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Fix qgsfunction decorator args handling
This commit is contained in:
Yoann Quenach de Quivillic
parent
d3d8ba1a30
commit
947931ad2b
@ -1,5 +1,3 @@
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# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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qgsfunction.py
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@ -26,30 +24,31 @@ from qgis.PyQt.QtCore import QCoreApplication
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from qgis._core import QgsExpressionFunction, QgsExpression, QgsMessageLog, QgsFeatureRequest, Qgis
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def register_function(function, arg_count, group, usesgeometry=False,
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referenced_columns=[QgsFeatureRequest.ALL_ATTRIBUTES], handlesnull=False, **kwargs):
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def register_function(
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function,
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group,
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usesgeometry=False,
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referenced_columns=[QgsFeatureRequest.ALL_ATTRIBUTES],
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handlesnull=False,
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**kwargs,
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):
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"""
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Register a Python function to be used as a expression function.
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Functions should take (values, feature, parent) as args:
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The function signature may contains special parameters:
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- context: the QgsExpressionContext-related to the current evaluation
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- feature: the QgsFeature-related to the current evaluation
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- parent: the QgsExpressionFunction parent
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Example:
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def myfunc(values, feature, parent):
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pass
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If those parameters are present in the function signature, they will be automatically passed to the function,
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without the need to specify them in the expression.
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They can also shortcut naming feature and parent args by using *args
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if they are not needed in the function.
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Example:
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def myfunc(values, *args):
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pass
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If the only other parameter in the signature is called "values", parameters will be passed as a list.
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Otherwise, parameters will be expanded in the parameter list.
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Functions should return a value compatible with QVariant
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Eval errors can be raised using parent.setEvalErrorString("Error message")
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:param function:
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:param arg_count:
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:param group:
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:param usesgeometry:
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:param handlesnull: Needs to be set to True if this function does not always return NULL if any parameter is NULL. Default False.
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@ -57,12 +56,20 @@ def register_function(function, arg_count, group, usesgeometry=False,
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"""
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class QgsPyExpressionFunction(QgsExpressionFunction):
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def __init__(self, func, name, args, group, helptext='', usesGeometry=True,
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referencedColumns=QgsFeatureRequest.ALL_ATTRIBUTES, expandargs=False, handlesNull=False):
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QgsExpressionFunction.__init__(self, name, args, group, helptext)
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def __init__(
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self,
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func,
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name,
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group,
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helptext="",
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usesGeometry=True,
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referencedColumns=QgsFeatureRequest.ALL_ATTRIBUTES,
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handlesNull=False,
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paramsAsList=False,
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):
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QgsExpressionFunction.__init__(self, name, -1, group, helptext)
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self.function = func
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self.expandargs = expandargs
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self.params_as_list = paramsAsList
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self.uses_geometry = usesGeometry
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self.referenced_columns = referencedColumns
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self.handles_null = handlesNull
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@ -71,21 +78,26 @@ def register_function(function, arg_count, group, usesgeometry=False,
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feature = None
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if context:
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feature = context.feature()
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try:
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if self.expandargs:
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values.append(feature)
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values.append(parent)
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if inspect.getfullargspec(self.function).args[-1] == 'context':
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values.append(context)
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return self.function(*values)
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else:
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if inspect.getfullargspec(self.function).args[-1] == 'context':
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self.function(values, feature, parent, context)
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return self.function(values, feature, parent)
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parameters = inspect.signature(self.function).parameters
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kwvalues = {}
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# Handle special parameters
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# those will not be inserted in the parameter list
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# if they are present in the function signature
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if "context" in parameters:
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kwvalues["context"] = context
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if "feature" in parameters:
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kwvalues["feature"] = feature
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if "parent" in parameters:
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kwvalues["parent"] = parent
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if self.params_as_list:
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return self.function(values, **kwvalues)
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return self.function(*values, **kwvalues)
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except Exception as ex:
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tb = traceback.format_exception(None, ex, ex.__traceback__)
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formatted_traceback = ''.join(tb)
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formatted_traceback = "".join(tb)
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formatted_exception = f"{ex}:<pre>{formatted_traceback}</pre>"
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parent.setEvalErrorString(formatted_exception)
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return None
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@ -99,53 +111,42 @@ def register_function(function, arg_count, group, usesgeometry=False,
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def handlesNull(self):
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return self.handles_null
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helptemplate = string.Template("""<h3>$name function</h3><br>$doc""")
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name = kwargs.get('name', function.__name__)
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helptext = kwargs.get('helpText') or function.__doc__ or ''
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helptemplate = string.Template("<h3>$name function</h3><br>$doc")
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name = kwargs.get("name", function.__name__)
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helptext = kwargs.get("helpText") or function.__doc__ or ""
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helptext = helptext.strip()
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expandargs = False
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if arg_count == "auto":
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# Work out the number of args we need.
