Expression function for use within a QgsExpressionContextScope. More...

#include <qgsexpressioncontext.h>

Inheritance diagram for QgsScopedExpressionFunction:

Public Member Functions
	QgsScopedExpressionFunction (const QString &fnname, int params, const QString &group, const QString &helpText=QString(), bool usesGeometry=false, const QStringList &referencedColumns=QStringList(), bool lazyEval=false, bool handlesNull=false, bool isContextual=true)

virtual	~QgsScopedExpressionFunction ()

virtual QgsScopedExpressionFunction *	clone () const =0
	Returns a clone of the function. More...

virtual QVariant	func (const QVariantList &values, const QgsExpressionContext context, QgsExpression parent) override=0
	Returns result of evaluating the function. More...

Public Member Functions inherited from QgsExpression::Function
	Function (const QString &fnname, int params, const QString &group, const QString &helpText=QString(), bool usesGeometry=false, const QStringList &referencedColumns=QStringList(), bool lazyEval=false, bool handlesNull=false, bool isContextual=false)
	Constructor for function which uses unnamed parameters. More...

	Function (const QString &fnname, int params, const QStringList &groups, const QString &helpText=QString(), bool usesGeometry=false, const QStringList &referencedColumns=QStringList(), bool lazyEval=false, bool handlesNull=false, bool isContextual=false)
	Constructor for function which uses unnamed parameters and group list. More...

	Function (const QString &fnname, const ParameterList &params, const QString &group, const QString &helpText=QString(), bool usesGeometry=false, const QStringList &referencedColumns=QStringList(), bool lazyEval=false, bool handlesNull=false, bool isContextual=false)
	Constructor for function which uses named parameter list. More...

	Function (const QString &fnname, const ParameterList &params, const QStringList &groups, const QString &helpText=QString(), bool usesGeometry=false, const QStringList &referencedColumns=QStringList(), bool lazyEval=false, bool handlesNull=false, bool isContextual=false)
	Constructor for function which uses named parameter list and group list. More...

virtual	~Function ()

virtual QStringList	aliases () const
	Returns a list of possible aliases for the function. More...

virtual Q_DECL_DEPRECATED QVariant	func (const QVariantList &, const QgsFeature , QgsExpression )

QString	group () const
	Returns the first group which the function belongs to. More...

QStringList	groups () const
	Returns a list of the groups the function belongs to. More...

virtual bool	handlesNull () const

const QString	helptext () const
	The help text for the function. More...

bool	isContextual () const
	Returns whether the function is only available if provided by a QgsExpressionContext object. More...

virtual bool	isDeprecated () const
	Returns true if the function is deprecated and should not be presented as a valid option to users in expression builders. More...

bool	lazyEval () const
	True if this function should use lazy evaluation. More...

int	minParams () const
	The mininum number of parameters this function takes. More...

QString	name () const
	The name of the function. More...

bool	operator== (const Function &other) const

const ParameterList &	parameters () const
	Returns the list of named parameters for the function, if set. More...

int	params () const
	The number of parameters this function takes. More...

virtual QStringList	referencedColumns () const

bool	usesgeometry () const
	Does this function use a geometry object. More...

Detailed Description

Expression function for use within a QgsExpressionContextScope.

This differs from a standard QgsExpression::Function in that it requires an implemented clone() method.

Note: added in QGIS 2.12

Definition at line 41 of file qgsexpressioncontext.h.

Constructor & Destructor Documentation

◆ QgsScopedExpressionFunction()

QgsScopedExpressionFunction::QgsScopedExpressionFunction	(	const QString &	fnname,
		int	params,
		const QString &	group,
		const QString &	helpText = `QString()`,
		bool	usesGeometry = `false`,
		const QStringList &	referencedColumns = `QStringList()`,
		bool	lazyEval = `false`,
		bool	handlesNull = `false`,
		bool	isContextual = `true`
	)

inline

Definition at line 44 of file qgsexpressioncontext.h.

◆ ~QgsScopedExpressionFunction()

virtual QgsScopedExpressionFunction::~QgsScopedExpressionFunction ( )

inlinevirtual

Definition at line 56 of file qgsexpressioncontext.h.

Member Function Documentation

◆ clone()

virtual QgsScopedExpressionFunction* QgsScopedExpressionFunction::clone ( ) const

pure virtual

Returns a clone of the function.

◆ func()

virtual QVariant QgsScopedExpressionFunction::func	(	const QVariantList &	values,
		const QgsExpressionContext *	context,
		QgsExpression *	parent
	)

overridepure virtual

Returns result of evaluating the function.

Parameters

values	list of values passed to the function
context	context expression is being evaluated against
parent	parent expression

Returns: result of function

Note: named funcV2 in Python bindings. Will be renamed to func to replace deprecated method in QGIS 3.0.

Reimplemented from QgsExpression::Function.

The documentation for this class was generated from the following file:

/tmp/buildd/qgis-2.18.21+99unstable/src/core/qgsexpressioncontext.h