSTANT

Example:

int i = 100;
if (!i.size())
    printf("%y: has size 0 (probably because it's a value of type %y)\n", i, i.type());

See also

• <value>::size()
• <value>::val()

sizep()

bool <value>::sizep

(

)

Returns True if the type can return a non-zero size (True for containers including binary objects and strings, False for everything else)

Code Flags:

CONSTANT

Returns

True if the type can return a non-zero size (True for containers including binary objects and strings, False for everything else)

See also

<value>::size()

Since

Qore 0.8.9

strp()

bool <value>::strp

(

)

Returns False; this method is reimplemented in other types and will return True if the given expression can be converted to a string.

Returns

False; this method is reimplemented in other types and will return True if the given expression can be converted to a string

Code Flags:

CONSTANT

Example:

if (n.strp())
    printf("%y: can be converted to a string: '%s'\n", n, string(n));

toBool()

bool <value>::toBool

(

)

Returns the boolean representation of the value; the default is False.

Code Flags:

CONSTANT

Returns

the boolean representation of the value; the default is False

Note

if <value>::intp() returns True, then the value can also be converted to a boolean value

Since

Qore 0.8.6

toFloat()

float <value>::toFloat

(

)

Returns the floating-point representation of the value; the default is 0.0.

Code Flags:

CONSTANT

Returns

the floating-point representation of the value; the default is 0.0

Note

if <value>::intp() returns True, then the value can also be converted to a floating-point value

Since

Qore 0.8.6

toInt()

int <value>::toInt

(

)

Returns the integer representation of the value; the default is 0.

Code Flags:

CONSTANT

Use <value>::intp() to determine if the current value can be converted to an integer

Returns

the integer representation of the value; the default is 0

Since

Qore 0.8.6

toNumber()

number <value>::toNumber

(

)

Returns the arbitrary-precision numeric representation of the value; the default is 0.

Code Flags:

CONSTANT

Returns

the integer representation of the value; the default is 0

Note

if <value>::intp() returns True, then the value can also be converted to an arbitrary-precision numeric value

Since

Qore 0.8.8

toString()

string <value>::toString

(

__7_ string

encoding

)

Returns the string representation of the value; the default is an empty string.

Code Flags:

CONSTANT

Use <value>::strp() to determine if the current value can be converted to a string

Returns

the string representation of the value; the default is an empty string

Note

check pseudo-classes for each type for other variants of this method; some may take arguments to affect the output format return false;

Since

Qore 0.8.6

type()

string <value>::type

(

)

Returns the string type for the value.

Code Flags:

CONSTANT

Example:

string t = n.type();

Returns

the string type for the value; see String Type Constants for possible return values for each type

Note

It is faster and more efficient to use <value>::typeCode() for comparing data types

See also

• <value>::typeCode()
• <value>::fullType()
• <value>::complexType()

typeCode()

int <value>::typeCode

(

)

Returns the type code for the value.

Code Flags:

CONSTANT

Example:

switch (v.typeCode()) {
    case NT_INT:
        printf("%y: is an integer\n", v);
        break;
 
    case NT_DATE:
        printf("%y: is a date\n", v);
        break;
 
    default:
        printf("%y: is something else entirely\n", v);
        break;
}

This method is recommended over <value>::type() or the type(any) or typename(any) functions for comparing data types as it is much faster and more efficient than the other alternatives (which work with string values instead of integer codes).

Returns

the type code for the value; see Type Code Constants for possible return values for each type

See also

• <value>::type()
• <value>::fullType()
• <value>::complexType()

val()

bool <value>::val

(

)

Returns False; this method is reimplemented in other types and will return True if the given expression has a non-empty value.

Returns

False; this method is reimplemented in other types and will return True if the given expression has a non-empty value

Code Flags:

CONSTANT

Example:

if (n.val())
    printf("%y: has a non-empty value\n", n);

Rules:

Type	Rule
int, float, number	False if zero, True if non-zero
string	False if empty, True if not empty
list	False if empty, True if not empty
hash	False if empty, True if not empty
object	always True with a valid object
code	always True
NOTHING	always False
NULL	always False

Example Values:

Example	Result
0.val()	False
1.val()	True
"".val()	False (empty string)
"0".val()	True
"string".val()	True
().val()	False (empty list)
(0,).val()	True
{}.val()	False (empty hash)
("a":0).val()	True
NOTHING.val()	False
NULL.val()	False

Note

• Use Exists Operator (exists) to tell if an expression has a value or not
• This pseudo-method can be used to mimic perl's boolean evaluation when %strict-bool-eval is enabled; the return value of this method is the same as that of any value except "0" when evaluated in a boolean context when %perl-bool-eval is enabled (the default); note that "0".val() returns True while boolean("0") returns False in all cases.

See also

• %perl-bool-eval
• %strict-bool-eval