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# Number of function args - 2. The last two args are always feature, parent.
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args = inspect.getfullargspec(function).args
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number = len(args)
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arg_count = number - 2
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if args[-1] == 'context':
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arg_count -= 1
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expandargs = True
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register = kwargs.get('register', True)
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register = kwargs.get("register", True)
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if register and QgsExpression.isFunctionName(name):
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if not QgsExpression.unregisterFunction(name):
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msgtitle = QCoreApplication.translate("UserExpressions", "User expressions")
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msg = QCoreApplication.translate("UserExpressions",
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"The user expression {0} already exists and could not be unregistered.").format(
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name)
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msg = QCoreApplication.translate(
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"UserExpressions", "The user expression {0} already exists and could not be unregistered."
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).format(name)
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QgsMessageLog.logMessage(msg + "\n", msgtitle, Qgis.Warning)
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return None
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function.__name__ = name
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helptext = helptemplate.safe_substitute(name=name, doc=helptext)
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f = QgsPyExpressionFunction(function, name, arg_count, group, helptext, usesgeometry, referenced_columns,
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expandargs, handlesnull)
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# This doesn't really make any sense here but does when used from a decorator context
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# so it can stay.
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# Legacy: if args was not 'auto', parameters were passed as a list
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params_as_list = kwargs.get("params_as_list", kwargs.get("args", "auto") != "auto")
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f = QgsPyExpressionFunction(
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function, name, group, helptext, usesgeometry, referenced_columns, handlesnull, params_as_list
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)
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if register:
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QgsExpression.registerFunction(f)
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return f
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def qgsfunction(args='auto', group='custom', **kwargs):
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def qgsfunction(args="auto", group="custom", **kwargs):
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r"""
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Decorator function used to define a user expression function.
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:param args: Number of parameters, set to 'auto' to accept a variable length of parameters.
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:param args: DEPRECATED since QGIS 3.32. Use the "params_as_list" keyword argument instead if you want to pass parameters as a list.
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:param group: The expression group to which this expression should be added.
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:param \**kwargs:
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See below
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:Keyword Arguments:
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* *referenced_columns* (``list``) --
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An array of field names on which this expression works. Can be set to ``[QgsFeatureRequest.ALL_ATTRIBUTES]``. By default empty.
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@ -153,24 +154,36 @@ def qgsfunction(args='auto', group='custom', **kwargs):
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Defines if this expression requires the geometry. By default False.
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* *handlesnull* (``bool``) --
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Defines if this expression has custom handling for NULL values. If False, the result will always be NULL as soon as any parameter is NULL. False by default.
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* *params_as_list* (``bool``) \since QGIS 3.32 --
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Defines if the parameters are passed to the function as a list, or if they are expanded. Default to False.
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Example:
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@qgsfunction(2, 'test'):
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def add(values, feature, parent):
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pass
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Examples:
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Will create and register a function in QgsExpression called 'add' in the
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'test' group that takes two arguments.
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@qgsfunction(group="custom")
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def myfunc(values, feature, parent):
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return values + [feature.id()]
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or not using feature and parent:
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This register a function called "myfunc" in the "custom" group. It can then be called with any number of parameters
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which will be passed as a list to the function. From the function, it is possible to access the feature and the parent
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Example:
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@qgsfunction(2, 'test'):
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def add(values, *args):
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pass
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>>> myfunc("a", "b", "c")
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["a", "b", "c", 1]
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@qgsfunction(group="custom")
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def myfunc2(val1, val2, context):
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return val1 + val2
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This register a function called "myfunc2" in the "custom" group. It expects exactly two parameters, val1 and val2
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From the function, it is possible to access the feature and the parent
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>>> myfunc2(40, 2)
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42
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"""
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kwargs["args"] = args
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def wrapper(func):
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return register_function(func, args, group, **kwargs)
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return register_function(func, group, **kwargs)
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return wrapper
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